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291 results on '"Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS"'

1. Gloss evaluation and prediction of achromatic low-gloss textured surfaces from the automotive industry

Author

S Baron, Caterina Passaro, Olivier Eterradossi, David Delafosse, J.S. Bidoret, School of Agriculture, Food Science and Veterinary Medicine, Pôle RIME - Recherche sur les Interactions des Matériaux avec leur Environnement (RIME), Centre des Matériaux des Mines d'Alès (C2MA), IMT - MINES ALES (IMT - MINES ALES), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-IMT - MINES ALES (IMT - MINES ALES), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Chambre d'agriculture du Loiret, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), and Centre Science des Matériaux et des Structures (SMS-ENSMSE)

Subjects
business.industry, General Chemical Engineering, Automotive industry, Human Factors and Ergonomics, 02 engineering and technology, General Chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Gloss (optics), [SPI.MAT]Engineering Sciences [physics]/Materials, 0104 chemical sciences, law.invention, Optics, Achromatic lens, law, Specular reflection, 0210 nano-technology, business, Reflectometry, ComputingMilieux_MISCELLANEOUS, Mathematics
Abstract

In this article, we investigate the benefit of including texture information in models of gloss perception of low-gloss textured achromatic plastic surfaces from the automotive industry. 4 models are compared: two gloss prediction models including texture information, one using data from reflectometry (M1) and one using data from goniophotometry (M2), and two models using data from reflectometry (M3) or goniophotometry (M4) alone. Both texture-corrected models (M1-M2) outclass the uncorrected intensity-based models, mainly because they are made texture invariant. Although the texture-corrected reflectometer-based prediction (M1) correlates rather well with sensory data, a more consistent fit is obtained by mixing textural to goniophotometric data (M2). This can be explained by the fact that contrast gloss is better than multiangle specular gloss at reflecting the observer's gloss evaluation strategy. © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015

Published
2015

2. Study of the influence of roughness on the gonioapparency of anodized titanium

Author

Quentin Cridling, Jamon Damien, Charrière Renée, Diamanti Maria Vittoria, Delafosse David, Pedeferri Maria Pia, David Delafosse, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Hubert Curien [Saint Etienne] (LHC), and Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Anodizing, chemistry.chemical_element, Computer Science Applications1707 Computer Vision and Pattern Recognition, 02 engineering and technology, Surface finish, 021001 nanoscience & nanotechnology, 01 natural sciences, Computer Graphics and Computer-Aided Design, Human-Computer Interaction, Software, Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, [SPI.MAT]Engineering Sciences [physics]/Materials, 010309 optics, chemistry, [INFO.INFO-TI]Computer Science [cs]/Image Processing [eess.IV], Atomic and Molecular Physics, 0103 physical sciences, Composite material, and Optics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Titanium
Abstract

International audience

Published
2017

3. Hydrogenation method based on electrodeposited layers controlling the hydrogen desorption rate

Author

V. Gaspard, D. Delafosse, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Hydrogen, 020209 energy, NICKEL, Energy Engineering and Power Technology, chemistry.chemical_element, Copper coating, 02 engineering and technology, Ferritic alloys, SUSCEPTIBILITY, Hydrogen desorption, [SPI.MAT]Engineering Sciences [physics]/Materials, DEFORMATION, ENVIRONMENT EMBRITTLEMENT, DISSOLVED HYDROGEN, 0202 electrical engineering, electronic engineering, information engineering, TENSILE PROPERTIES, Nickel coating, Electroplating, ComputingMilieux_MISCELLANEOUS, Renewable Energy, Sustainability and the Environment, Metallurgy, MECHANICAL-PROPERTIES, 021001 nanoscience & nanotechnology, Condensed Matter Physics, STAINLESS-STEEL, Copper, Nickel, ROOM-TEMPERATURE, Fuel Technology, chemistry, HIGH-PURITY IRON, Hydrogen fuel, Deformation (engineering), 0210 nano-technology, Gaseous hydrogenation, Hydrogen embrittlement
Abstract

International audience; An innovative hydrogenation method to investigate the hydrogen embrittlement of metals and alloys is hereby presented. The benefits of electroplating samples with copper and nickel prior to gaseous hydrogenation at mid-range temperatures are quantified. It is showed that these electrodeposited layers allow to control the hydrogen desorption rate occurring after hydrogenation, during the cooling of the hydrogenated specimen. The present study demonstrates the capability of the method to control the introduced total hydrogen concentration within a margin of 0.2 wt.ppm. The applicability of the described method to further investigations into hydrogen concentrations effects on hydrogen embrittlement of ferritic alloys by the means of mechanical tests is evaluated. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Published
2014

4. Substrate Depletion Analysis and Modeling of the High Temperature Oxidation of Binary Alloys

Author

Nicolas Moulin, Patrick Ganster, Krzysztof Wolski, Etienne Marrier, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Substrate depletion, Diffusion, Alloy, Kinetics, Oxide, Thermodynamics, 02 engineering and technology, Substrate (electronics), engineering.material, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Inorganic Chemistry, [SPI]Engineering Sciences [physics], chemistry.chemical_compound, Flux (metallurgy), 0103 physical sciences, Materials Chemistry, SEGREGATION, KINETICS, Oxidation modeling, Variable interdiffusion coefficient, 010302 applied physics, Metallurgy, technology, industry, and agriculture, Metals and Alloys, PROFILES, Binary alloys, equipment and supplies, 021001 nanoscience & nanotechnology, DIFFUSION, chemistry, Inflection point, engineering, METALS, 0210 nano-technology, Layer (electronics)
Abstract

To predict concentration changes in binary alloy due to preferential oxidation during high temperature oxidation, a model based on the flux balance of the oxidized element at the moving oxide/alloy interface has been developed. These changes are driven by the alloy oxidation rate k c . The model is numerically solved considering different initial alloy concentration profiles and a possible diffusion enhancement effect close to the alloy surface. After validating the model by comparison with Wagner’s analytical solution for Ni30wt%–Pt alloy oxidised at 850 °C, we show that the effects of an initial alloy depletion due to the presence of a passive oxide layer are cancelled after very short oxidation times. We also show that a diffusion acceleration due to work-hardening in the vicinity of the alloy surface induces an inflexion point in the depletion profile.

Published
2013

5. Development and characterization of titanium-based bulk metallic glasses

Author

Benedikt Bochtler, Alexander Kuball, Oliver Gross, Ralf Busch, Lucas Ruschel, Mohammad Zamanzade, Bastian Adam, Saarland University [Saarbrücken], Laboratoire Georges Friedel (LGF-ENSMSE), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Centre Science des Matériaux et des Structures (SMS-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Département Mécanique physique et interfaces (MPI-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Materials science, Alloy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 010402 general chemistry, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Materials Chemistry, Composite material, Amorphous metal, Structural material, Mechanical Engineering, Metals and Alloys, Biomaterial, 021001 nanoscience & nanotechnology, Casting, 0104 chemical sciences, Characterization (materials science), Amorphous solid, chemistry, Mechanics of Materials, engineering, 0210 nano-technology, Titanium
Abstract

International audience; The amorphous structure of bulk metallic glasses results in outstanding properties, which are able to outshine the properties of common metallic biomaterials. In particular, Ti-based bulk metallic glasses are interesting candidates for the use as biomaterial or as structural material in lightweight applications. However, the usage of known Ti-based bulk metallic glasses with casting thicknesses of several millimeters is strongly limited due to the large content of rare, expensive and harmful elements. In this work, we design Ni-free Ti-based bulk metallic glasses with a low Cu-content, being suitable for the application as biomaterial. On the basis of the binary Ti-Ni system, novel glass forming alloys are developed by the addition of sulfur. In order to increase the glass forming ability and to reduce the Ni-content, Ti was substituted with Zr and Ni with Cu. Finally, it is possible to produce synchrotron X-ray amorphous samples with a diameter of 3 mm for the Ni-free alloy Ti40Zr35Cu17S8. Furthermore, it is shown that industrial grade raw materials can be used for the synthesis of amorphous samples of this alloy without diminishing the glass forming ability or the mechanical properties. Characterization by mechanical and electrochemical tests proves the superiority of the novel alloys over commercial amorphous and crystalline alloys. All in all, a new class of Ni-free Ti-based bulk metallic glasses with unprecedented properties is developed, being highly attractive for a widespread use.

Published
2023
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6. A simple Eulerian thermomechanical modeling of friction stir welding

Author

Dominique Deloison, Bruno de Meester de Betzenbroeck, Aude Simar, Dimitri Jacquin, F. Montheillet, Christophe Desrayaud, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Centre SMS - ENSMSE - Centre Sciences des Matériaux et des Structures, Centre National de la Recherche Scientifique (CNRS), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Université Catholique de Louvain = Catholic University of Louvain (UCL), EADS Innovation Works [Suresnes] (EADS IW), EADS - European Aeronautic Defense and Space, Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Ecole Nationale Supérieure des Mines, Centre SMS - UMR CNRS 5146, IW12, Suresnes, France, 158 cours Fauriel, 42023 Saint Etienne Cedex 2, Université Catholique de Louvain, iMMC, Louvain-la-Neuve, Belgium, EADS, UCL - EPL/MAPR - Département des sciences des matériaux et des procédés, and UCL - SST/IMMC/MEED - Mechatronic, Electrical Energy, and Dynamics Systems

Subjects
0209 industrial biotechnology, Materials science, Friction stir welding, Simple thermomechanical model, Field (physics), Mechanical engineering, 02 engineering and technology, Welding, Industrial and Manufacturing Engineering, [SPI.MAT]Engineering Sciences [physics]/Materials, Physics::Geophysics, law.invention, Process model, 020901 industrial engineering & automation, law, Thermal, Steady state, Metals and Alloys, Fluid mechanics, Strain rate, 021001 nanoscience & nanotechnology, Thermal conduction, Computer Science Applications, Modeling and Simulation, Ceramics and Composites, 0210 nano-technology
Abstract

International audience; A simple three-dimensional thermomechanical model for friction stir welding (FSW) is presented. It is developed from the model proposed by Heurtier et al. (2006) based on a combination of fluid mechanics numerical and analytical velocity fields. Those velocity fields are introduced in a steady state thermal calculation to compute the temperature field during welding. They allow partial sliding between the shoulder and the workpiece, the amount of which is provided as an additional result of the model. The thermal calculation accounts for conduction and convection effects by means of the particular derivative. The complete thermomechanical history of the material during the process can then be accessed by temperature and strain rate contours. The numerical results are compared with a set of experimental test cases carried out on an instrumented laboratory device. The choices for modeling assumptions, especially tribological aspects, are discussed according to agreements or deviations observed between experimental and numerical results. The amount of sliding appears to be significantly influenced by the welding conditions (welding and tool rotational velocities), and physical interpretations are proposed for its evolution.

Published
2011

7. A new type of 〈0 0 1〉 junction observed in a (B2) Fe–Al–Ni–B alloy by TEM in situ straining

Author

François Louchet, Brigitte Décamps, A. Fraczkiewicz, O. Calonne, David Colas, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Département Rhéologie, Mécanismes, Microstructures et Matériaux Modèles (R3M), EDGe, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Région Rhône-Alpes 'Thématiques prioritaires' program, under the contract No. 00 81 51 41., Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FeAl, Materials science, Intermetallics, Alloy, Intermetallic, Dislocations, Mechanical properties, 02 engineering and technology, engineering.material, Edge (geometry), 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Materials Chemistry, 010302 applied physics, Condensed matter physics, Mechanical Engineering, Metals and Alloys, FEAL, 021001 nanoscience & nanotechnology, Core (optical fiber), Crystallography, Mechanics of Materials, Transmission electron microscopy, TEM, engineering, Dislocation, 0210 nano-technology, Single crystal
Abstract

International audience; Single crystal foils of an FeAl alloy containing Ni and B are strained at elevated temperatures in an in situ dedicated transmission electron microscope (TEM). The observed characteristic "fork-shaped" dislocation configurations are shown to be a kind of "0 0 1 junction". This junction comes from a reaction between two 1 1 1 superdislocations gliding on different {1 1 2} planes; it results in the presence of a long and sessile edge 0 0 1 dislocation along the intersection of the glide planes. Several hypothetical core structures of such a junction are proposed and their possible effects on macroscopic mechanical properties of the alloy are discussed.

Published
2010

8. Microtexture tracking in hot-deformed polycrystalline aluminium: Comparison with simulations

Author

Julian H. Driver, David Piot, Romain Quey, Centre Science des Matériaux et des Structures (SMS-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE), MPM-ENSMSE - Département Microstrucutres et Propriétés Mécaniques, Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), École des Mines de Saint-Étienne, Centre SMS, Laboratoire PECM, CNRS UMR 5146, 158 cours Fauriel, 42023 Saint-Étienne, CEDEX 2, and France

Subjects
Materials science, Polymers and Plastics, chemistry.chemical_element, Mineralogy, Geometry, 02 engineering and technology, Rotation, 01 natural sciences, Modelling, [SPI.MAT]Engineering Sciences [physics]/Materials, Aluminium, Orientation (geometry), Electron backscattering diffraction (EBSD), 0103 physical sciences, Texture (crystalline), Plastic deformation, Microstructure, 010302 applied physics, Metals and Alloys, Aluminium alloys, 021001 nanoscience & nanotechnology, Compression (physics), Electronic, Optical and Magnetic Materials, chemistry, Electron diffraction, Ceramics and Composites, Crystallite, 0210 nano-technology
Abstract

International audience; The average rotations of 157 individual grains measured in an Al-0.1%Mn polycrystal deformed in hot plane-strain compression to a strain of 1.2 have been compared to the predictions from several crystal plasticity models. The Taylor model successfully predicts the distributions of the rotation angles, but overestimates the rate of evolution of the rotation axes, which explains the overestimation of the final texture. The model also provides a first-order agreement for the rotation axes and the final components of the individual grains. The discrepancies are related to the influence of grain interaction. The main mechanisms of texture development at the level of the individual grains are identified through an analysis of their orientation trajectories. The introduction of local grain interactions, which produce a rotation variability at constant orientation, is shown to weaken texture development.

Published
2010

9. Alumina based ceramics for high-voltage insulation

Author

D. Juvé, Hans-Joachim Fitting, Matthieu Touzin, Dominique Goeuriot, Christelle Guerret-Piecourt, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Physics Department, University of Rostock, CNRS : UMR5513 - Ecole Centrale de Lyon - Ecole Nationale d'Ingénieurs de Saint Etienne, and École Nationale Supérieure des Mines - Saint-Étienne - SMS

Subjects
Materials science, Sintering, Insulator (electricity), 02 engineering and technology, Charge trapping SPACE-CHARGE, FLASHOVER, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, DESIGN, 0103 physical sciences, Materials Chemistry, Forensic engineering, Ceramic, Composite material, Al(2)O(3), Grain boundary strengthening, 010302 applied physics, Dielectric strength, Insulators, 021001 nanoscience & nanotechnology, TRANSPORT, Grain size, CRYSTALS, Grain boundaries, visual_art, Ceramics and Composites, visual_art.visual_art_medium, Grain boundary, Crystallite, MICROSTRUCTURE, 0210 nano-technology, SYSTEM
Abstract

International audience; Dielectric breakdown constitutes an important limitation in the use of insulating materials under high-voltage since it can lead to the local fusion and sublimation of the insulator. The role of electrical charge transport and trapping in alumina ceramics on their resistance to this catastrophic phenomenon is studied in this work. In polycrystalline materials, the interfaces between the various phases play a main role because they constitute potential sites for the trapping of electrical charges. The density and the nature of these interfaces can be controlled by the way of the microstructure parameters. So, the aim of the present paper is to highlight the influence of average grain size and intergranular phase crystallization rate on the ability of polycrystalline alumina materials to resist to dielectric breakdown. Thus, it is shown that the control of the process conditions (sintering aids content, powder grain size and thermal cycle) makes it possible to change not only the density (by the average grain size) but also the nature (by the crystallization or not of anorthite) of the grain boundaries. On one hand, at room temperature a high density of interfaces, due to low grain size and highly crystallized intergranular phase, leads to a high dielectric strength. On the other hand, at higher temperature (250 degrees C), the presence of vitreous intergranular phase makes it possible to delay breakdown. That behaviour is explained thanks to charge transport and trapping characterizations. (C) 2009 Elsevier Ltd. All fights reserved.

Published
2010

10. Microtexture tracking in hot-deformed polycrystalline aluminium: Experimental results

Author

Romain Quey, David Piot, Julian H. Driver, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, and Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE)

Subjects
Materials science, Polymers and Plastics, Mineralogy, chemistry.chemical_element, Geometry, 02 engineering and technology, Rotation, Modelling, [SPI.MAT]Engineering Sciences [physics]/Materials, 0203 mechanical engineering, Aluminium, Lattice (order), Electron backscattering diffraction (EBSD), Plastic deformation, Microstructure, Metals and Alloys, Aluminium alloys, 021001 nanoscience & nanotechnology, Electronic, Optical and Magnetic Materials, 020303 mechanical engineering & transports, Electron diffraction, chemistry, Ceramics and Composites, Crystallite, Deformation (engineering), 0210 nano-technology, Electron backscatter diffraction
Abstract

A split sample of Al–0.1%Mn has been deformed by a series of compression tests in a channel-die at 400 °C to a final strain of 1.6. The orientations of 176 grains in a 4 × 4 mm 2 internal surface were followed by high-resolution electron backscatter diffraction at four different strains to compare with crystal plasticity models. Typically 3000 orientations per grain were used to quantify the average lattice rotations of each grain together with their orientation spreads (termed microtexture tracking). The average orientations tend towards the standard β -fibre plane-strain compression texture components, albeit with some variations. The in-grain orientation spreads develop strongly at first, then tend to saturate at high strains. Finally, the influence of grain environment on lattice rotation is examined by means of the rotation “variability at constant orientation”. On average and at the beginning of the deformation, two grains of the same initial orientation, but different neighbours, would rotate by angles that vary by 25% and axes separated by 37°; their orientations at e = 1.2 would vary by 12°.

Published
2010

11. Constituent Particle Break-Up During Hot Rolling of AA 5182

Author

Helmut Klocker, Annabelle Bigot, Eric Maire, Christophe Ducottet, Estelle Parra-Denis, Nicolas Moulin, Elodie Boller, Dominique Jeulin, Cécile Barat, EMSE, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Centre de Morphologie Mathématique (CMM), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire Hubert Curien [Saint Etienne] (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Alcan Centre de Recherches de Voreppe, Alcan, European Synchrotron Radiation Facility (ESRF), Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), and The present work was supported by Région Rhône-Alpes. (Projet prioritaire Matériaux. Rupture de particules intermétalliques pendant le laminage à chaud d'alliages d'aluminum).

Subjects
Work (thermodynamics), Materials science, Finite elements, Alloy, Population, chemistry.chemical_element, 02 engineering and technology, engineering.material, Aluminum matrix, Plane strain compression, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Aluminium, Particle morphologies, 0103 physical sciences, Elasto-viscoplastic, General Materials Science, Failure criteria, Composite material, As-cast, education, Stress concentration, 010302 applied physics, education.field_of_study, Hot-rolled, Particles break-up, Closure panels, Statistical approach, Failure behaviors, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Finite element method, Morphological parameters, FE model, Micro-mechanical, chemistry, Break-up, Inter-metallic particle, Statistical analysis, Casting (metalworking), Nonconvex, engineering, Rolled sheets, Particle, Body panels, 0210 nano-technology, X-ray tomography, Alloy sheets
Abstract

Article first published online: 17 DEC 2009; International audience; Aluminum sheet is currently used for body panels on a number of mass-produced vehicles, in particular for closure panels. AA5xxx alloys always contain coarse inter-metallic particles (Al x(Fe,Mn) ySi, Mg 2Si) after casting. In the present work inter-metallic particle break-up during hot reversible rolling of AA5182 alloy sheets has been analyzed. The sizes and shapes of inter-metallic particles in as-cast and industrially hot rolled AA5182 alloys sheets were characterized by 3D X-ray tomography observations. The relation between particle break-up and particle morphology was then analyzed statistically and by a micromechanical finite element (FE)-based model. The essential outcomes of the statistical approach may be summarized as follows. The inter-metallic particle population may be described by five morphological parameters. Secondly the comparison of the particle morphology in as cast and industrially rolled sheets leads to the definition of five classes. The evolution of each particle class as function of the rolling strain is provided. The statistical analysis shows which particles break-up. The stresses and strains in inter-metallic particles, embedded in an elasto-viscoplastic aluminum matrix submitted to plane strain compression, were analyzed by an FE model. A new failure criterion was proposed. The essential outcomes of the mechanical approach are as follows: a precise description of stress concentration mechanisms in nonconvex particles, a close description of the parameters controlling particle break-up, and finally a simplified classification of the failure behavior.

Published
2010

12. Relationships between microstructure, mechanical and dielectric properties of different alumina materials

Author

Daniel Treheux, Dominique Goeuriot, N. Mesrati, L. Haddour, Laboratoire Science et Génie des matériaux, Ecole Nationale Polytechnique [Alger] (ENP), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Wear resistance, Toughness, Materials science, Dielectric strength, 02 engineering and technology, Dielectric, Tribology, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Grain size, Reinforcement, [SPI.MAT]Engineering Sciences [physics]/Materials, Breakdown, Phase (matter), Al2O3, Microstructure final, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, Composite material, Toughness and toughening, 0210 nano-technology, Porosity
Abstract

International audience; Different alumina materials were elaborated in order to vary microstructural parameters (grain size, densification, porosity, inter-granular phase). These ceramic materials were then characterized from the mechanical point of view (hardness, toughness, friction and wear) and dielectric breakdown. The comparison of these various results shows that, for all these properties, the grain size and also, the nature of the secondary phases and the microstructural parameters were the most significant. Moreover, from the tribological point of view, the dielectric characteristic of materials (breakdown strength) has a fundamental role in the creation of agglomerated wear debris (“third body”) and its properties: a finely agglomerated third body will be obtained for high breakdown strength. Such third body will be able to protect the substrate and thus to reduce later wear. In the same logic a correspondence between breakdown strength and toughness was established, thus confirming the existence of mechanical–electrical correlation for non-conductive materials.

Published
2009

13. EBSD analysis of polysilicon films formed by aluminium induced crystallization of amorphous silicon

Author

Ivan Gordon, P.C. Montgomery, Claire Maurice, Guy Beaucarne, A. Slaoui, Jef Poortmans, A. Focsa, Ö. Tüzün, J. M Auger, Institut d'Electronique du Solide et des Systèmes (InESS), Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), IMEC (IMEC), and Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven)

Subjects
Amorphous silicon, Materials science, chemistry.chemical_element, 02 engineering and technology, engineering.material, 7. Clean energy, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, Aluminium, 0103 physical sciences, Materials Chemistry, Thin film, Composite material, 010302 applied physics, Metals and Alloys, Surfaces and Interfaces, 021001 nanoscience & nanotechnology, Grain size, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Crystallography, Polycrystalline silicon, chemistry, engineering, Aluminium oxide, 0210 nano-technology, Layer (electronics), Electron backscatter diffraction
Abstract

Proceedings on Advanced Materials and Concepts for Photovoltaics EMRS 2007 Conference, Strasbourg, France; International audience; Among the methods for enlarging the grain size of polycrystalline silicon (poly-Si) thin films, aluminium induced crystallization (AIC) of amorphous silicon is considered to be a very promising approach. In the AIC process, a thin a-Si layer on top of an aluminium layer crystallizes at temperatures well below the eutectic temperature of the Al/Si system (Teu = 577 °C). By means of electron backscattering diffraction (EBSD), we have mainly studied the effect of the aluminium layer quality varying the deposition system on the grain size, the defects and the preferential crystallographic orientation. We have found a strong correlation between the mean grain size and the size distribution with the Al deposition system and the surface quality. Furthermore, we show for the first time that more than 50% of the surface of the AIC films grown on alumina substrates are (103) preferentially oriented, instead of the commonly observed (100) preferential orientation. This may have important consequences for epitaxial thickening of the AIC layer into polysilicon absorber layers for solar cells.

Published
2008

14. Evolution of Microstructure and Texture during Hot Torsion of Ferritic Stainless Steels Stabilized by Nb and Ti

Author

F. Montheillet, Tarcísio Reis de Oliveira, Centro de Pesquisas, ArcelorMittal Inox Brasil, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Materials science, recrystallization, microstructure, 02 engineering and technology, Flow stress, 01 natural sciences, hot deformation, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Materials Chemistry, Physical and Theoretical Chemistry, Composite material, 010302 applied physics, AXIAL STRESSES, Metals and Alloys, Torsion (mechanics), Recrystallization (metallurgy), 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, stabilization, ferritic stainless steel, Volume fraction, Dynamic recrystallization, Hardening (metallurgy), 0210 nano-technology, texture, Electron backscatter diffraction
Abstract

International audience; The study was carried out to understand the mechanisms occurring during dynamic recrystallization of hot deformed 11 % chromium stabilized ferritic stainless steels and to compare the behaviour induced by various types of stabilization. The experimental temperatures ranged from 800 to 1150 °C and strain rates from 10-2 to 15 s-1. The development of the textures and microstructures was analysed using EBSD maps. It was observed that continuous dynamic recrystallization occurs in all materials starting at the onset of straining. Niobium has a more pronounced influence on hardening than titanium during hot deformation. The D2 component was found as the major texture component at the steady state for the torsion tests conducted along the negative shear direction. It was likely to be formed by the combination of straining and growth of the grains exhibiting both low stored energy and low rotation rate of the crystallographic axes. The texture evolution was the main reason for the flow stress behavior during the hot torsion tests. A complementary study was carried out to understand the texture formation occurring during the direct (negative shear direction) and reversed (positive shear direction) hot torsion. After reversion of the shear direction, i.e. during positive shear, the above major texture component is gradually changed into the D1 component. Using the method of Continuum Mechanics of Textured Polycrystals, the stress evolution is explained by the volume fraction changes of each component at various strains, associated with their respective Taylor factors. This simplified approach leads to a good agreement with experimental results.

Published
2008

15. High temperature reactivity of two chromium-containing alloys in impure helium

Author

Michèle Pijolat, Krzysztof Wolski, Fabien Rouillard, Céline Cabet, Jerome Chapovaloff, Gouenou Girardin, Damien Kaczorowski, Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Corrosion Chemistry Dept, AREVA NP - Centre Technique (FRANCE), FDEEM Metall Alloy Grp, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Procédés et évolution des systèmes avec solides (ProcESS-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN

Subjects
Nuclear and High Energy Physics, 020209 energy, Alloy, chemistry.chemical_element, 02 engineering and technology, engineering.material, 7. Clean energy, [SPI.MAT]Engineering Sciences [physics]/Materials, Corrosion, chemistry.chemical_compound, Chromium, Operating temperature, 0202 electrical engineering, electronic engineering, information engineering, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, General Materials Science, GAS-COOLED REACTORS, Chemistry, Metallurgy, IMPURITIES, CORROSION, [CHIM.MATE]Chemical Sciences/Material chemistry, Partial pressure, 021001 nanoscience & nanotechnology, Chromia, PRIMARY CIRCUIT HELIUM, Nuclear Energy and Engineering, 13. Climate action, INCONEL-617, engineering, 0210 nano-technology, Carbon, Nuclear chemistry, Carbon monoxide
Abstract

International audience; Chromium-rich nickel base alloys 617 and 230 are promising candidate materials for very high temperature gas-cooled reactors (VHTR) but they must resist corrosion in the impure primary cooling helium over very long times. The impurities of the hot helium can promote the development of chromium-rich surface oxides that appear to protect the alloys against intensive corrosion processes. However above a critical temperature (typically in the range 1173-1273 K), chromium oxide is reduced by carbon from the alloy and the surface layer is not stable anymore. Depending oil the gas composition, the unprotected material rapidly either gains or loses carbon with a dramatic impact on its mechanical properties. The deleterious reaction of chromia and carbon thus fixes all ultimate reactor operating temperature. Critical temperature measurements are presented for alloys 617 and 230 and the influence of carbon monoxide partial pressure in helium is discussed.

Published
2008

16. Boundary Mobilities during Recovery and Recrystallization of Binary Al - Mn Alloys

Author

Alban Guillotin, Julian H. Driver, Fabrice Barou, Jean-Marie Feppon, Claire Maurice, Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Alcan Centre de Recherches de Voreppe, and Alcan

Subjects
Materials science, Sub-Boundary Mobilities, Annealing (metallurgy), Thermodynamics, Binary number, 02 engineering and technology, Activation energy, Grain Boundary Mobility, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Recovery, Solvent drag, 0103 physical sciences, SEM/EBSD, Grain boundary diffusion coefficient, Solute Drag, General Materials Science, 010302 applied physics, Aluminium-Magnesium Alloy, Mechanical Engineering, Metallurgy, Recrystallization (metallurgy), Recrystallization, Activation Energy, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Mechanics of Materials, Grain boundary, 0210 nano-technology
Abstract

Publication suite au congrès : Proc. Rex & GG 3 (Corée du Sud 2006); International audience; This paper described new characterization methods and data to quantify the influence of solute atoms on grain boundary and sub-grain boundary mobilities in Al-Mn alloys with a view to their integration into recovery and recrystallization modelling. Detailed SEM measurements of grain boundary mobilities during recrystallization have been made by in-situ annealing experiments on cold deformed Al – 0.1 and 0.3wt.% Mn binary alloys. Stored energies are estimated from the sub-grain sizes and misorientations and the boundary velocities directly measured in the temperature range 200-450°C. It is shown that in many cases good agreement with the Cahn, Lücke, Stüwe model for solute drag is obtained, e.g. the activation energies are intermediate between those of boundary and volume solute diffusion. Some particular cases of rapid growth occur in Al-0.1%Mn indicating boundary breakaway from solute clouds. A complementary study of sub-grain boundary mobilities has started on the same alloys; in this case the average mobilities are estimated from FEG-SEM growth data for the average sub-grain size for temperatures in the range 150-300°C. The results are compared with some previous data on Al- Si and show similar rates.

Published
2007

17. Microstructural refinement of an Fe–C alloy within the ferritic range via two different strain paths

Author

Frank Montheillet, S.M. Lim, M. El Wahabi, Christophe Desrayaud, Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Departamento de Ciencia de los Materiales e Ingenieria Metalúrgica (ETSEIB-Universidad Politécnica de Cataluña), and Universitat Politècnica de Catalunya [Barcelona] (UPC)

Subjects
Torsion, Materials science, Stress path, Alloy, 02 engineering and technology, engineering.material, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Severe plastic deformation (SPD), 0103 physical sciences, Microscopy, General Materials Science, High angle, Ferritic steel, 010302 applied physics, Mechanical Engineering, Metallurgy, Torsion (mechanics), 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Multiaxial compression (MAC), Mechanics of Materials, engineering, Crystallite, Severe plastic deformation, 0210 nano-technology, Grain refinement
Abstract

International audience; One of the most popular approaches to ultrafine grain formation within bulk samples is severe plastic deformation (SPD). In this paper, grain refinement by two SPD techniques involving different strain paths, namely multiaxial compression (MAC) and torsion, has been investigated. A coarse-grained, high-purity iron-carbon alloy was deformed within the ferritic domain under cold and warm working conditions to large strains (>>1). Subsequent analyses by orientation imaging microscopy revealed that the nature and extent of refinement depend upon the processing route. In MAC, fragmentation occurs mainly by means of a dense, homogeneous network of low angle boundaries (LAB, 2 ≤ θ ≤ 15°) delimiting subgrains, and only a few strain-induced high angle boundaries (HAB, θ ≥ 15°) are observed in localised regions of cold worked samples. In torsion, however, the proportion of HAB is significantly higher (37-54%), giving rise to a fragmented microstructure comprising ultrafine crystallites (1-2 μm).

Published
2007

18. Oxide-Layer Formation and Stability on a Nickel-Base Alloy in Impure Helium at High Temperature

Author

Céline Cabet, Krzysztof Wolski, Fabien Rouillard, M. Pijolat, Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Etude de la Corrosion Non Aqueuse (LECNA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Département de Physico-Chimie (DPC), Département Procédés et évolution des systèmes avec solides (ProcESS-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Département Mécanique physique et interfaces (MPI-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
inorganic chemicals, 020209 energy, Alloy, Oxide, chemistry.chemical_element, 02 engineering and technology, engineering.material, 7. Clean energy, Decarburization, [SPI.MAT]Engineering Sciences [physics]/Materials, Corrosion, Inorganic Chemistry, chemistry.chemical_compound, Chromium, Oxidation, 0202 electrical engineering, electronic engineering, information engineering, Materials Chemistry, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, High-temperature corrosion, Metallurgy, technology, industry, and agriculture, Metals and Alloys, High temperature, equipment and supplies, 021001 nanoscience & nanotechnology, Nickel base alloy, chemistry, 13. Climate action, engineering, 0210 nano-technology, Carbon, Carbon monoxide
Abstract

The corrosion behavior in impure helium of Haynes 230, a nickel base alloy candidate for heat exchangers in Very High Temperature Reactors (VHTR), has been investigated. The study focused on the formation and the subsequent destruction of the surface oxide layer at 900 °C and 980 °C. In-situ gas-phase analysis coupled to post-exposure surface analyses showed that a chromium-rich surface oxide formed on Haynes 230 at 900 °C but was unstable above a critical temperature T A : the chromium-rich oxide reacted with carbon in solution in the alloy to produce chromium and CO(g). The effect of carbon monoxide partial pressure in the gas phase as well as the influence of chromium and carbon activities in the alloy on T A are discussed taking thermodynamics and kinetics aspects into account.

Published
2007

19. Electron beam excitation in thin layered samples

Author

Roushdey Salh, Dominique Goeuriot, Christelle Guerret-Piecourt, Hans-Joachim Fitting, A. von Czarnowski, N. Cornet, Physics Department, University of Rostock, Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Physico-chimie des polymères (PCP), Centre National de la Recherche Scientifique (CNRS)-Université de Pau et des Pays de l'Adour (UPPA), Laboratoire d'Ingénierie et Fonctionnalisation des Surfaces (IFoS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)

Subjects
Multilayer targets, Reflection high-energy electron diffraction, Scanning electron microscope, Energy-dispersive X-ray spectroscopy, Electron energy deposition, Cathodoluminescence, 02 engineering and technology, 7. Clean energy, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Scanning transmission electron microscopy, Energy filtered transmission electron microscopy, Physical and Theoretical Chemistry, Electron beam-induced deposition, Spectroscopy, 010302 applied physics, Radiation, Chemistry, Electron excitation functions, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electron range, Electronic, Optical and Magnetic Materials, Electron tomography, Atomic physics, 0210 nano-technology
Abstract

International audience; Energy transfer distributions dE/dx and respective excitation depth functions Φ of electron beams in heterogeneous layered samples are described by a successive Effective Layer method. This method is based on electron transmission rates through the top multilayer system replaced by an “effective layer” of the following bottom material. Thus energy depositions in heterogeneous layered metal samples (Al, Ag and Au) and dielectric insulating samples SiO2–Al2O3 are given. For the latter ones special energy-range relations R(E0) have been deduced for the common energy regions (1–30) keV of scanning electron microscopy (SEM). Application are given by cathodoluminescence depth profiling and electron beam charging of non-conductive samples.

Published
2007

20. Relationships between dielectric breakdown resistance and charge transport in alumina materials—Effects of the microstructure

Author

D. Juvé, Daniel Treheux, Christelle Guerret-Piecourt, Dominique Goeuriot, H.-J. Fitting, M. Touzin, Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Physics Department, University of Rostock, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, Materials science, Condensed matter physics, Dielectric strength, Interfaces, Insulator (electricity), 02 engineering and technology, Dielectric, Electron, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Grain size, [SPI.MAT]Engineering Sciences [physics]/Materials, Grain boundaries, Dielectric properties, Electric field, Al2O3, 0103 physical sciences, Materials Chemistry, Ceramics and Composites, Forensic engineering, Grain boundary, 0210 nano-technology
Abstract

International audience; Dielectric breakdown is the main cause of insulator degradation. Breakdown strength strongly depends on materials microstructure (grain size, grain boundaries nature,...) [Liebault, J., Vallayer, J., Goeuriot, D., Tréheux D., Thévenot, F., How the trapping of charges can explain the dielectrics breakdown performance of alumina ceramics, J. Eur. Ceram. Soc., 2001, 21, 389–397; Si Ahmed, A., Kansy, J., Zarbout, K., Moya, G., Liebault, J., Goeuriot, D., Microstructural origin of the dielectric breakdown strength in alumina: a study by positron lifetime spectroscopy, J. Eur. Ceram. Soc., 2005, 25, 2813–2816]. The experimental study of these materials behaviour towards charge injection was performed by the scanning electron microscopy mirror effect (SEMME) method. It allows to measure the amount of injected charges finally trapped in the insulator. In order to explain the experimental results, we developed an iterative computer simulation of the self-consistent charge transport in bulk alumina samples during electron beam irradiation, based on a new flight-drift model (FDM). Ballistic and drift electron and hole transport as well as their recombination, trapping and detrapping (due to temperature and electric field) are taken into account. As a main result the time dependent secondary electron emission rate and the spatial distributions of currents, charges, field and potential are obtained. The analysis of these two kinds of results allowed us to identify the effect of the microstructure on the behaviour of the injected charges in the insulator and then to propose some mechanisms depending on the temperature leading to a good dielectric breakdown resistance. Indeed, at room temperature a huge localisation of charges limits further injection into the sample that permits to delay breakdown. On the other hand, when the temperature increases, the efficiency of the charge spreading behaviour is improved, leading to a higher dielectric breakdown strength.

Published
2007

21. Correlation between dislocation organization and slip bands: TEM and AFM investigations in hydrogen-containing nickel and nickel-chromium

Author

David Delafosse, Gouenou Girardin, Xavier Feaugas, C. Huvier, Laboratoire Georges Friedel (LGF-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Département Mécanique physique et interfaces (MPI-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire des Sciences de l'Ingénieur pour l'Environnement - UMR 7356 (LaSIE), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude des Matériaux en Milieux Agressifs (LEMMA), and Université de La Rochelle (ULR)

Subjects
Equiaxed crystals, Materials science, Polymers and Plastics, 02 engineering and technology, Slip (materials science), Slip bands, Flow stress, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Stacking-fault energy, Nickel, INTERNAL HYDROGEN, 0103 physical sciences, STRAIN LOCALIZATION, Composite material, FLOW-STRESS, ComputingMilieux_MISCELLANEOUS, Dislocation patterns, 010302 applied physics, HIGH-PURITY ALUMINUM, ALUMINUM SINGLE-CRYSTALS, Lüders band, Metals and Alloys, AUSTENITIC STAINLESS-STEEL, Strain hardening exponent, 021001 nanoscience & nanotechnology, GRAIN-ORIENTATION DEPENDENCE, CONSTITUTIVE MODEL, Electronic, Optical and Magnetic Materials, Nickel-chromium, Crystallography, CYCLIC DEFORMATION, Ceramics and Composites, Dislocation, Deformation (engineering), 0210 nano-technology, MEAN FREE PATHS, Hydrogen
Abstract

International audience; Various forms of the plastic deformation in single crystals are studied in pure and hydrogen-containing nickel and nickel alloys oriented for single slip [1 3 5] and strained in the stage III regime (shear strain, gamma = 0.8). The heterogeneity of deformation is investigated at two distinct scales: slip bands and dislocation structures, using atomic force microscopy (AFM) and transmission electronic microscopy (TEM). Size and distribution of slip band thicknesses and geometrically necessary boundary (GNB) spacing are comparable. GNB structures both screen the long-range stress fields and decrease the mean free path of mobile dislocations, whereas equiaxed cells only impede dislocation motion through their role as obstacles. Consequently, GNB formation localizes deformation in specific slip bands. Additionally, the observed similarity between GNB spacing and equiaxed cell size suggests a correlation between these microstructural features. The impact of solid solution atoms on the inter-wall spacing is established for chromium and hydrogen. Both decrease the GNB spacing because of a decrease of the cross-slip probability and stacking fault energy, combined to a shielding effect for the later. The effect of GNB spacing on strain hardening is discussed in terms of the length scale associated with GNBs and the effect of solute content. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Published
2015

22. Structural Colors of Nanoporous Anodic Alumina: Overview of Recent Advances and Case Study in Elaboration, Characterization, Photometry and Modelling

Author

Natalia Matsapey, Jenny Faucheu, Renée Charrière, David Delafosse, Manuel Flury, Laboratoire Georges Friedel (LGF-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Mécanique physique et interfaces (MPI-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire Hubert Curien [Saint Etienne] (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Institut Mines-Télécom [Paris] (IMT), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
MORPHOLOGY CONTROL, Materials science, Nanostructure, Fourier modal method, nanostructure, OXIDE FILMS, Biomedical Engineering, Pharmaceutical Science, Medicine (miscellaneous), Physics::Optics, Bioengineering, Nanotechnology, 02 engineering and technology, 01 natural sciences, NANOSTRUCTURES, [SPI.MAT]Engineering Sciences [physics]/Materials, nanoporous anodic alumina, symbols.namesake, TRANSMISSION SPECTRA, ANODIZATION, ORDERED POROUS ALUMINA, Chromatic scale, Specular reflection, ComputingMilieux_MISCELLANEOUS, Anodizing, Nanoporous, 010401 analytical chemistry, CONSTANTS, BRDF, OPTICAL-PROPERTIES, structural color, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Nanopore, Fourier transform, ACID, symbols, GROWTH, 0210 nano-technology, RCWA, Structural coloration, Biotechnology
Abstract

International audience; Anodizing of aluminum generates a nanoporous alumina layer comprising cylindrical nanopores extending essentially perpendicular to the substrate. Visual observation of such nanoporous layers shows a colored specular reflectance consistent with reflectance spectrum measurements. Such structural colors raise interest in particular for producing non-fading colors. However the optical behavior is complex and requires specific characterization setups and modelling approaches. A morphological and optical characterization of nanoporous anodic alumina has been performed and enabled to draw the chromatic paths. Moreover, the optical behavior has been compared to numerical simulations of optical properties using the Fourier Modal Method, thus demonstrating the impact of short-range order and long-range disorder on the formation of structural colors in these partially ordered nanostructures.

Published
2015

23. 3D finite element simulation of the inhibition of normal grain growth by particles

Author

Claire Maurice, G. Couturier, Roger D. Doherty, Roland Fortunier, Département microstructures et mise en forme (MMF), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Department of Materials Science and Engineering (MSE), Drexel University, Département Mécanique et Matériaux (MEM), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Materials science, Polymers and Plastics, Zener pinning, Boundary (topology), 02 engineering and technology, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Vertex model, Grain boundary diffusion coefficient, Grain boundary migration, 010302 applied physics, Condensed matter physics, Metals and Alloys, 021001 nanoscience & nanotechnology, Grain growth, Electronic, Optical and Magnetic Materials, Classical mechanics, Drag, Ceramics and Composites, Grain boundary, Zener diode, 0210 nano-technology, Simulation
Abstract

International audience; An original model to simulate single grain boundary motion and its interaction with particles (Couturier G, Maurice C, Fortunier R. Phil Mag 2003;83:3387) is applied to model curvature driven grain growth. For single phase material, the single grain boundary model closely matches the grain coarsening kinetics of a 3D multi boundary vertex model. In the presence of spherical incoherent particles the growth rate slows down to give a growth exponent of 2.5. When the boundary is anchored there is a significantly higher density, four times higher, of particles on the boundary than the density predicted by the classic Zener analysis, but particles exert, on average, a drag force about half of the maximum value assumed by Zener. As a result the Zener drag is increased by a factor of 2.2. The limiting grain radius is compared with some experimental results.

Published
2005

24. Spectroscopic analysis of 'MgAlON' spinel powders: influence of nitrogen content

Author

Philippe Grosseau, Olivier Morey, Mourad Benabdesselam, Bernard Guilhot, P. Goeuriot, Philibert Iacconi, Département céramiques spéciales (CES), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Poudres et Matériaux Multi-Composants (P2MC-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique de la matière condensée (LPMC), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Electronique des Solides (LPES), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Université de Nice-Sophia Antipolis, Institut Mines-Télécom [Paris] (IMT), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Physico-Chimie des Matériaux Multicomposants (PC2M), Laboratoire de Physique Electronique des Solides, and Laboratoire de Physique Electronique des Solides (LPES EA1174)

Subjects
Materials science, Thermoluminescence, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, Oxygen, Fluorescence, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, 0103 physical sciences, Oxidizing agent, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, General Materials Science, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, Magnesium, Aluminium oxynitride, Spinel, MgAlON, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Nitrogen, MgAl2O4, chemistry, 13. Climate action, engineering, 0210 nano-technology, Solid solution
Abstract

The thermoluminescence (TL) and fluorescence spectra of magnesium aluminium oxynitride “MgAlON” and magnesium aluminate MgAl 2 O 4 spinel powders have been analysed. Two broad peaks at about 100 and 300 °C appear in the TL spectra of MgAl 2 O 4 and seem to be related to electron and hole release from [Al Mg ] and [Mg Al ′] traps, respectively. The intensity of each peak strongly depends on the nature of the annealing atmosphere (neutral, oxidizing or reducing). TL spectral analyses have shown the presence of two intense emissions at 520 and 690 nm attributed to the Mn 2+ and Cr 3+ emitting centers, respectively. A study on MgAl 2 O 4 is used as a reference for MgAlON powders, which can be considered as a solid solution derived from magnesium aluminate. Disturbance in the emission spectrum of Cr 3+ is clearly observed with the nitrogen/oxygen substitution.

Published
2003

25. A mechanical analysis of the plane strain channel-die compression test: friction effects in hot metal testing

Author

C. Chovet, Frank Montheillet, Ch. Desrayaud, Centre Science des Matériaux et des Structures (SMS-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Département microstructures et mise en forme (MMF), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Science et Ingénierie des Matériaux et Procédés (SIMaP), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010302 applied physics, business.product_category, Materials science, Mechanical Engineering, Numerical analysis, 02 engineering and technology, Mechanics, Flow stress, Plasticity, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Compression (physics), 01 natural sciences, Finite element method, Mechanics of Materials, 0103 physical sciences, Calculus, Die (manufacturing), General Materials Science, Deformation (engineering), 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS, Civil and Structural Engineering, Plane stress
Abstract

An analytical model is first proposed for the determination of a friction-corrected flow stress in channel-die compression. A variational approach is then used for estimating the strain and strain-rate heterogeneities as well as the shape changes during deformation for two specimen geometries. The results are compared with finite element calculations. Results obtained from the two methods are in good agreement, except for the outer profiles of the deformed specimens. Finally, the various components of the powers involved in the deformation process are compared.

Published
2002

26. Correlation of Surface Roping with Through-Thickness Microtextures in an AA6xxx Sheet

Author

Julian H. Driver, Claire Maurice, Alban Guillotin, Gilles Guiglionda, Centre Science des Matériaux et des Structures (SMS-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Centre de recherches de Voreppe (ALCAN CRV), Alcan, MPM-ENSMSE, Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Ecole Nationale Supérieure des Mines, MPM, 158 Cours Fauriel, 42023 St Etienne 2, France, Alcan Centre Recherche Voreppe, and F-38341 Voreppe

Subjects
Materials science, Correlation coefficient, EBSD, TEXTURE, 02 engineering and technology, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Surface roughness, Texture (crystalline), AA6111 AUTOMOTIVE SHEET, 010302 applied physics, FERRITIC STAINLESS-STEEL, Metallurgy, Metals and Alloys, ALUMINUM, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Grain size, Wavelength, Mechanics of Materials, visual_art, visual_art.visual_art_medium, Tola, 0210 nano-technology, Sheet metal, Electron backscatter diffraction
Abstract

International audience; Strain-induced surface roughness was quantitatively correlated with microtexture spatial distributions from the surface to the midthickness of a strongly roping AA6016 sheet. The microtexture variations through the sheet were measured by acquiring a series of large area electron backscatter diffraction (EBSD) scans at intervals of about the grain size. The orientations of the different layers were translated into out-of-plane strains using a crystal plasticity model for comparison with the surface roping. The spatial distributions (particularly the characteristic wavelengths) of the microtexture layers were determined by areal auto-correlation functions, and quantitatively compared to the surface appearance by correlation coefficients. The results show that texture banding of Cube/Goss components along the rolling direction is present from the surface to midthickness but with significant variations from one grain layer to another. The wavelength correlation coefficient exhibits a maximum at about 55 mu m, or 2 grain thicknesses, below the surface. It is shown that the spatial distribution of Cube/Goss components of the first three or four surface grain layers plays an important role in strong roping of AA6016 sheets.

Published
2011

27. A method for accurate localisation of EBSD pattern centres

Author

Roland Fortunier, K. Dzieciol, Claire Maurice, Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Ecole Natl Super Mines, Ctr SMS, UMR 5146, CNRS, F-42023 St Etienne 2, France, Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-SMS-UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Ecole Nationale Supérieure des Mines, Centre SMS - UMR CNRS 5146, 158 cours Fauriel, 42023 Saint Etienne Cedex 2, and France

Subjects
Diffraction, Pattern centre, Rotation, Computer science, EBSD, Statistics as Topic, Cross-correlation, 02 engineering and technology, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Optics, Position (vector), 0103 physical sciences, Calibration, Zoom, Instrumentation, 010302 applied physics, Crystallography, Pixel, business.industry, Detector, 021001 nanoscience & nanotechnology, Image Enhancement, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Displacement field, Microscopy, Electron, Scanning, Radiographic Image Interpretation, Computer-Assisted, 0210 nano-technology, business, Algorithm, Algorithms
Abstract

International audience; The moving screen technique for pattern centre localisation is revisited. A cross-correlation based iterative procedure is developed to find both the zoom factor and the zoom centre (which is also the pattern centre) between two EBSD diffraction patterns acquired at two camera positions. The procedure involves two steps: first, a rough estimate of the pattern centre position and zoom factor (the ratio of the two detector distances) is obtained by cross-correlating the entire images. Then, based on this first estimate, cross-correlation of smaller regions of interest (ROIs) gives the displacement field which is interpreted as a zoom factor misfit coupled with a zoom centre position misfit. These misfits are iteratively decreased until the displacement field is reduced to the noise level. The procedure is first applied to simulated patterns and it is shown that the iterative procedure converges very rapidly to the exact solution with an accuracy better than 1/100th of pixel. The potential of this technique for experimental patterns is discussed and recommendations for new EBSD detectors are proposed.

Published
2011

28. Factors affecting the accuracy of high resolution electron backscatter diffraction when using simulated patterns

Author

Angus J. Wilkinson, Thomas Benjamin Britton, A. P. Day, David J. Dingley, Ken Mingard, Roland Fortunier, Graham Meaden, Claire Maurice, Julian H. Driver, Department of Materials, University of Oxford, Department of Materials, University of Oxford [Oxford]-University of Oxford [Oxford], MPM-ENSMSE, Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-MPM-ENSMSE - Département Microstructures et Propriétés Mécaniques, Aunt Daisy Scientific Ltd, Aunt Daisy Scientific Ltd, Lydney, Aunt Daisy Scientific Ltd, Lydney-Aunt Daisy Scientific Ltd, Lydney, BLG Productions, Bristol, BLG Productions Bristol-BLG Productions Bristol, University of Bristol [Bristol], Materials Division [NPL Teddington], National Physical Laboratory [Teddington] (NPL), Department of Materials, Oxford, University of Oxford, Lydney, Gloucester, BLG Productions, Sydenham Road, Bristol, University of Bristol, Tyndall Avenue, Materials Division, National Physical Laboratory, Teddington, Parks Road, UK, Oxford, Ecole Nationale Supérieure des Mines, Saint Etienne, France, and Claremont House

Subjects
Diffraction, Materials science, Microscope, SOURCE POINT, EBSD, 02 engineering and technology, 01 natural sciences, Strain, [SPI.MAT]Engineering Sciences [physics]/Materials, law.invention, Electron diffraction BACK-SCATTER DIFFRACTION, Optics, law, 0103 physical sciences, Calibration, MICROSCOPE, Instrumentation, CALIBRATION, 010302 applied physics, Orientation (computer vision), business.industry, Resolution (electron density), Scanning electron microscope, ELASTIC STRAIN-MEASUREMENT, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Electron backscatter diffraction, Electron diffraction, 13. Climate action, ORIENTATION, 0210 nano-technology, business, Rotation (mathematics)
Abstract

International audience; High resolution EBSD directly compares electron backscattering patterns (EBSPs), generated in a scanning electron microscope, to measure relative strain and rotation to a precision of ∼10−4 in strain and 10−4 rad (0.006°) in rotation. However the measurement of absolute strain and rotation requires reference EBSPs of known strain and orientation (or a far field region of known strain). Recent suggestions of using simulated EBSPs with known strain show much promise. However precise measurement of the experimental geometry (pattern centre) is required. Common uncertainties of 0.5% in pattern centre result in uncertainty of ∼10−3 in strain state. Aberrations in the compact lenses used for EBSP capture can also result in image shifts that correspond to strains/rotations of ±10−3 between experimental and simulated EBSPs. Simulated EBSPs can be generated using dynamical or kinematic models (or a combination of the two). The choice in simulation model has a significant effect on the measured shifts, particularly at zone axis and high structure factor bands, due to large intensity variations, and for simple kinematic simulations can result in the measurement of rogue shifts and thus erroneous strain measurements. Calibrant samples of known strain provide a method of measuring the experimental geometry but imprecise stage movement combined with the high depth of field in the SEM could also result in uncertainties in strain of ∼10−3.

Published
2010

29. Comments on the paper 'Bragg's law diffraction simulations for electron backscatter diffraction analysis' by Josh Kacher, Colin Landon, Brent L. Adams & David Fullwood

Author

Julian H. Driver, A. P. Day, Roland Fortunier, Ken Mingard, Graham Meaden, Claire Maurice, MPM-ENSMSE, Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), MPM-ENSMSE - Département Microstrucutres et Propriétés Mécaniques, Aunt Daisy Scientific Ltd, Aunt Daisy Scientific Ltd, Lydney, Aunt Daisy Scientific Ltd, Lydney-Aunt Daisy Scientific Ltd, Lydney, Materials Division [NPL Teddington], National Physical Laboratory [Teddington] (NPL), BLG Productions, Bristol, BLG Productions Bristol-BLG Productions Bristol, Ecole Nationale Supérieure des Mines, Centre SMS - UMR CNRS 5146, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, BLG Productions Ltd, 3 Sydenham Road, Cotham, Bristol BS6 5SH, UK, 158 cours Fauriel, 42023 Saint Etienne cedex 2, France, Claremont House, High St, Lydney, and Gloucestershire GL15 5DX

Subjects
010302 applied physics, Diffraction, Physics, business.industry, EBSD, Bragg's law, Physics::Optics, Scanning electron microscope, 02 engineering and technology, 021001 nanoscience & nanotechnology, 16. Peace & justice, 01 natural sciences, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Computational physics, Strain, [SPI.MAT]Engineering Sciences [physics]/Materials, Optics, Projection (mathematics), 0103 physical sciences, Calibration, 0210 nano-technology, business, Instrumentation, Electron backscatter diffraction
Abstract

International audience; This comment on the paper "Bragg's Law diffraction simulations for electron backscatter diffraction analysis" by Kacher et al. explains the limitations in determining elastic strains using synthetic EBSD patterns. Of particular importance are those due to the accuracy of determination of the EBSD geometry projection parameters. Additional references and supporting information are provided.

Published
2010

30. Plasticity localization ahead of a crack tip modeled by 2D discrete dislocation dynamics

Author

D. Tanguy, Mialy Razafindrazaka, David Delafosse, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Ecole Mines St Etienne, UMR CNRS 5146, 158 Cours Fauriel, FR-42033 St Etienne, and France

Subjects
Materials science, Misorientation, NICKEL, 02 engineering and technology, Slip (materials science), Plasticity, Cubic crystal system, 01 natural sciences, DUCTILE TRANSITIONS, Physics::Geophysics, [SPI.MAT]Engineering Sciences [physics]/Materials, Crack closure, Condensed Matter::Materials Science, 0103 physical sciences, Computational mechanics, SEGREGATION, 010302 applied physics, EMISSION ARRANGEMENTS, CLEAVAGE, Lüders band, Mechanics, 021001 nanoscience & nanotechnology, Condensed Matter Physics, FRACTURE, Crystallography, EQUILIBRIUM, Hardening (metallurgy), GROWTH, SINGLE-CRYSTALS, 0210 nano-technology, NUCLEATION
Abstract

International audience; The formation of a plastic zone in the presence of a crack, in a bicrystal, is modeled by two-dimensional discrete dislocation dynamics. The influence of a large number of parameters is studied: the misorientation, the emission from the crack tip and the obstacle density which modifies the internal stress (hardening) and degree of localization of mobile dislocations (slip bands). Emphasis is put on obtaining the best ductility, since the focus is on face centered cubic materials. Finally, a strong effect of the plastic model on the dynamics and on the secondary slip (intensity and localization), beyond the influence of the initial distribution of sources and obstacles, is reported.

Published
2010

31. 3D simulation of the matter transport by surface diffusion within a level-set context

Author

François Valdivieso, Sylvain Drapier, Guillaume Pacquaut, Julien Bruchon, Daniel Pino Muñoz, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
Surface (mathematics), level-set method, Boundary (topology), Context (language use), 02 engineering and technology, [SPI.MECA.SOLID]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Solid mechanics [physics.class-ph], Curvature, 01 natural sciences, Level set, Laplace-Beltrami operator, [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], 0101 mathematics, Mathematics, Surface diffusion, sintering process, Mechanical Engineering, Function (mathematics), Mechanics, 021001 nanoscience & nanotechnology, surface diffusion, 010101 applied mathematics, Classical mechanics, Mechanics of Materials, Modeling and Simulation, curvature, 0210 nano-technology, Laplace operator
Abstract

International audience; Within the framework of the sintering process simulation, this paper proposes a numerical strategy for the direct simulation of the matter transport by surface diffusion. A level-set method is used to describe the topological changes which arise at the free boundary of the sintering particles. The surface velocity is found to be proportional to the surface Laplacian of the curvature, that is, proportional to the fourth-order derivative of the level-set function. Consequently, both curvature and velocity must be computed carefully and with accuracy. Finally, three-dimensional simulations are shown and investigated.

Published
2010

32. Reply to 'Comments on 'Modelling differential scanning calorimetry curves of precipitation in Al-Cu-Mg' by MJ Starink and S. Wang

Author

Emmanuel Hersent, Julian H. Driver, David Piot, Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), MPM-ENSMSE - Département Microstrucutres et Propriétés Mécaniques, Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-MPM-ENSMSE - Département Microstructures et Propriétés, and Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE)

Subjects
010302 applied physics, Materials science, Precipitation (chemistry), Mechanical Engineering, Metals and Alloys, Analytical chemistry, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Differential scanning calorimetry, Mechanics of Materials, 0103 physical sciences, General Materials Science, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2010

33. Defect hardening modeled in 2D discrete dislocation dynamics

Author

Mialy Razafindrazaka, David Delafosse, D. Tanguy, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Mécanique physique et interfaces (MPI-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Materials science, Mechanical Engineering, Lüders band, Slip band, 02 engineering and technology, Slip (materials science), Mechanics, Plasticity, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Crystallography, Mechanics of Materials, Obstacle, 0103 physical sciences, Hardening (metallurgy), Hardening, General Materials Science, Dislocation, 010306 general physics, 0210 nano-technology, Discrete dislocation, Dislocation theory
Abstract

International audience; Two-dimensional discrete dislocation dynamics simulations are used to model the plastic deformation of an fcc metallic material containing large densities of defects. An obstacle model is proposed, based on the line tension concept. Increasing yield strength and hardening are obtained when the obstacle density is increased and destroyable junctions are included. A high dislocation source density is used to obtain a good dissemination of dislocations. Over 30% of the total density is stored as junctions. Slip is shown to be localized within a few intense slip bands, whatever the obstacle density. This localization is quantified as a function of the density of obstacles.

Published
2009

34. Effects of Electron Beam Irradiation on Impact Value of Carbon Fiber Reinforced Thermoplastic Polyetheretherketone

Author

Alain Vautrin, Keisuke Iwata, Yoshitake Nishi, Hiroaki Takei, Michelle Salvia, Grad Sch Met Engn, Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Tokai Univ, Grad Sch Met Engn, Tokai univ-Tokai univ-Tokai Univ, Doctoral Grad Sch Sci & Engn, Tokai univ, Tokai Univ, Grad Sch Met Engn, Tokai Univ, Doctoral Grad Sch Sci & Engn, École Centrale de Lyon (ECL), Université de Lyon, Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Thermoplastic, Friction force, Charpy impact test, Value (computer science), 02 engineering and technology, 01 natural sciences, carbon fiber, electron beam irradiation, [SPI.MAT]Engineering Sciences [physics]/Materials, Electron beam irradiation, 0103 physical sciences, General Materials Science, Irradiation, Composite material, thermoplastic, Weibull distribution, 010302 applied physics, chemistry.chemical_classification, Reproducibility, Mechanical Engineering, polyetheretherketone, 021001 nanoscience & nanotechnology, Condensed Matter Physics, impact value, chemistry, Mechanics of Materials, 0210 nano-technology
Abstract

International audience; Homogeneous low voltage electron beam irradiation (HLEBI) improves the Charpy impact value (a(uc)) of composites sheets of carbon fiber reinforced thermoplastic polyetheretherketone (CFRTP) with 2 mm thickness, although the irradiated depth estimated is 177 +/- 32 mu m at their both sides surface. The a(uc) values at low fracture probability (P(f)) of 0.13 for CFRTP irradiated at 0.43 MGy (kJg(-1)) is 78 kJm(-2), which is 56% higher than that (50 kJm(-2)) for CFRTP before irradiation. Although the lowest impact values (a(s)) estimated by three parameters Weibull equation is zero for CFRTP before irradiation, HLEBI enhances the a(s) value. The highest a(s) value is more than 55 kJm(-2) for CFRTP irradiated from 0.43 to 0.65 MGy. Thus, HIEBL remarkably enhances the a(s) value, as well as the a(uc) value at low P(f) value. Since HLEBI enhances the Weibull coefficient (n), it also enhances the reproducibility of CFRTP samples. The maximum it value is found at 0.43 MGy of HLEBI dose. The interfacial friction force, as well as the strengthening of both carbon fiber and polyetheretherketone probably contributes the HLEBI effects to enhance the a(s) value of CFRTP, as well as enhancement of reproducibility.

Published
2009

35. On twinning and shear banding in a Cu–8 at.% Al alloy plane strain compressed at 77 K

Author

Adam Morawiec, Julian H. Driver, Emmanuel Bouzy, Henryk Paul, Institute of Metallurgy and Materials Science, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire d'étude des textures et application aux matériaux (LETAM), and Université Paul Verlaine - Metz (UPVM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 02 engineering and technology, Slip (materials science), [SPI.MAT]Engineering Sciences [physics]/Materials, Condensed Matter::Materials Science, 0203 mechanical engineering, Stacking-fault energy, Deformation twinning, General Materials Science, Texture, Plane stress, Condensed matter physics, Mechanical Engineering, 021001 nanoscience & nanotechnology, Microstructure, Copper–aluminium alloy, Shear bands, Crystallography, 020303 mechanical engineering & transports, Shear (geology), Mechanics of Materials, 0210 nano-technology, Crystal twinning, TEM orientation mapping, Shear band, Single crystal
Abstract

Crystal lattice rotations induced by twinning and shear banding developed in a Cu–8 at.% Al alloy (representative of fcc metals with low stacking fault energy) have been examined in order to investigate the influence of bands on slip propagation across a structure of twin-matrix layers and the resulting texture evolution. The microstructure and texture of ( 1 1 2 ) [ 1 1 1 ¯ ] oriented single crystal plane strain compressed up to ∼80% 77 K were characterized by transmission electron microscopy (TEM) including TEM orientation mapping. It is shown that the strong, initial texture changes are due to deformation twinning. Two families of deformation twins, symmetric with respect to the plane perpendicular to the extension direction, are observed. However, only one of them plays a dominant role in strain accommodation. At larger deformations, twin-matrix deflection within some narrow areas leads to kink-type bands, and this is crucial for understanding further texture transformations. The kink bands are precursors of shear bands (SB). It is shown by detailed TEM orientation mapping how the structure of twins and matrix is incorporated into a SB, and what kind of the dislocation mechanisms are responsible for strain accommodation at the macro-scale. It was found that the re-orientation of the main (1 1 1) twinning planes towards the SB plane facilitates further dislocation slip in the shear direction. Finally, a crystallographic description of SB formation in completely twinned fcc metals is proposed based on lattice re-orientations due to localized kinking.

Published
2009

36. Mesoscopic Investigation of the Heterogeneities Induced by Channel-Die Compression

Author

Ahmed Chenaoui, René-Yves Fillit, Michel Darrieulat, Khalid Zhani, Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Laboratoire d'Energétique et Mécanique des Fluides et Sciences des matériaux, and Université Abdelmalek Essaâdi (UAE)

Subjects
plastic deformation, Engineering drawing, Materials science, fiducial grids, Geometry, 02 engineering and technology, Plasticity, mesoscopic scale, [SPI.MAT]Engineering Sciences [physics]/Materials, 0203 mechanical engineering, Lattice (order), General Materials Science, zinc alloys, copper alloys, Mesoscopic physics, Mechanical Engineering, Slip band, microfocus X-rays, Strain hardening exponent, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Grid, X-ray diffraction, 020303 mechanical engineering & transports, Mechanics of Materials, copper, plasticity, 0210 nano-technology, X-ray analysis
Abstract

International audience; Experimental techniques were applied to study the heterogeneities of deformation of metals at the mesoscopic scale (typically 100µm in the present case). The first are fiducial carbon grids that are transferred on to the surface of the test-pieces. Here, they were used on single and polycrystals deformed in channel-die compression. They prove efficient for strains above 1. They bring out the role of the corners of the samples, which trigger bands of deformation that grow in importance as the compression goes on. They put in evidence the mesoheterogeneities that appear in the mechanical behavior of a few highly symmetric orientations such as cube. The second technique is the use of microfocused X-rays, which give the crystallographic orientation at the same scale of 100µm and can work in the presence of the carbon grids even when there is considerable strain hardening. The gradients found in the lattice rotations are far less pronounced than the sharp localizations in the displacement field. This highlights the importance of the rotations due to the activity of the slip systems.

Published
2009

37. Bayesian Statistical Identification of Orthotropic Elastic Constants Accounting for Measurement and Modeling Errors

Author

Christian Gogu, Raphael T. Haftka, Rodolphe Le Riche, Jérôme Molimard, Alain Vautrin, Bhavani V. Sankar, Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Département d'Ingénierie Mécanique et Aérospatiale, University of Florida [Gainesville] (UF), Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical and Aerospace Engineering [Gainesville] (UF|MAE), Equipe : Calcul de Risque, Optimisation et Calage par Utilisation de Simulateurs (CROCUS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-UR LSTI, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Institut Mines-Télécom [Paris] (IMT), Centre Sciences, Information et Technologies pour l'Environnement (SITE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Département Décision en Entreprise : Modélisation, Optimisation (DEMO-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Henri Fayol, and Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Bayesian probability, [INFO.INFO-DS]Computer Science [cs]/Data Structures and Algorithms [cs.DS], 02 engineering and technology, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], 021001 nanoscience & nanotechnology, Orthotropic material, [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, [SPI.MAT]Engineering Sciences [physics]/Materials, Identification (information), 020303 mechanical engineering & transports, 0203 mechanical engineering, Applied mathematics, 0210 nano-technology
Abstract

International audience; Bayesian identification provides a framework that can handle both measurement and modeling errors. Furthermore it identifies a probability distribution function thus providing information on both variance and correlation of the identified properties. However, the procedure can be very costly computationally. In order to address the computational cost issue a Bayesian identification procedure based on response surface methodology is proposed. The procedure is illustrated on the problem of identifying orthotropic elastic constants from natural frequencies of a free composite plate. The procedure accounts for measurement noise, uncertainty in other input parameters to the vibration model (plate dimensions, density) as well as systematic error effects. The joint probability distribution of the four elastic ply constants is identified and characterized by mean value and variancecovariance matrix. We find that some properties, such as Poisson's ratio, are identified with much higher uncertainty than other and that significant correlation between the identified properties is present. The developed procedure allowed substantial reduction in computational cost. However, in spite of the cost reduction techniques, it remains at the edge of what is presently reasonable computation time.

Published
2009

38. Sub-grain boundary mobilities during recovery of binary Al-Mn alloys

Author

Fabrice Barou, Claire Maurice, Julian H. Driver, Jean-Marie Feppon, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Alcan Centre de Recherches de Voreppe, and Alcan

Subjects
Materials science, Annealing (metallurgy), Scanning electron microscope, Analytical chemistry, 02 engineering and technology, Activation energy, 01 natural sciences, Sub-boundary mobilities, [SPI.MAT]Engineering Sciences [physics]/Materials, Al-Mn alloys, Recovery, 0103 physical sciences, Materials Chemistry, SEM/EBSD, Physical and Theoretical Chemistry, 010302 applied physics, Metals and Alloys, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Crystallography, Electron diffraction, Grain boundary, Activation energies, 0210 nano-technology, Electron backscatter diffraction
Abstract

The influence of Mn solute atoms on sub-grain boundary mobilities in Al has been determined by accurate electron backscatter diffraction analysis of the sub-grain sizes and misorientations during recovery annealing. High purity Al-0.1 and 0.3 wt.% Mn alloys were deformed by plane strain compression at room temperature to equivalent strains of 1.8 and annealed in the temperature range 150 – 300 °C. An original method of image analysis on sub-boundaries from electron backscatter diffraction maps was applied to quantify the sub-grain size distributions. The change in average sub-grain size with time at several temperatures was then used to estimate sub-grain boundary mobilities in both Al – Mn alloys. The activation energies for sub-grain mobility were found to be 48 and 52 and kJ mol– 1 for the 0.1 and 0.3 % Mn alloys respectively, with the higher Mn alloy exhibiting lower rates. The sub-boundary mobilities are higher than expected from previous similar work on deformed Al – Si crystals. The orientation dependence of sub-grain growth is also examined.

Published
2009

39. A grain scale approach for modeling steady-state discontinuous dynamic recrystallization

Author

Frank Montheillet, O. Lurdos, G. Damamme, Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Materials science, Polymers and Plastics, Nucleation, Dynamic recrystallization, 02 engineering and technology, Flow stress, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Hot working, Grain-boundary migration, Analytical methods, 0103 physical sciences, Softening, 010302 applied physics, Steady state, Metallurgy, Metals and Alloys, Modeling, Mechanics, Strain hardening exponent, 021001 nanoscience & nanotechnology, Electronic, Optical and Magnetic Materials, Ceramics and Composites, Grain boundary, 0210 nano-technology
Abstract

International audience; Discontinuous dynamic recrystallization (DDRX) generally occurs in low-stacking-fault-energy metals. New grains nucleate and grow at the expense of the strain-hardened older grains. A steady-state flow stress independent of initial conditions is experimentally observed. A general model is proposed to describe these phenomena. While the transient behavior can be addressed only numerically, a steady state is described in detail by closed-form relationships. The approach includes strain hardening and dynamic recovery, nucleation, growth and shrinkage of grains. Furthermore, the strain-hardening equation can be supplemented to account for the effect of boundary-migration-induced softening (BMIS). The present paper first states the general equations of the model; some simple strain-hardening laws neglecting BMIS are then discussed. Finally, a method for evaluating the material parameters is described and illustrated by the example of 304L stainless steel.

Published
2009

40. Oxidation of a chromia-forming nickel base alloy at high temperature in mixed diluted CO/H2O atmospheres

Author

Michèle Pijolat, Céline Cabet, Krzysztof Wolski, Fabien Rouillard, Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Procédés et évolution des systèmes avec solides (ProcESS-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Reactor conditions, Materials science, 020209 energy, General Chemical Engineering, Alloy, Kinetics, Inorganic chemistry, Oxide, 02 engineering and technology, engineering.material, Corrosion, [SPI.MAT]Engineering Sciences [physics]/Materials, Metal, chemistry.chemical_compound, Oxidation, 0202 electrical engineering, electronic engineering, information engineering, General Materials Science, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Superalloys, High-temperature corrosion, Metallurgy, General Chemistry, 021001 nanoscience & nanotechnology, Chromia, Superalloy, High temperature Corrosion, chemistry, visual_art, engineering, visual_art.visual_art_medium, 0210 nano-technology, SIMS
Abstract

International audience; Corrosion of a chromia-forming nickel base alloy, Haynes 230_, has been investigated under impure helium containing a few Pa of CO and H2O at 900 °C. It has been found that this alloy reacts simultaneously with CO and H2O. Oxidation by CO has been revealed to occur mainly in the first hours. CO diffuses through the scale via short-circuit pathways and oxidizes Al, Cr and Si at the oxide/metal interface. Kinetics of CO oxidation has been investigated and several rate limiting steps are proposed. In the long term, H2O is the major oxidant of chromia-forming nickel base alloys in impure helium.

Published
2009

41. Stress concentrations in non-convex elastic particles embedded in a ductile matrix

Author

Helmut Klocker, Nicolas Moulin, Dominique Jeulin, Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), Centre de Morphologie Mathématique (CMM), MINES ParisTech - École nationale supérieure des mines de Paris-PSL Research University (PSL), UMR 5146 - Laboratoire Claude Goux (LCG-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre Science des Matériaux et des Structures (SMS-ENSMSE), Department of Material Sciences and Structures (SMS), CNRS-UMR 5146, 77305 Fontainebleau Cedex, Ecole des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 Saint-Etienne Cedex 2, France, MINES Paristech, CMM-Centre de Morphologie Mathématique, Mathématiques et Systèmes, and 35 Rue Saint Honoré

Subjects
inter-metallic particle, Materials science, BOUNDS, Failure, 02 engineering and technology, INCLUSION, MODULI, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, Brittleness, DEFORMATION, 0103 physical sciences, General Materials Science, Composite material, Stress concentration, Plane stress, 010302 applied physics, Mechanical Engineering, METAL CERAMIC COMPOSITES, Stress–strain curve, General Engineering, BEHAVIOUR, 021001 nanoscience & nanotechnology, INHOMOGENEOUS SYSTEMS, Mechanics of Materials, Casting (metalworking), MECHANICS, Particle, Particle size, Deformation (engineering), 0210 nano-technology, X-ray tomography, Finite element model
Abstract

International audience; Aluminium sheet is currently used for body panels on a number of mass-produced vehicles, in particular for closure panels. AA5xxx alloys always contain coarse inter-metallic particles (Alx(Fe,Mn)ySi, Mg2Si) after casting, undesirable for the final sheet forming and stamping operations. In the present work inter-metallic particle break-up during hot reversible rolling of AA5182 alloy sheets has been analysed by both experiments and by a micromechanical model. The sizes and shapes of inter-metallic particles in as cast and industrially hot rolled AA5182 alloys sheets were characterised by 3D X-ray tomography observations. The evolution of inter-metallic particle size and shape vs. hot rolling deformation was studied. The stresses and strains in inter-metallic particles, embedded in an elasto-viscoplastic aluminium matrix submitted to plane strain compression, were analysed by a finite element (FE) model. First, the mechanisms leading to stress and strain concentrations were analysed on several model particle shapes. A new algorithm for FE-analysis of stress concentrations around hard second phase particles in Al alloys was developed. A new failure criterion for brittle pre-cracked solids embedded in a soft matrix submitted to large straining was proposed. Secondly, this new algorithm and the new failure criterion were used to analyse the stress and strain concentrations in the real particles observed by X-ray tomography. The ability to break-up of the particles was analysed. The essential outcomes of the present work are as follows: a precise description of stress concentration mechanisms in non-convex particles, a new failure criterion based on the comparison between an active and a critical volume, a close description of the parameters controlling particle break-up, and finally a classification of the failure behaviour of real inter-metallic particles.

Published
2009

42. A mechanical analysis of metallic tritide aging by helium bubble growth

Author

S. Thiébaut, E. Munier, A. Fabre, D. Delaplanche, Frank Montheillet, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Rhéologie, Microstructure, Thermomécanique (RMT-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, VALDUC (DAM/VALDUC), Direction des Applications Militaires (DAM), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Materials science, Diffusion, Bubble, chemistry.chemical_element, Thermodynamics, Young's modulus, 02 engineering and technology, 01 natural sciences, 010305 fluids & plasmas, Moduli, [SPI.MAT]Engineering Sciences [physics]/Materials, symbols.namesake, Analytical methods, 0103 physical sciences, General Materials Science, Elastic modulus, Helium, Viscoplasticity, Continuum mechanics, Mechanical Engineering, Hydrides, Radius, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Damage, PALLADIUM TRITIDE, chemistry, Mechanics of Materials, symbols, TEM, 0210 nano-technology, STORAGE
Abstract

International audience; A simple mechanical model is proposed for the aging of a metallic tritide. The material is assumed to be elastic-power law viscoplastic. Part of the helium atoms generated by tritium decay form spherical bubbles that weaken the elastic moduli of the overall material. By contrast others can be stored in solid, solution in the matrix and are likely to increase the moduli. Two variants of the model are compared, assuming either instantaneous or finite rate diffusion of helium. They predict globally similar evolutions of the gas pressure inside the bubbles, the geometrical parameters (bubble radius, overall swelling), as well as the matrix and overall elastic moduli. The results are in good agreement with atomistic calculations of the pressure evolution. Furthermore, recent experimental measurements of the Young modulus changes during aging are better reproduced when He diffusion rate is finite, thus supporting the second variant of the model.

Published
2008

43. Rotation axis analysis of deformed crystals by X-rays and electrons

Author

András Borbély, Claire Maurice, Julian H. Driver, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Gesellschaft, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Diffraction, SUBGRAIN GROWTH, Materials science, MISORIENTATIONS, Misorientation, COPPER SINGLE-CRYSTALS, 02 engineering and technology, Slip (materials science), Electron, DIFFRACTION, 01 natural sciences, General Biochemistry, Genetics and Molecular Biology, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, Condensed Matter::Materials Science, Optics, DEFORMATION, Condensed Matter::Superconductivity, 0103 physical sciences, 010302 applied physics, Condensed matter physics, business.industry, BOUNDARIES, 021001 nanoscience & nanotechnology, chemistry, RESOLUTION, X-ray crystallography, PATTERNS, Specific rotation, Crystallite, 0210 nano-technology, business, Electron backscatter diffraction
Abstract

International audience; X-ray and electron backscatter diffraction (EBSD) have been applied to investigate misorientation distributions in copper single crystals plastically deformed in single and multiple slip. The misorientation distributions are represented by 'rocking curves' about specific rotation axes. Very good agreement for the rocking curves established by the two methods was obtained, despite the large difference between their resolution depths. Following this agreement, a new rotation axis imaging scheme, based on the EBSD data, is proposed in order to visualize the crystallite blocks and characterize the nature of their dislocation boundaries.

Published
2008

44. An interface debonding law subject to viscous regularization for avoiding instability: Application to the delamination problems

Author

Mostapha Tarfaoui, A. Vautrin, Lofti Hamitouche, Laboratoire brestois de mécanique et des systèmes (LBMS), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Mécanique et Procédés d'Elaboration (MPE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire de Tribologie et Dynamique des Systèmes (LTDS), École Centrale de Lyon (ECL), and Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, PREDICTION, Bilinear interpolation, 02 engineering and technology, Instability, [SPI.MAT]Engineering Sciences [physics]/Materials, Fracture toughness, 0203 mechanical engineering, Cohesive zone, COMPOSITES, General Materials Science, Viscous regularization, DCB, business.industry, Mechanical Engineering, DAMAGE MODEL, Fracture mechanics, LOCALIZATION, Structural engineering, Mechanics, 021001 nanoscience & nanotechnology, Finite element method, Cohesive zone model, 020303 mechanical engineering & transports, Mechanics of Materials, Regularization (physics), Delamination, SIMULATION, GROWTH, 0210 nano-technology, business, MESOMODEL, Numerical stability
Abstract

International audience; The prediction of ply delamination in laminated composites is modeled by using interface elements. The numerical approach is based on the cohesive zone model, which is shown to provide an efficient description of the delamination growth. The theoretical study is performed in quasi-static regime and an implicit finite element scheme is used. A comprehensive I D example shows that cohesive elements may induce numerical instability and that the use of a viscous regularization is relevant to suppress the instability and to obtain a reasonable numerical convergence. This paper describes a technique that can be used to introduce damping into cohesive zone finite element simulations of crack nucleation and growth, with a view to avoiding convergence difficulties in quasi-static finite element simulations. A new kind of viscous regularization is proposed, which applies to the bilinear debonding model and has a limited rate dependency. An experimental study is performed by using DCB (double cantilever beam) samples for the mode I interlaminar fracture toughness test; a good agreement between numerical predictions and experimental results is obtained. (c) 2007 Elsevier Ltd. All rights reserved.

Published
2008

45. Strain hardening and microstructure evolution of channel-die compressed aluminium bicrystals

Author

Henryk Paul, W. Wajda, Julian H. Driver, Institute of Metallurgy and Materials Science, Polska Akademia Nauk = Polish Academy of Sciences (PAN), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS

Subjects
Materials science, bicrystals, 02 engineering and technology, 01 natural sciences, MECHANISMS, [SPI.MAT]Engineering Sciences [physics]/Materials, Condensed Matter::Materials Science, DEFORMATION, 0103 physical sciences, General Materials Science, Composite material, Grain boundary strengthening, Plane stress, 010302 applied physics, FEM, strain hardening, Mechanical Engineering, aluminium, Metallurgy, Strain hardening exponent, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Mechanics of Materials, microstructures, Metallography, Hardening (metallurgy), Substructure, Grain boundary, SINGLE-CRYSTALS, ORIENTATION, 0210 nano-technology, strain heterogeneities, Electron backscatter diffraction
Abstract

International audience; The different types of strain heterogeneities developed in pure aluminium bicrystals during plane strain compression have been characterized by advanced metallographic techniques over several length scales. Bicrystals, with three grain orientation combinations (one hard/soft, and two stable/unstable) containing grain boundaries perpendicular to the compression axis, were deformed up to strains of 1.5 at 77 K and their deformation substructure investigated by optical microscopy, high resolution EBSD and transmission electron microscopy. At the macroscopic scale the hard/soft combination develops major strain variations as the softer grain flows out over the harder grain. This is consistent with finite element simulations of bicrystal deformation using the appropriate individual grain hardening laws and leads to a large transition zone near the boundary. At the microscopic level, the grains of the other combinations behave essentially as single crystals under the same deformation conditions, in particular with respect to the deformation substructure and microtexture distributions. It is concluded that for most grain pair combinations of deformed bicrystals the individual grain orientations play a dominant role in deformation substructure development as a consequence of their dependence on slip system interactions. (c) 2007 Elsevier B.V. All rights reserved.

Published
2008

46. Three-dimensional microtomographic study of Widmanstätten microstructures in an alpha/beta titanium alloy

Author

Eric Maire, Maxime Moreaud, Michel Darrieulat, Dominique Jeulin, F. Montheillet, Nicolas Vanderesse, Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Centre des Matériaux (MAT), MINES ParisTech - École nationale supérieure des mines de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 02 engineering and technology, 01 natural sciences, Image analysis, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, Titanium alloys, General Materials Science, Segmentation, Composite material, 010302 applied physics, Orientation (computer vision), Mechanical Engineering, Metallurgy, Aggregate (data warehouse), Metals and Alloys, Titanium alloy, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Microstructure, Beta titanium alloy, Alpha (programming language), Mechanics of Materials, 3d image, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 0210 nano-technology, X-ray tomography
Abstract

International audience; A beta-quenched titanium alloy was studied by means of microtomography. This technique provides three dimensional (3D) representations of the microstructure. It appears that the colonies have non-convex shapes and form an intricate aggregate. An algorithm of 3D image segmentation based on the orientation of the lamellae is presented. Its results are in agreement with those derived from a manual segmentation method, and allow the colonies to be examined individually. Further perspectives on the basis of this experiment are outlined.

Published
2008

47. Modeling for temperature compensation and temperature characterizations of BAW resonators at GHz frequencies

Author

Ph. Benech, R.Y. Fillit, F. Ndagijimana, P. Ancey, G. Parat, Brice Ivira, Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation (IMEP-LAHC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, STMicroelectronics [Crolles] (ST-CROLLES), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE)

Subjects
Permittivity, Electromechanical coupling coefficient, frequency temperature coefficient, dielectric permittivity, Materials science, Piezoelectric coefficient, Acoustics and Ultrasonics, Piezoelectric sensor, BAW resonators, Acoustics, quality factors, 02 engineering and technology, Dielectric, stiffness coefficient, 01 natural sciences, mass-loading deposition, temperature compensation, [SPI.MAT]Engineering Sciences [physics]/Materials, 0103 physical sciences, bulk acoustic wave devices, piezoelectric coefficient, Electrical and Electronic Engineering, Instrumentation, electrode thin film thicknesses, 010302 applied physics, antiresonance frequency, solidly mounted resonators, acoustic resonators, TUNGSTEN, piezoelectricity, Q-factor, frequency 2 GHz, Atmospheric temperature range, 021001 nanoscience & nanotechnology, Antiresonance, permittivity, electromechanical coupling factors, [SPI.ELEC]Engineering Sciences [physics]/Electromagnetism, elasticity, 0210 nano-technology, Temperature coefficient
Abstract

International audience; This paper deals with the temperature dependence of electrical and physical features of various kinds of solidly mounted resonators (SMR). The presented bulk acoustic wave (BAW) devices are designed for the 2 GHz application. The temperature coefficient of frequency (TCF) is determined from measurements well above the temperature range defined for wireless telecommunication system specifications. Therefore, evolution of electromechanical coupling factors and quality factors at resonance and antiresonance are also monitored. Results of characterizations show the trend for a subsequent theoretical temperature compensation study by using analytical modeling. To improve accuracy of modeling, an attempt to extract temperature dependence of dielectric permittivity epsilon(33) and piezoelectric coefficient epsilon(33) is made. Finally, a well-known analytical model is modified to take into account the temperature dependence of length, density, stiffness coefficient, dielectric permittivity, and piezoelectric coefficient. Modeling highlights the need to deposit a material with positive temperature coefficient of stiffness on the top electrode. Realistic thickness of such a layer is determined. At the same time, it is necessary to adjust piezoelectric and electrode thin film thicknesses for simultaneously keeping a constant antiresonance frequency, reaching a zero temperature coefficient of frequency for antiresonance, and minimizing the decrease in the coupling factor because of the mass-loading deposition.

Published
2008

48. One-step deposition of diamond-like carbon films containing self-assembled metallic nanoparticles, by femtosecond pulsed laser ablation

Author

Nadia Benchikh, Alain Pailleret, Christophe Donnet, Jean-Noël Rouzaud, Florence Garrelie, René-Yves Fillit, J.Y. Laval, Laboratoire Hubert Curien (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Propriétés Mécaniques (MPM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire de Physique du Solide (LPS), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interfaces et Systèmes Electrochimiques (LISE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Hubert Curien [Saint Etienne] (LHC), Institut d'Optique Graduate School (IOGS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), and Centre National de la Recherche Scientifique (CNRS)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris)

Subjects
Materials science, Diamond-like carbon, NANOSECOND, Tantalum, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, 01 natural sciences, HIP JOINTS, Pulsed laser deposition, law.invention, [SPI.MAT]Engineering Sciences [physics]/Materials, THIN-FILMS, law, AMORPHOUS-CARBON, 0103 physical sciences, Deposition (phase transition), General Materials Science, Thin film, TANTALUM, 010302 applied physics, General Chemistry, 021001 nanoscience & nanotechnology, Laser, Carbon film, CARBIDE, chemistry, Amorphous carbon, VACUUM, GROWTH, 0210 nano-technology
Abstract

International audience; Femtosecond pulsed laser ablation has been used for the deposition of various thin films by co-ablating pure graphite and pure metallic targets (nickel or tantalum) under vacuum conditions with an amplified Ti:sapphire laser working at 800 nm, with about 1.5 mJ per pulse at a repetition rate of 1 kHz. The plasma plume created during the femtosecond pulsed laser deposition process has been investigated, by fast imaging and spectroscopic characterizations, depending on the ablated target and deposition conditions. Particular attention has been paid to the correlation between the film nanostructure and the plasma plume properties, in terms of ejected species and energies of impinging species on the substrate. The tantalum clusters in the tantalum-doped carbon films appear under two crystalline phases: a stable phase (alpha-Ta) corresponding to that of the target, and a metastable phase (beta-Ta), already observed at high temperatures. The presence of this metastable phase (beta-Ta) is correlated to the temperature of the clusters measured from the plasma plume investigation.

Published
2008

49. Comparison of the high temperature surface reactivity in impure helium of two materials for gas cooled reactors

Author

Céline Cabet, Krzysztof Wolski, Fabien Rouillard, Gouenou Girardin, Jerome Chapovaloff, Michèle Pijolat, Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Corrosion Chemistry Dept, AREVA NP - Centre Technique (FRANCE), Département Mécanique physique et interfaces (MPI-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département Procédés et évolution des systèmes avec solides (ProcESS-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN

Subjects
Materials science, INCONEL ALLOY 617, Alloy, chemistry.chemical_element, reduction, 02 engineering and technology, engineering.material, 01 natural sciences, 7. Clean energy, [SPI.MAT]Engineering Sciences [physics]/Materials, chemistry.chemical_compound, Impurity, SYSTEMS, 0103 physical sciences, General Materials Science, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Inconel, nickel base alloy, Helium, 010302 applied physics, Mechanical Engineering, carbon, Metallurgy, IMPURITIES, Partial pressure, CORROSION, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Chromia, chemistry, Mechanics of Materials, engineering, chromia, chromium, 0210 nano-technology, Carbon, Carbon monoxide
Abstract

International audience; Nickel base alloys Haynes 230 and Inconel 617 are of interest for gas cooled reactors. At high temperature in impure helium, they generally form surface chromium-rich oxides. However above a critical temperature called T-A, the scales are not stable anymore and the chromia destruction comes with a production of carbon monoxide. Reactivity tests on model alloys, with and without carbon, prove that chromia is reduced by the carbon from the alloy. TA VS P(CO) curves were also plotted for the two commercial alloys based on the experimental determination of T-A in various atmospheres with increasing partial pressures of carbon monoxide. Unexpectedly, both materials exhibit an almost ideatical behavior although a basic equilibrium approach suggests that the chromia scale would be reduced in different conditions due to the thermodynamic particularity of the interfacial alloy/scale system.

Published
2008

50. Experimental identification and characterization of the effects of contaminants in the wheel-rail contact

Author

Sylvie Descartes, Yves Berthier, Christophe Desrayaud, Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne] (LaMCoS), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Département Microstructures et Traitements Thermomécaniques (MTT-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS, Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), and Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS)

Subjects
Ballast, Engineering, Third body, third body, friction, real-time visualization, 02 engineering and technology, [SPI.MAT]Engineering Sciences [physics]/Materials, 0203 mechanical engineering, interfacial layer, business.industry, Mechanical Engineering, Mechanics, Structural engineering, Tribology, Contamination, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], 021001 nanoscience & nanotechnology, Characterization (materials science), wheel-rail contact, Real time visualization, Boundary layer, 020303 mechanical engineering & transports, contaminants, 0210 nano-technology, business, Layer (electronics)
Abstract

Previous results have highlighted the presence of a natural third body ranging in thickness from a few micrometres to several dozen micrometres on the rail and wheel. The third body layer, initially composed of particles stemming from the wheels and rails, flows into the contact to accommodate local sliding inside it. The work presented in this paper focuses on the identification of contaminants whose influence on the wheel—rail contact is significant. This influence can be considered as significant if it enters the contact, affects surface properties, modifies the third body layer, and possibly damages or protects the rail. The third body layer can progressively absorb and assimilate solid (ballast stone, sand) and fluid (oil) contaminants existing on rails, and thus reduce their negative consequences on rail lifetime. These phenomena are the result of the exchange of third body flows between the wheel and rail. A high-speed camera was used for this experimental study performed on a real site. The analyses of the dynamic images are coupled with tribological analyses of the surfaces by scanning electron microscopy and X-ray energy dispersive analysis.

Published
2008

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