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Computational Material Science,
61:54--66
2012
Equipe: Département SI2M : Microstructures et Contraintes |
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Chemistry of materials,
24 (3):2429-2432
2012
DOI: 10.1021/cm301179x
Equipe: Département SI2M : Microstructures et Contraintes |
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Journal of Physics and Chemistry of solids,
73(4):554-558
2012
ISSN: 0022-3697
Resume: Zr1-xWx nanocrystalline films of Zr-W solid solutions and ZrW2 Laves phase were synthesized by magnetron co-sputtering. Large values of the H/E ratio up to 0.09 are observed for grain sizes in the nanometer range along with a hardness above 10 GPa and Young's modulus below 230 GPa. H/E values are correlated with the developed surface of grain boundaries suggesting an elastic deformation mostly handled by the grain boundaries. This is associated to friction coefficients comparable to those of metallic glass surfaces. In contrast to fragile bulk Laves phases, no cracks were detected at the film surface after indentation and scratch test of nanocrystalline ZrW2. The friction coefficient of such films against diamond tip was in the range 0.08-0.15, similarly to metallic glass surfaces. (C) 2011 Elsevier Ltd. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |
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Comptes Rendus Physique,
13(3):257-267
2012
ISSN: 1631-0705
Resume: High energy X-ray diffraction is a powerful tool, able to follow phase transformations during complex thermal or thermo-mechanical treatments. High energy allows one to study volumic specimens of a few mm(3) and get successive data within a few seconds or less. The technique is described with different experimental setups (heating devices, detectors for diverse acquisition times) allowing diverse ranges for heating and cooling rates. Three examples are considered to illustrate the results obtained by using high energy X-ray diffraction. The first one corresponds to a simple diffusive phase transformation during an isothermal thermal path for the alpha-beta transformation in a titanium alloy, highlighting the diffusive character considering the cell parameter evolutions of the parent phase. The second one illustrates the precipitation sequences observed during ageing of a beta-metastable phase in a titanium alloy that was not obtained by TEM. The last example illustrates the phase evolutions during ageing of a martensitic steel showing the complexity of cell parameters evolution and some evolutions of the stress state. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |