Strongly correlated breeding of high-speed dislocations

QJ Li and J Li and ZW Shan and E Ma, ACTA MATERIALIA, 119, 229-241 (2016).

DOI: 10.1016/j.actamat.2016.07.053

Under very high stresses, dislocations can be accelerated to approach the speed of shear wave over a distance as short as 10(1) nm. Our atomistic simulations demonstrate that dislocations with such high speeds often react in counter-intuitive manners that are beyond textbook descriptions of conventional dislocation behavior. A high-speed dislocation can "rebound" when hitting a free surface rather than simply annihilate. When two high-speed dislocations collide, they can "penetrate" through each other. An individual dislocation can even spontaneously generate multiple dislocations via self-dissociation. These anomalous mechanisms lead to rapid proliferation of dislocations that are strongly correlated both spatially and temporally, and as such may play a role in high-stress and high-strain-rate plastic deformation; a potentially related case is nanoscale pristine single crystals, which often yield via a large strain burst at ultrahigh stresses. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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