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103 results on '"Bolle B"'

1. Stability and elastic properties of Ti-alloys for biomedical application designed with electronic parameters

Author

Wary M., Castany P., Laille D., Prima F., Patoor E., Gloriant T., Bolle B., Eberhardt A., Elmay W., and Laheurte P.

Subjects
Physics, QC1-999
Abstract

Titanium alloys are receiving a big attention for biomedical applications. Recently, b type titanium alloys composed of non-toxic elements are being developed for these applications. The aim of this paper is to study mechanical properties and deformation mechanisms of three beta titanium alloys designed with similar values of Bo-Md and e/a ratio. The contribution of electronic approach to predict beta phase stability is also discussed. The microstructural analysis and the mechanical characterization are carried out for different metallurgical states (cold working, solution treatment and aging treatment). Effects of aging treatment at low temperature is also investigated, showing that isothermal holding at 400°C for 0,6 ks after cold working improves the mechanical properties of alloys.

Published
2010
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36. Surface Integrity In High Speed Machining Of Alloy.

Author

Youtsos, A.G., Velásquez, J.D. Puerta, Bolle, B., Chevrier, P., and Tidu, A.

Abstract

Surface integrity of commercial Ti-6wt.%Al-4wt.%V alloy after high speed machining has been investigated. Scanning electron microscopy reveals highly deformed grains in the obtained surface, turned in the direction of the cutting tool passage. X-ray diffraction confirms the intense deformation of the machined surface and shows a crystallographic texture modification. The metallurgical observations do not reveal any phase transformation and no evidence of formation of a white layerhas been noticed. A preliminary study of the residual stress reveals a strong influence of machining parameters on the residual stress in obtained surface. [ABSTRACT FROM AUTHOR]

Published
2006
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44. Texture and Microstructure at the Surface of an AISI D2 Steel Treated by High Current Pulsed Electron Beam.

Author

Zhou, J. X., Grosdidier, T., Bolle, B., Zhang, K. M., and Dong, C.

Subjects
METALLIC surfaces, CRYSTAL texture, STEEL metallurgy, ELECTRON beams, STEEL analysis, EFFECT of temperature on metals, X-ray diffraction, MICROSTRUCTURE, SCANNING electron microscopy, ELECTRON backscattering
Abstract

Surface modifications were investigated for an AISI D2 steel after 25 pulses of high current pulsed electron beam (HCPEB) treatment. In particular, X-ray diffraction (XRD) was used to determine the thickness, nature of phase, and texture in the top surface melted layer. The mechanisms responsible for the structure and texture evolutions were further asserted by scanning electron microscopy (SEM) and electron backscattering diffraction (EBSD) results. Under the action of the beam, the large carbides present in the steel were melted and dissolved so that the top surface rapidly solidified as a 3-μm-thick layer of ultra-fine-grained metastable austenite without any martensite formation. The growth of the γ phase led to an unusual <100> + <110> fiber solidification texture. In addition, Σ3-twin boundaries were observed to bridge, most often, near < 110> domains. These features, observed here in a Fe supersaturated and highly undercooled melt, are discussed in light of recent findings on atypical growth in directionally solidified Al-based alloys.[sup40-23] Comparatively, the α phase present in the heat affected zone remained randomly oriented. [ABSTRACT FROM AUTHOR]

Published
2007
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47. Grain Refinement and Hardening Induced by Heavy Deformation Using Low Energy High Current Pulsed Electron Beam Surface Treatment

Author

Grosdidier, Thierry, Samih, Y., Allain-Bonasso, Nathalie, Bolle, B., Zou, Z.X., Quin, Y., Hao, Sheng Zhi, and Dong, Chuang

Abstract

The low energy high current pulse electron beam (LEHCPEB) irradiation induces ultra fast dynamic temperature fields in the surface of the material to which is associated dynamic stress fields that causes intense deformation at the material surface and sub-surface. Improved surface properties (hardness, corrosion resistance) can be obtained using the LEHCPEB treatment. Under the “Melting” mode, the top surface (few µm) which is melted and rapidly solidified (107 K/s), can solidify has nano-domains formed from the highly under-cooled melt. The thermal stress wave that propagates in the sub-surface imposes strain hardening and grain size refinement. This induces a sub-surface hardening that can extent over about 100 µm. The use of the “Heating” mode is less conventional. This mode can promote grain size refinement, hardening as well as texture modification without modification of the sample geometry.

Published
2010
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48. Thermal Effects of Continuous Laser Treatment on Ti-6 Al(wt%)-4V(wt%) Titanium Alloy

Author

Puerta Velásquez, J.D., Lavisse, L., Kneip, J.C., Andrzejewski, H., Chevrier, P., Bolle, B., Tidu, Albert, and Matteï, S.

Abstract

A titanium alloy Ti-6 Al(wt%)-4V(wt%) was treated in air by Nd:YAG laser radiation (wavelength of 1.064 %m) in continuous mode. Targets were irradiated globally with different levels of energy (accumulated fluence) at constant power. Different focal lengths and beam displacement velocities were used. Cross section microstructural observations were carried out by scanning electron microscopy. Backscattered electron imaging reveals microstructural modifications in samples. A structural phase transformation of beta (bcc) to alpha prime (hcp) phase was observed. The depth of the transformed zone observed by phase transformation is dependent on the treatment parameters. Conformity between microstructural observations and the treatment parameters is discussed with reference to thermal simulations.

Published
2008
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