@ARTICLE{10985-9880,
	journal = {Journal of the Mechanics and Physics of Solids},
	volume = {83},
	pages = {199-220},
	year = {2015},
	author = {DETREZ, Fabrice and CASTELNAU, Olivier and CORDIER, Patrick and MERKEL, Sébastien and RATERRON, Paul},
	abstract = {Polycrystalline aggregates lacking four independent systems for the glide of dislocations can deform in a purely viscoplastic regime only if additional deformation mechanisms (such as grain boundary sliding and diffusion) are activated. We introduce an implementation of the self-consistent scheme in which this additional physical mechanism, considered as a stress relaxation mechanism, is represented by a nonlinear isotropic viscoplastic potential. Several nonlinear extensions of the self-consistent scheme, including the second-order method of Ponte-Castañeda, are used to provide an estimate of the effective viscoplastic behavior of such polycrystals. The implementation of the method includes an approximation of the isotropic potential to ensure convergence of the attractive fixed-point numerical algorithm. The method is then applied to olivine polycrystals, the main constituent of the Earth's upper mantle. Due to the extreme local anisotropy of the local constitutive behavior and the subsequent intraphase stress and strain-rate field heterogeneities, the second-order method is the only extension providing qualitative and quantitative accurate results. The effective viscosity is strongly dependent on the strength of the relaxation mechanism. For olivine, a linear viscous relaxation (e.g. diffusion) could be relevant; in that case, the polycrystal stress sensitivity is reduced compared to that of dislocation glide, and the most active slip system is not necessarily the one with the smallest reference stress due to stress concentrations. This study reveals the significant importance of the strength and stress sensitivity of the additional relaxation mechanism for the rheology and lattice preferred orientation in such highly anisotropic polycrystalline aggregates.},
	issn = {0022-5096},
	edition = {Post-print},
	title = {Effective viscoplastic behavior of polycrystalline aggregates lacking four independent slip systems inferred from homogenization methods; application to olivine},
	publisher = {Elsevier},
	url = {10.1016/j.jmps.2015.05.022}
}

@ARTICLE{10985-15088,
	journal = {Journal of Applied Crystallography},
	volume = {48},
	pages = {1805-1817},
	year = {2015},
	author = {ZHANG, F. G and CASTELNAU, Olivier and BORNERT, Michel and MARIJON, Jean-Baptiste and PLANCHER, Emeric and PETIT, Johann},
	abstract = {A new method of determining the deviatoric elastic strain and lattice orientation from Laue microdiffraction images is presented. Standard data treatment methods can suffer from the difficulty of precisely pinpointing the positions of diffraction peaks on two-dimensional Laue images. In a previous article, digital image correlation (DIC) was introduced for the treatment of Laue images, leading to the so-called Laue-DIC method. This performed better than the standard method in terms of the deviatoric elastic strain increment and relative rotation from one lattice to another, particularly when the shape of the Laue spots departs from regular ellipsoids. The present work intends to push forward the Laue-DIC method, aiming to determine the deviatoric elastic strain and lattice orientation, as well as the calibration parameters. The performance of this new method, named enhanced Laue-DIC, is assessed by modeling the spot displacements and accounting for random fluctuations relevant for typical experimental conditions. When the enhanced Laue-DIC method is applied to the case of an in situ deformed Si crystal, the obtained standard deviation of local stress is of the order of 1-2 MPa, while the calibration parameters are optimized to high accuracy.},
	issn = {0021-8898},
	edition = {Post-print},
	title = {Determination of deviatoric elastic strain and lattice orientation by applying digital image correlation to Laue microdiffraction images: The enhanced Laue-DIC method},
	publisher = {International Union of Crystallography},
	url = {10.1107/S1600576715018397}
}

@ARTICLE{10985-10860,
	journal = {Superlattices and Microstructures},
	volume = {88},
	pages = {551-560},
	year = {2015},
	author = {FAURIE, D and DJEMIA, P and CASTELNAU, Olivier and BRENNER, Renald and BELLIARD, L and GOUDEAU, P and RENAULT, P.-O and LE BOURHIS, E},
	abstract = {We show in this paper by using a two-scale transition model that the elastic anisotropy of a thin film specimen can be tuned by appropriate stacking design. The anisotropic behaviour is illustrated for two monophase thin films, namely W which is perfectly elastically isotropic and Au which is strongly elastically anisotropic, and for a nanometric W/Au multilayers. The experimental measurements show that the model capture the elastic anisotropy rather well even for a nanometric multilayer stacking (period of 12 nm) and that the elastic anisotropy of W/Au multilayer is more pronounced than the ones of the two components for a fraction of 50%. This enhanced anisotropy is discussed in view of the multilayer microstructure},
	issn = {0749-6036},
	edition = {Post-print},
	title = {Peculiar effective elastic anisotropy of nanometric multilayers studied by surface Brillouin scattering},
	publisher = {Elsevier},
	url = {10.1016/j.spmi.2015.10.015}
}

@ARTICLE{10985-10917,
	journal = {Matériaux \& Techniques},
	volume = {103},
	pages = {9},
	year = {2015},
	author = {GU, T and HERVE-LUANCO, E and PROUDHON, H and THILLY, L and DUBOIS, J.-B. and LECOUTURIER, F and CASTELNAU, Olivier and FOREST, S},
	abstract = {Les fils composites nanostructurés et architecturés cuivre-niobium, qui sont de bons candidats pour la génération de champs magnétiques intenses, allient une limite d’élasticité élevée et une excellente conductivité électrique. Ils sont élaborés par co-déformation d’un assemblage composite Cu-Nb. La microstructure, multi-échelle, est formée de 853 motifs élémentaires de Cu-Nb de taille caractéristique nanométrique. Afin d’étudier le lien entre la conductivité électrique effective et la microstructure, deux méthodes d’homogénéisation sont appliquées : l’une, en champs moyens (modèle auto-cohérent généralisé), dans laquelle une microstructure formée de motifs co-cylindriques répartis aléatoirement est considérée, et l’autre, en champs complets (éléments finis), dans laquelle l’aspect périodique de la microstructure expérimentale est pris en compte. Les effets de la taille des constituants élémentaires (nm), de la température, ainsi que de la densité de dislocations, sur la conductivité locale sont considérés. Le caractère multi-échelle du matériau est pris en compte grâce à un processus itératif. Les conductivités effectives longitudinale et transversale obtenues avec les deux méthodes sont en excellent accord, montrant un moindre effet de la distribution des fibres sur ces propriétés. Ces résultats reproduisent également les données expérimentales disponibles.},
	issn = {0032-6895},
	edition = {Post-print},
	title = {Modélisation multi-échelle du comportement électrique de nano-composites Cu-Nb},
	publisher = {EDP Sciences},
	url = {10.1051/mattech/2015033}
}

@ARTICLE{10985-9890,
	journal = {Journal of Synchrotron Radiation},
	volume = {22},
	pages = {980-994.},
	year = {2015},
	author = {PETIT, J and CASTELNAU, Olivier and BORNERT, Michel and ZHANG, F. G. and HOFMANN, F and KORSUNSKY, A. M and FAURIE, D and LE BOURLOT, C and MICHA, Jean-Sébastien and ROBACH, O and ULRICH, O},
	abstract = {A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10-5.},
	issn = {0909-0495},
	edition = {Post-print},
	title = {Laue-DIC : a new method for improved stress field measurements at the micrometer scale},
	publisher = {International Union of Crystallography},
	url = {10.1107/S1600577515005780}
}

@ARTICLE{10985-10415,
	journal = {Geophysical Journal International},
	volume = {203},
	pages = {334-350},
	year = {2015},
	author = {GOULDING, Neil J. and RIBE, Neil M. and CASTELNAU, Olivier and WALKER, Andrew M.},
	abstract = {Progressive deformation of upper mantle rocks via dislocation creep causes their constituent crystals to take on a non-random orientation distribution (crystallographic preferred orientation or CPO) whose observable signatures include shear-wave splitting and azimuthal dependence of surface wave speeds. Comparison of these signatures with mantle flow models thus allows mantle dynamics to be unraveled on global and regional scales. However, existing self-consistent models of CPO evolution are computationally expensive when used with 3-D and/or time-dependent convection models. Here we propose a new method, called ANPAR, which is based on an analytical parametrization of the crystallographic spin predicted by the second-order (SO) self-consistent theory. Our parametrization runs ≈2–6 × 104 times faster than the SO model and fits its predictions for CPO and crystallographic spin with a variance reduction >99 per cent. We illustrate the ANPAR model predictions for the deformation of olivine with three dominant slip systems, (010)[100], (001)[100] and (010)[001], for three uniform deformations (uniaxial compression, pure shear and simple shear) and for a corner-flow model of a spreading mid-ocean ridge.},
	issn = {0956-540X},
	edition = {Post-print},
	title = {Analytical parametrization of self-consistent polycrystal mechanics: Fast calculation of upper mantle anisotropy},
	publisher = {Oxford University Press (OUP)},
	url = {10.1093/gji/ggv304}
}

@ARTICLE{10985-10166,
	journal = {Materials Characterization},
	volume = {104},
	pages = {31-41},
	year = {2015},
	author = {WAUTHIER-MONNIN, Aurélie and CHAUVEAU, T and CASTELNAU, Olivier and RÉGLÉ, H and BACROIX, Brigitte},
	abstract = {During the deformation of low carbon steel by cold-rolling, dislocations are created and stored in grains depending on local crystallographic orientation, deformation, and deformation gradient. Orientation dependent dislocation densities have been estimated from the broadening of X-ray diffraction lines measured on a synchrotron beamline. Different cold-rolling levels (from 30% to 95% thickness reduction) have been considered. It is shown that the present measurements are consistent with the hypothesis of the sole consideration of screw dislocations for the analysis of the data. The presented evolutions show that the dislocation density first increases within the α fiber (={hkl}<110>) and then within the γ fiber (={111}<uvw>). A comparison with EBSD measurements is done and confirms that the storage of dislocations during the deformation process is orientation dependent and that this dependence is correlated to the cold-rolling level. If we assume that this dislocation density acts as a driving force during recrystallization, these observations can explain the fact that the recrystallization mechanisms are generally different after moderate or large strains.},
	issn = {1044-5803},
	edition = {Post-print},
	title = {The evolution with strain of the stored energy in different texture components of cold-rolled if steel revealed by high resolution X-ray diffraction},
	publisher = {Elsevier},
	url = {10.1016/j.matchar.2015.04.005}
}