Publications: Articles
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Micron,
43(2-3):396-406
2012
ISSN: 0968-4328
Resume: In single-crystal nickel-based superalloys, the lattice mismatch associated with interface coherency between gamma matrix and gamma' precipitates has a strong influence on mechanical properties. The unconstrained lattice misfit in a single-crystal of the MC2 nickel-based superalloy is determined using convergent beam electron diffraction measurements and finite element calculations. The apparent lattice parameters of both constrained phases are obtained in thin foils, using a new multi-pattern approach, which allows for unambiguous determination of all the lattice parameters considering the real symmetry of the strained crystals. Finite element calculations are used to establish relations between the constrained and unconstrained lattice parameters, with the stress relaxation resulting from the thin foil geometry taken into account. (C) 2011 Elsevier Ltd. All rights reserved. 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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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 |