Influence of dislocation structure development by cyclic deformation on yield stress in bicrystal models through atomic simulation

Abstract

It is well known that the dislocation structure under cyclic deformation changes according to the magnitude of loading and the number of cycle, but the effect of grain boundaries on the development of dislocation structure is still not well understood. In this study, we perform the molecular dynamics simulations to investigate the effect of grain boundaries and grain sizes on the dislocation structure development in nanoscale bicrystal models under cyclic deformation and also investigate the influence of the dislocation structure formed during the cyclic deformation on the yield phenomenon under tensile deformation. It was confirmed that grain boundaries act as dislocation absorption sites and that the grain size affects the size of the developing dislocation structure. A decrease in dislocation density with cyclic deformation, a decrease in dislocation density with increasing strain amplitude, and a weak correlation between dislocation structure and yield stress after cyclic deformation are obtained.