TiAl中空位团的稳定构形及其对附近空位迁移行为的影响

The Stable Configurations of Vacancy Clusters and Their Effect on Neighboring Vacancy Migration Behavior in TiA1

摘要:

用分子动力学方法，采用Finnis-Sinclair类型的多体势，对TiAl中小尺寸空位团（N0=2,3,4）的各种可能构形进行了模拟计算，计算了空位团的形成能、结合能，分析讨论了容位团最稳定的构形，在此基础上，研究了空位团对单空位迁移的影响。计算结果表明：在TiAl合金中，组成空位团的每个空位都尽可能地与其它空位保持最近邻关系，空位团附近有反位原子。当空位团较大时，空位团周围的原子会向空位中心埸陷，类似于空位团中包含有间隙原子。已有的空位团可作为空位的凝聚中心具有捕获或吸收附近空位的能力。

Abstract:

The Molecular Dynamics Method with the Finnis Sinclair many body potential is used to calculate the formation energies and combination energies of some small vacancy clusters with different configurations in TiAl. The most stable configuration of a vacancy cluster and its effect on vacancy migration nearby the cluster are simulated and discussed. The results show that, in the most stable configuration, each vacancy makes its best endeavor to form nearest neighbor relationship with the other vacancies, and there are anti site defect nearby the cluster. The atoms nearby the vacancy cluster would move towards the cluster center for bigger cluster, and it seems that there exist interstitials in the vacancy cluster. The existing vacancy cluster as the aggregation center of vacancy has the ability of trapping or absorbing the near vacancy.