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Publications: Articles

Toutes :: 2007, 2008, 2011, 2012, ... , 2014
Tous :: A, B, C, D, E, F, G, H, I, J, K, L, M, N, P, R, S, T, V, W, X, Y, Z 
Tous :: Gautier, Geandier, Gelfi, Germain, ... , GUTIERREZ 
References par page: Mots clefs Voir les resumes


Berveiller, S., Malard, B., Wright, J., Patoor, E. and Geandier, G.
Acta Materialia, 59(9):3636-3645
ISSN: 1359-6454

Resume: Two synchrotron diffraction techniques, three-dimensional X-ray diffraction and Laue microdiffraction, are applied to studying the deformation behaviour of individual grains embedded in a Cu(74)Al(23)Be(3) superelastic shape memory alloy. The average lattice rotation and the intragranular heterogeneity of orientations are measured during in situ tensile tests at room temperature for four grains of mean size similar to 1 mm. During mechanical loading, all four grains rotate and the mean rotation angle increases with austenite deformation. As the martensitic transformation occurs, the rotation becomes more pronounced, and the grain orientation splits into several sub-domains: the austenite orientation varies on both sides of the martensite variant. The mean disorientation is similar to 1 degrees. Upon unloading, the sub-domains collapse and reverse rotation is observed. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

Borgese, L., Bontempi, E., Gelfi, M., Depero, L. E., Goudeau, P., Geandier, G. and Thiaudière, D.
Acta Materialia, 59(7):2891-2900
ISSN: 1359-6454

Resume: Amorphous TiO2 thin films were deposited by means of atomic layer deposition on Kapton substrates and then crystallized ex situ by annealing at 300 degrees C to obtain the anatase phase. The morphology, structure and microstructure of films treated for 12, 24, 72 and 90 h were investigated. The local Ti coordination changes were studied by X-ray near-edge structure (XANES). On the basis of X-ray diffraction residual stress calculations, the elastic anisotropy of the films is experimentally determined for the first time (A*(comp) = 0.07, A*(shear) = 0.03). The film macro-strains increased with the time of treatment, while the micro-strains decreased. This effect may be correlated with the incipient anatase-to-rutile transformation as suggested by the changes observed in the XANES pattern of the film treated for 90 h. However, the contribution of the substrate cannot be excluded. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

Settefrati, A., Aeby-Gautier, E., Dehmas, M., Geandier, G., Appolaire, B., Audion, S. and Delfosse, J.
Solid State Phenomena, 172-174(Part 1):760-765
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

Faurie, D., Renault, P. -O., Geandier, G. and Le Bourhis, E.
Thin Solid Films, 520(5):1603-1607
ISSN: 0040-6090

Resume: Synchrotron x-ray radiation was used for in situ strain measurements in gold films on polyimide substrate during uniaxial deformation tests. We have used an area detector that allows inspecting multiple directions in the polycrystalline thin film without serial sectioning during straining. We show in this paper the configuration used and the attainable orientations on a pole figure for which the x-ray strains are measured. Moreover, we show the effect on the x-ray strains of the onset on plasticity, which was not detected by optical (macroscopic) strain measurement. (C) 2011 Elsevier B.V. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

Mourot, Mickael, Courleux, Alice, Dehmas, Moukrane, Gautier, Elisabeth, Geandier, Guillaume, Dezellus, Olivier, Claude Viala, Jean, Martin, Olivier, Karnatak, Nikhil and Danoix, Frederic
Solid State Phenomena, 172-174:747-752

Equipe: Département SI2M : Microstructures et Contraintes

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