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Nanostructuration d'un composite Cu-Fe par déformation intense : vers un mélange forcé à l'échelle atomique

Abstract : Materials processed by severe plastic deformation (SPD), usually exhibit unusual mechanical properties because of their small grain size and the high density of dislocations. However these defects may give rise to phase transformations. The aim of this work was to obtain non equilibrium solid solution by high pressure torsion (HPT) in the Cu-Fe model system and to identify mechanisms involved in this phase transformation. The initial material was a filamentary nanocomposite fcc-Cu/bcc-Fe. Slices of this composite were processed by HPT for a full range of stain. The material has been investigated with XRD, Mössbauer spectroscopy, TEM and atom probe tomography. Initial bcc-Fe filaments are reduced by HPT until a critical size of about 5 nm. Then the solid solution formation occurs by diffusion in fcc-Cu. This phase is made of equiaxed grains of about 50 nm. Nor dislocations nor interfaces shearing could explained data whereas diffusion profiles give the evidence that enhanced diffusion rate can be attributed to excess vacancies.
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Submitted on : Tuesday, December 6, 2011 - 11:33:58 AM
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  • HAL Id : tel-00648688, version 1

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Xavier Quelennec. Nanostructuration d'un composite Cu-Fe par déformation intense : vers un mélange forcé à l'échelle atomique. Science des matériaux [cond-mat.mtrl-sci]. Université de Rouen, 2008. Français. ⟨tel-00648688⟩

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