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38 results on '"Bochtler, Benedikt"'

1. Disentangling structural and kinetic components of the {\alpha}-relaxation in supercooled metallic liquids

Author

Neuber, Nico, Gross, Oliver, Frey, Maximilian, Bochtler, Benedikt, Kuball, Alexander, Hechler, Simon, Yang, Fan, Pineda, Eloi, Westermeier, Fabian, Sprung, Michael, Gallino, Isabella, Busch, Ralf, and Ruta, Beatrice

Subjects
Condensed Matter - Materials Science, Condensed Matter - Disordered Systems and Neural Networks
Abstract

The particle motion associated to the {\alpha}-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron techniques, we found the existence of microscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and Pd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and kinetic contributions to the {\alpha}-process. While the two alloys show similar kinetic fragilities, their structural fragilities differ and correlate with the temperature dependence of the stretching parameter describing the decay of the density fluctuations. This implies that the evolution of dynamical heterogeneities in supercooled alloys is determined by the rigidity of the melt structure. We find also that the atomic motion not only reflects the topological order but also the chemical short-range order, which can lead to a surprising slowdown of the {\alpha}-process at the mesoscopic length scale. These results will contribute to the comprehension of the glass transition, which is still missing.

Published
2022

16. Ni-Nb-P-based bulk glass-forming alloys: Superior material properties combined in one alloy family

Author

Ruschel, Lucas M., primary, Gross, Oliver, additional, Bochtler, Benedikt, additional, Li, Bosong, additional, Adam, Bastian, additional, Neuber, Nico, additional, Frey, Maximilian, additional, Jakovlev, Sergej, additional, Yang, Fan, additional, Jiang, Hao-Ran, additional, Gludovatz, Bernd, additional, Kruzic, Jamie J., additional, and Busch, Ralf, additional

Published
2023
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23. Disentangling structural and kinetic components of the a-relaxation in supercooled metallic liquids

Author

Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. PTP-GlaDyM - Phase transitions, polymorphism, glasses and dynamics of the metastability, Neuber, Nico, Gross, Oliver, Frey, Maximilian, Bochtler, Benedikt, Kuball, Alexander, Hechler, Simon, Yang, Fan, Pineda Soler, Eloi, Westermeier, Fabian, Sprung, Michael, Schäfer, Florian, Gallino, Isabella, Busch, Ralf, Ruta, Beatrice, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. PTP-GlaDyM - Phase transitions, polymorphism, glasses and dynamics of the metastability, Neuber, Nico, Gross, Oliver, Frey, Maximilian, Bochtler, Benedikt, Kuball, Alexander, Hechler, Simon, Yang, Fan, Pineda Soler, Eloi, Westermeier, Fabian, Sprung, Michael, Schäfer, Florian, Gallino, Isabella, Busch, Ralf, and Ruta, Beatrice

Abstract

The particle motion associated to the a-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron tech- niques, we report the existence of microscopic structure-dynamics relationships in Pt42.5 Cu27 Ni 9.5P 21 and Pd 42.5Cu 27 Ni9.5 P21 liquids which allows us to disentangle structural and kinetic contributions to the a-process. While the two alloys show similar kinetic fragilities, their structural fragilities differ and correlate with the temperature dependence of the stretching parameter describing the decay of the density fluctuations. This implies that the evolution of dynamical heterogeneities in supercooled alloys is determined by the rigidity of the melt structure. We find also that the atomic motion not only reflects the topological order but also the chemical short-range order, which can lead to a surprising slowdown of the a- process at the mesoscopic length scale. These results will contribute to the comprehension of the glass transition, which is still missing., We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III beamline P02.1 and we would like to thank Alexander Schoekel and Michael Wharmby for assistance. Further we want to thank our colleagues B. Adam, L. Ruschel, S.S. Riegler, H. Jiang, V. Lemkova, H. Voigt and J. Schmauch for collaboration and fruitful discussions concerning the topic. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and inno- vation programme (Grant Agreement No 948780). The research activity has been sup- ported by the project CALIPSOplus under the Grant 307 Agreement 730872 from the EU Framework Program for Research 308 and Innovation HORIZON 2020. The authors declare that they have no competing interests. All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials., Peer Reviewed, Postprint (published version)

Published
2022

25. Changes in the crystallization sequence upon sulfur addition in the Zr$_{52.5}$Cu$_{17.9}$Ni$_{14.6}$Al$_{10}$Ti$_{5}$ bulk metallic glass-forming liquid revealed by in situ high-energy x-ray diffraction

Author

Bochtler, Benedikt, Mari��o-Salguero, Jessica Marcela, Kuball, Alexander, Gross, Oliver, Yang, Fan, Meyer, Andreas, Buslaps, Thomas, R��tt, Uta, and Busch, Ralf

Subjects
sulfur bearing alloys, Bulk metallic glass, synchrotron diffraction, ddc:530
Abstract

Physical review materials 5(10), 103402 (2021). doi:10.1103/PhysRevMaterials.5.103402, Bulk metallic glasses (BMGs) surpass the strength of steels and possess the elasticity and formability of polymers. The key to obtain these properties is to conserve the amorphous structure of a metallic melt and avoid crystallization during processing. In this work, a change in the crystallization sequence in the widely used BMG Zr$_{52.5}$Cu$_{17.9}$Ni$_{14.6}$Al$_{10}$Ti$_{5}$ (Vit105) upon the addition of sulfur (Zr$_{51.45}$Cu$_{17.54}$Ni$_{14.31}$Al$_{9.8}$Ti$_{4.9}$S$_2$; Vit105 S$_2$) is revealed by in situ high-energy x-ray diffraction, both upon heating from the glassy state and upon cooling from the liquid state during electrostatic levitation. This methodology proves to be a powerful tool to elucidate the complete crystallization behavior of complex BMG-forming liquids. The experiments show that the addition of sulfur changes the crystallization sequence and phases in a different manner upon cooling from the liquid state than upon heating from the glassy state. The thermal stability at low temperatures upon heating is increased, as the supercooled liquid region is extended from 60 to 77 K and the glass transition temperature increases from 671 to 692 K. However, the thermal stability is decreased upon cooling, causing a reduced glass-forming ability., Published by APS, College Park, MD

Published
2021

36. Indications for a fragile-to-strong transition in the high- and low-temperature viscosity of the Fe43Cr16Mo16C15B10 bulk metallic glass-forming alloy.

Author

Bochtler, Benedikt, Gross, Oliver, and Busch, Ralf

Subjects
*VISCOSITY, *GLASS transitions, *THERMOMECHANICAL treatment, *REDUCED gravity environments, *SUPERCOOLED liquids
Abstract

Viscosity of the Fe-based bulk metallic glass-forming liquid Fe43Cr16Mo16C15B10 is measured around the glass transition and in the stable liquid. Low-temperature measurements are conducted using three-point beam bending in a thermomechanical analyzer, and high-temperature data are obtained from the damping behavior of an oscillating droplet which is electromagnetically levitated in microgravity on a reduced-gravity aircraft. The alloy displays an intermediately strong liquid behavior (D*=15.1) at low temperatures and a fragile behavior (D*=7.9) at high temperatures. Hence, the temperature dependence of viscosity changes drastically between the high- and the lowtemperature regime, which suggests the existence of a fragile-to-strong liquid-liquid transition in the supercooled liquid. Furthermore, viscosity and fragility data are discussed with respect to the glass-forming ability of the alloy. [ABSTRACT FROM AUTHOR]

Published
2017
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38. Thermophysical and structural investigations of a CuTi- and a Zr-based bulk metallic glass, the influence of minor additions, and the relation to thermoplastic forming

Author

Bochtler, Benedikt

Abstract

Bulk metallic glasses (BMGs) surpass the strength of steels and at the same time possess the elasticity and formability of thermoplastic polymers. These favorable properties make them interesting candidates for industrial applications. In this work, the thermophysical properties and the structure of the CuTi-based BMG Vit101 (Cu47Ti34Zr11Ni8) and the Zr-based BMG Vit105 (Zr52.5Cu17.9Ni14.6Al10Ti5) are investigated. Special focus lies on the influence of minor additions of sulfur and phosphorus, as they increase the thermal stability of the alloys in the supercooled liquid region. The thermodynamic functions of the alloys are determined, and viscosity and kinetic fragility are measured around the glass transition and in the stable liquid. In-situ synchrotron X-ray scattering experiments are performed, elucidating the crystallization sequence upon heating and cooling. Minor additions retard the formation of the primary crystalline phase upon heating. Based on the diffraction data, the temperature evolution of structural differences between the alloys is discussed. Thermoplastic forming experiments on a variety of BMGs are performed and the deformation is discussed with respect to their thermophysical properties, leading to a description of the thermoplastic formability and the ideal processing region. These findings are transferred to thermoplastic consolidation experiments on amorphous powder, evaluating this technique for additive manufacturing. Finally, thermoplastic deformation experiments are conducted on the CuTi- and Zr-based alloys with minor additions. Minor additions can be used to significantly improve the thermoplastic formability and hence ease the industrial processability.

Published
2019

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