有限温度下位错环的脱体现象

在FCC单晶铜中构造了滑移面为（111），伯格矢量为b=［112］/6的圆形不完全位错环．采用分子动力学方法模拟了该位错环在0—350 K温度区间内的自收缩过程．模拟结果发现：零温度下，位错不能跨越Peierls-Nabarro势垒运动，迁移速度为0；50　K温度下，螺型和刃型位错具有基本相同的迁移速度；随温度增加，刃型位错具有较大迁移速度；温度较高时，位错核宽度进一步增加；小位错环周围的局部应力，引起4个脱体位错环；脱体位错环在原位错的应力作用下逐渐生长，原位错消失后，在自相 关键词： 单晶铜 位错环 分子动力学 位错源

Separating of dislocation ring at finite temperature

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 resuhs 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.