Publications: Articles
2012 | |
Articles: | |
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Matériaux et techniques,
100:103-105
2012
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 |
2011 | |
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Solid State Phenomena,
172-174(Part 1):760-765
2011
ISSN: 1012-0394
Resume: In the present study we focus on the precipitation processes during heating and ageing of beta-metastable phase in the near beta Ti-5553 alloy. Transformation processes have been studied using continuous high energy X-Ray Diffraction (XRD) and electrical resistivity for two different states of the beta-metastable phase. Microstructures have been observed by electron microscopy. Different transformation sequences are highlighted depending on both heating rate and chemical composition of the beta-metastable phase. At low temperatures and low heating rates, the hexagonal omega(iso) phase is first formed as generally mentioned in the literature. Increasing the temperature, XRD evidences the formation of an orthorhombic phase (alpha"), which evolves toward the hexagonal pseudo compact alpha phase. For higher heating rates or for richer composition in beta-stabilizing elements of the beta-metastable phase, omega phase may not form and alpha" forms directly and again transforms into alpha phase. A direct transformation from beta-metastable to alpha phase is observed for the highest heating rate. The formation of the metastable omega(iso) and alpha" phases clearly influences the final morphology of alpha. Equipe: Département SI2M : Microstructures et Contraintes |
2010 | |
Articles: | |
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International Journal of Microstructure and Materials Properties,,
5 (1):65-78
2010
Equipe: Département SI2M : Microstructures et Contraintes |
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Nuclear Engineering and Design,
240:1975-1985
2010
Equipe: Département SI2M : Microstructures et Contraintes |
2009 | |
Articles: | |
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Acta Materialia,
57(20):6075-6089
2009
ISSN: 1359-6454
Equipe: Département SI2M : Microstructures et Contraintes |
2007 | |
Articles: | |
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,
448(1-2):135-145
2007
ISSN: 0921-5093
Resume: We have investigated the microstructure evolutions in the Ti17 near beta titanium alloy during heat treatments. The phase transformation has first been studied experimentally by combining X-ray diffraction analysis, electrical resistivity and microscopy observations. From a series of isothermal treatments. a IT diauram has been determined, which takes into account the different morphologies. Then, a Johnson-Mehl-Avrami-Kolmogorov (JMAK) model has been successfully used to describe the phase transformation kinetics during either isothermal or cooling treatments. Finally, the coupling of the JMAK model to the finite element software ZeBuLoN allowed us to investigate the evolution of the spatial distribution of the different morphologies during the cooling of an aircraft engine shaft disk after forging. (c) 2006 Elsevier B.V. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |