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Statistics of dislocations at low temperature in pure metals with body centered cubic symmetry

Abstract : In situ straining tests in high purity α-Fe thin-foils at low temperatures have demonstrated that crystalline defects, called dislocations, have a jerky type of motion made of intermittent long jumps of several nanometers. Such an observation is in conflict with the standard Peierls mechanism for plastic deformation in bcc crystals, where the screw dislocation jumps are limited by inter-reticular distances, i.e. of a few Angstroms. Employing atomic-scale simulations, we show that although the short jumps are initially more favorable, their realization requires the propagation of a kinked profile along the dislocation line which yields coherent atomic vibrations acting as traveling thermal spikes. Such local heat bursts favor the thermally assisted nucleation of new kinks in the wake of primary ones. The accumulation of new kinks leads to long dislocation jumps like those observed experimentally. Our study constitutes an important step toward predictive atomic-scale theory for materials deformation.
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  • HAL Id : tel-02100533, version 1

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Anshuman Choudhury. Statistics of dislocations at low temperature in pure metals with body centered cubic symmetry. General Physics [physics.gen-ph]. Université Paris-Saclay, 2018. English. ⟨NNT : 2018SACLS569⟩. ⟨tel-02100533⟩

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