Separating of dislocation ring at finite temperature

Abstract

We constructed a partial dislocation ring with Burgers vector b=［112］/6 in the glide plane （111） of copper crystal, and studied its self-contraction process in the temperature range, from 0 to 350 K by using molecular dynamics simulations. The results reveal that, at zero temperature the dislocation ring cannot pass the Peierls-Ｎabarro potential barrier, so its migrating velocity is zero; below 50 K, the screw part and the edge part of the dislocation have nearly the same migrating velocity. With the increasing of temperature, the edge dislocation migrates more quickly than the screw dislocation. At a higher temperature, the dislocation core becomes wider, consequently, it may contain more complex internal structures and becomes easier for separating. At the same time, local stress gradient within the mixed dislocation zone becomes steeper and results in the generation of four partial dislocation rings. The four new dislocation rings first grow with time under the influence of original dislocation ring. When the original ring finally disappears, the newly created rings begin to shrink and finally disappear. This is a new dislocation source, different from the Frank-Read，L or double cross-slip type.