外应力作用下小角晶界的斜排位错运动研究

Inclined Dislocation Motion of Low Angle Grain Boundaries under Shear Force Exerting

关键词:  斜排位错  晶界瓦解  位错运动  建模

Key words:  inclined dislocations  grain boundary collapse  dislocation motion  modeling

摘要:

[目的]探讨纳米晶材料中小角度晶界位错在应力作用下的演化机理。[方法]通过分析位错受力,建立动力学方程,分析晶界斜排位错在受到外应力作用下的运动规律。[结果]晶界位错的3个部分结果不同,处在中心位错以上的位错(第1部分)在剪切应力不断增大的过程中,会经过滑移,波动,最后沿柏氏矢量方向滑移过程;中心位错(第2部分)会经过滑移,波动,再滑移过程;中心位错以下的位错(第3部分)会先逆柏氏矢量方向滑移,然后改变运动方向进行攀移,最后回到第5个位错的初始位置后沿柏氏矢量滑移。[结论]当晶界位错受到外应力作用时,晶界会马上瓦解,外应力是导致晶界瓦解的主要因素。对比水平位错的晶界,斜排位错组成的晶界瓦解不具有对称性,每个位错的运动规律都各有特点。

Abstract:

[Objective] An evolution process of the annihilation of small angle grain boundaries dislocation was researched in nanocrystalline materials in this paper.[Methods] Through the analysis of dislocation stress and the establishment of dynamics equations, the law of motion of grain boundary dislocations was studied under the external stress.[Results] For all of the inclined dislocations, grain boundary dislocations can be divided into three parts.In the first part, the dislocation above middle dislocation slips, swings, and finally slips along with the vector direction in the process of shear stress increasing.In the second part, the middle dislocation slips, swings, and slides again.In the last part, the dislocation below middle dislocation slips firstly along inverse direction of the vector, then changes direction for climbing, and finally returns back to the position of the fifth dislocation and slips along with the vector.[Conclusion] The results show that grain boundary soon collapses when affected by external stress, which is the main factor that leads to grain boundary collapse.In comparison with horizontal dislocation of grain boundary, inclined dislocation of grain boundary collapse is not symmetry, and each of the dislocation motion has its characteristics.