Dislocation mobility in two-dimensional Lennard-Jones material

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:309

Article; Proceedings Paper

Bailey, NP ; Sethna, JP ; Myers, CR

关键词: dislocation mobility;    Lennard-Jones;    energy barriers;    nudged elastic band;   

DOI  :  10.1016/S0921-5093(00)01715-9

来源: Elsevier

【 摘 要 】

In seeking to understand at a microscopic level the response of dislocations to stress, we have undertaken to study as completely as possible the simplest case: a single dislocation in a two-dimensional crystal. The intention is that results from this study will be used as input parameters in larger length scale simulations involving many defects. We present atomistic simulations of defect motion in a two-dimensional material consisting of atoms interacting through a modified Lennard-Jones potential. We focus on the regime where the shear stress is smaller than its critical value, where there is a finite energy barrier for the dislocation to hop one lattice spacing. In this regime motion of the dislocation will occur as single hops through thermal activation over the barrier. Accurate knowledge of the barrier height is crucial for obtaining rates of such processes. We have calculated the energy barrier as a function of two components of the stress tenser in a small system, and have obtained good fits to a functional form with only a few adjustable parameters. We examine prefactors, finite temperature and dynamics. (C) 2001 Elsevier Science B.V. All rights reserved.

【 授权许可】

Free