冲击条件下含纳米空洞的单晶铜的塌缩

利用分子动力学方法研究了单晶铜中不同大小的球形空洞在冲击波下的演化过程.模拟结果表明不同大小空洞的塌缩过程不同.模拟中冲击波由空洞左边扫向空洞右边.在较大尺寸的空洞塌缩过程中会产生系列的位错环.当空洞半径较小时，先在空洞的右侧形成位错环，当空洞半径增大到某一临界大小时，在空洞左右两侧同时产生位错环，当空洞半径较大时，先在空洞左侧形成位错环.当空洞左右两侧的位错环均形成以后，其右侧位错环前端的生长速度大于其左侧的.空洞半径增大，相应的位错环前端的生长速度变化不大.当空洞半径增大时，空洞中心指向位错源的矢量方 关键词： 纳米空洞 位错环 冲击波 塑性变形

Molecular dynamics simulation of shock-induced collapse in single crystal copper with nano-void inclusion

The evolution of preexisting nano-voids of different size in single crystal copper is investigated by means of molecular dynamics (MD) simulations. The results show that void collapse depends upon the size of the void. Numerous dislocation loops emerge for large void and phase transformation takes place in the sample. When the shock wave passes the void from left to right，dislocation loop emerges in the right of the void first for small void. However，loops emerge in the right and the left at the same time when the size of the void increases to a critical size，which is decided by the distribution of the stress near the void. Once dislocation loop emerges and grows，the frontal dislocation loop in the right of void grows faster than that in the left for the same void. When the size of the void increases，the velocity of frontal dislocation loops is essentially unvaried，and the angle between the direction leading from the centre of the void to the initial position of collapse and the direction of impact increases.