2014 | |
Articles: | |
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Acta Materialia,
80:118--131
2014
ISSN: 1359-6454
Equipe: Département SI2M : Microstructures et Contraintes |
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Investigation of the growth kinetics of gamma -> alpha in Fe-C-X alloys with a thick interface model
Computational Materials Science,
82:151-158
2014
Equipe: Département SI2M : Microstructures et Contraintes |
2013 | |
Articles: | |
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Acta Materialia,
61:3758-3768
2013
Equipe: Département SI2M : Microstructures et Contraintes |
2012 | |
Articles: | |
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Computational Material Science,
61:54--66
2012
Equipe: Département SI2M : Microstructures et Contraintes |
2011 | |
Articles: | |
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Solid State Phenomena,
172-174(Part 1):1214-1219
2011
ISSN: 1012-0394
Resume: We have adapted the Quickhull algorithm with the general dimension Beneath-Beyond algorithm [6] for computing the convex hull of the Gibbs energy hypersurface of multicomponent two-phase alloys. We illustrate the salient features of our method with calculations of isothermal ferrite-austenite equilibria in Fe-C-Cr. Finally, successive equilibrium calculations in a Fe-C-Cr-Mo steel over a large temperature range show the benefit of computing the convex hull before performing the conventional Newton-Raphson search. Equipe: Département SI2M : Microstructures et Contraintes |
2010 | |
Articles: | |
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Philisophical magazine,
90(1-4):461-483
2010
ISSN: 1478-6435
Resume: We propose a description of incoherent and semi-coherent interfaces within the framework of diffuse interface modelling: accounting for the discontinuity of tangential displacements is an issue addressed by introducing a new field, called the incoherency field, located in the diffuse interface and able to release the shear stresses tangential to the interface. After having demonstrated the ability of the model to recover trends obtained by sharp interface models of sliding interfaces, the process of loss of coherency is investigated by assuming a local process which would result from the competition between the shear stress release at the interface and the interfacial energy increase. Equipe: Département SI2M : Microstructures et Contraintes |
2008 | |
Articles: | |
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MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING,
476(1-2):60-68
2008
ISSN: 0921-5093
Resume: The beta(BCC) -> alpha(HCP) + beta(BCC) phase transformation kinetics of the beta-metastable titanium alloy Ti17 was studied by in situ high energy X-ray diffraction (XRD) and electrical resistivity. The use of synchrotron radiation (E = 89.12 keV, lambda = 0.01402 nm) allowed to characterize specimens 6 mm in diameter, limiting thus oxidation effects. The alpha + beta -> beta phase transformation kinetics was characterized during continuous heating up to the P temperature range. The beta -> alpha + beta transformation was studied in isothermal conditions (dwell at 708 degrees C or 750 degrees C) and during continuous cooling (cooling rates of 0.05 degrees C/s, 0.1 degrees C/s and 0.61 degrees C/s). The evolutions of the phase fractions are analyzed and compared to kinetics measured by electrical resistivity, showing a good correlation between both methods. In addition, the evolutions of the cell parameters of each phase obtained from XRD patterns are analyzed in regard of the transformation kinetics. (C) 2007 Elsevier B.V. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |
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COMPUTATIONAL MATERIALS SCIENCE,
42(2):266-280
2008
ISSN: 0927-0256
Resume: A complete modeling of the phase transformation during the cooling following the forging has been carried out for near-beta titanium alloys. To that aim, we have improved a model predicting the influence of the deformation of the beta phase on the alpha phase precipitation during isothermal treatments, by extending its range of application to the case of cooling treatments. In particular, the precipitation of the intragranular morphology alpha(WI) has been introduced. We have proceeded step by step: calculations of heat treatments without any previous forging have first been performed. Then, the influence of the initial beta grain size have been studied. Finally, the influence of a previous deformation coming from the forging has been investigated. At each step, the calculations have been compared to some experiments, showing an good overall agreement. (C) 2007 Elsevier B.V. All rights reserved. Equipe: Département SI2M : Microstructures et Contraintes |
2007 | |
Articles: | |
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Journal of Materials,
59(1):54-58
2007
ISSN: 1047-4838
Resume: The prediction of microstructure during processing needs to characterize the phase transformation occurring during the thermal treatments and their kinetics. In-situ high-energy synchrotron x-ray diffraction experiments performed during temperature variations allow the characterization of the phase evolution. For some transformation conditions, the continuous recording of diffraction diagrams evidences clearly intermediate phases. The quantitative analysis of the diffraction diagrams gives the transformation kinetics of each phase as well as their cell parameters. Transformation kinetics obtained by this method are compared to results obtained by electrical resistivity. Equipe: Département SI2M : Département SI2M : Microstructures et Contraintes |
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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 |