Claude Fressengeas

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We present high resolution observations of microstructure and texture evolution during dynamic recrystallization (DRX) of ice polycrystals deformed in the laboratory at high temperature (≈0.98Tm). Ice possesses a significant viscoplastic anisotropy that induces strong strain heterogeneities, which result in an early occurrence of DRX mechanisms. It is(More)
We report a crossover from chaotic to self-organized critical dynamics in the Portevin-Le Chatelier effect in single crystals of Cu-10% Al in tension as a function of the applied strain rate. For low and intermediate strain rates, we provide an unambiguous support for the existence of chaotic stress drops by showing the existence of a finite correlation(More)
Mantle flow involves large strains of polymineral aggregates. The strongly anisotropic plastic response of each individual grain in the aggregate results from the interactions between neighbouring grains and the continuity of material displacement across the grain boundaries. Orthorhombic olivine, which is the dominant mineral phase of the Earth's upper(More)
The collective behavior of dislocations in jerky flow is studied in Al-Mg polycrystalline samples subjected to constant strain rate tests. Complementary dynamical, statistical, and multifractal analyses are carried out on the stress-time series recorded during jerky flow to characterize the distinct spatiotemporal dynamical regimes. It is shown that the(More)
The continuum mechanics of line defects representing singularities due to terminating discontinuities of the elastic displacement and its gradient field is developed. The development is intended for application to coupled phase transformation, grain boundary, and plasticity-related phenomena at the level of individual line defects and domain walls. The(More)
Single crystals of ice subjected to primary creep in torsion exhibit a softening behavior: the plastic strain rate increases with time. In a cylindrical sample, the size of the radius affects this response. The smaller the radius of the sample becomes while keeping constant the average shear stress across a section, the softer the response. The(More)
Instabilities of plastic flow in alloys and the associated deformation patterns are currently attracting a lot of attention. We comment on a recent investigation by Franklin et al. [Phys. Rev. E 62, 8195 (2000)] on one such type of instability, the Portevin-Le Chatelier effect, attempting to clarify a few points about the instability mechanism as well as(More)
Thermomechanical coupling and thermal softening are the critical material properties in the development of adiabatic shear bands. Besides the material effects, the sample geometrical imperfections and the material structural defects are regarded as providing the sites for the onset of the localization process. In this paper, the influence of the shape and(More)
S. I. Bozhko,1,2 V. Taupin,3 M. Lebyodkin,3 C. Fressengeas,3 E. A. Levchenko,4 K. Radikan,2 O. Lübben,2 V. N. Semenov,1 and I. V. Shvets2 1Institute of Solid State Physics, Russian Academy of Science, 142432 Chernogolovka, Moscow District, Russia 2Centre for Research on Adaptative Nanostructures and Nanodevices (CRANN), School of Physics, Trinity College(More)