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Publications: Articles

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References

2012

Articles:

Brunetti, G., Settefrati, A., Hazotte, A., Denis, S., Fundenberger, J. -J., Tidu, A. and Bouzy, E.
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

Horwat, D., Dehmas, M., GUTIERREZ, A., Pierson, J.F., Anders, A., SOLDERA, F. and Endrino, J.L.
Chemistry of materials, 24 (3):2429-2432
2012

Equipe: Département SI2M : Microstructures et Contraintes

Horwat, D., JIMENEZ-PIQUE, E., Pierson, J. F., Migot, S., Dehmas, M. and Anglada, M.
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

2011

Articles:

Hell, Jean-Christophe, Dehmas, Moukrane, Allain, Sebastien, Prado, Juscelino Mendes, Hazotte, Alain and Chateau, Jean-Philippe
ISIJ International, 51(10):1724-1732
2011
ISSN: 0915-1559

Resume: We elaborated two carbide-free bainitic steels with different microstructures through specific alloy design and austempering process. Microstructural characterizations were performed by means of EBSD analysis and in-situ high energy synchrotron diffraction in order to evaluate the phase fractions and the carbon content in the retained austenite, as well as the microtextures. These microstructural features were correlated to the tensile properties. Both steels exhibited an excellent compromise between high strength (above 1 250 MPa), good ductility (uniform elongation up to 14%) and high fracture strain (reduction of area up to 46%). The volume fraction of MA blocks (blocks of retained austenite partially transformed into fresh martensite during the final cooling at room temperature) was a key relevant parameter that strongly influenced the work-hardening at the expense of the damaging processes at high strain.

Equipe: Département SI2M : Microstructures et Contraintes

2009

Articles:

Horwat, D., Dehmas, M., Aubry, E., Zollinger, J., Migot, S. and Pierson, J. F.
Intermetallics, 17(6):421-426
2009
ISSN: 0966-9795

Resume: WxZr1-x thin films were deposited at room temperature on glass substrates by co-sputtering tungsten and zirconium targets in argon. The composition was found in the range 0 <= x <= 0.81. The grain size deduced from X-ray diffraction analysis ranged from 1.3 nm to 16 nm depending on the composition. The events in the resistivity, optical reflectivity and thickness evolutions were correlated with the X-ray diffraction analysis. Depending on the composition, the local organization can be attributed to a nanocrystalline solid solution of W in Zr, to a nanocomposite structure involving ZrW2 nanograins embedded in an amorphous matrix. to ZrW2 Laves phase nanograins and to a nanocrystalline solid solution of Zr in W. For 0 < x <= 0.72, the equivalent grain size is very small (less than 2 nm) and the evolution of the resistivity can be fitted by the estimated volume of the material perturbed by the grain boundaries. (C) 2008 Elsevier Ltd. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

Hutchinson, C.R., Loo, P.T., Bastow, T.J., Hill, A.J. and da Costa Teixeira, J.
Acta Materialia, 57(19):5645-5653
2009
ISSN: 1359-6454

Equipe: Département SI2M : Microstructures et Contraintes

da Costa Teixeira, J., Bourgeois, L., Sinclair, C.W. and Hutchinson, C.R.
Acta Materialia, 57(20):6075-6089
2009
ISSN: 1359-6454

Equipe: Département SI2M : Microstructures et Contraintes

2008

Articles:

Morniroli, J. P., Houdellier, F., Roucau, C., Puiggali, J., Gesti, S. and Redjaïmia, A.
Ultramicroscopy, 108 (2)(2):100-115
2008
ISSN: 0304-3991

Resume: By combining the large-angle convergent-beam electron diffraction (LACBED) configuration together with a microscope equipped with a C., corrector it is possible to obtain good quality spot patterns in image mode and not in diffraction mode as it is usually the case. These patterns have two main advantages with respect to the conventional selected-area electron diffraction (SAED) or microdiffraction patterns. They display a much larger number of reflections and the diffracted intensity is the integrated intensity. These patterns have strong similarities with the electron precession patterns and they can be used for various applications like the identification of the possible space groups of a crystal from observations of the Lane zones or the ab-initio structure identifications. Since this is a defocused method, another important application concerns the analysis of electron beam-sensitive materials. Successful applications to polymers are given in the present paper to prove the validity of this method with regards to these materials. (c) 2007 Elsevier B.V. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

Teixeira, Julien Da Costa, Appolaire, Benoit, Aeby-Gautier, Elisabeth, Denis, Sabine and Hericher, Ludovic
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:

Hutchinson, C.R., Goune, M. and Redjaïmia, A.
Acta Materialia, 55(1):213-223
2007
ISSN: 1359-6454

Resume: A physically based process model for the room temperature yield strength of an age-hardenable alloy subject to selected monotonic non-isothermal heat treatment schedules is developed and used to examine the possible efficiencies in processing and enhancements in strength that may be realistically achieved. `Processing Maps' are generated which illustrate both the yield strengths achievable and the processing routes necessary to achieve them, as well as estimates of the energy consumed in the thermal treatment. A Fe-2Cu (wt.%) alloy is used as an example and the results of physical experiments are compared with the model predictions. For the conditions examined, enhancements in yield strength of similar to 8% above those achievable in comparable isothermal treatments are illustrated with 65% of the energy input. Alternatively, similar yield strengths to those from comparable isothermal treatment are shown to be achievable with similar to 35% of the energy input. The physical origins of the observed effects and the potential implications of coupled process-property optimization are considered. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Equipe: Département SI2M : Microstructures et Contraintes

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