高温应变下的晶界位错结构组态演化的晶体相场模拟

Phase Field Crystal Simulation of Evolution of Grain Boundary Dislocation Structure under High Temperature Strain

关键词:  晶界位错  晶体相场  位错反应  应变

Key words:  dislocation of grain boundary  phase-field-crystal  dislocation reaction  strain

摘要:

[目的]研究高温下晶体的晶界位错结构组态演化。[方法]采用晶体相场（PFC）方法模拟高温条件下小角对称倾侧晶界结构，研究施加x轴方向拉应变和y轴方向压应变作用下晶体的晶界位错的迁移、增殖和湮没。[结果]在施加应变的作用下，晶界位错迁移出晶界向晶粒内部移动，在位错增殖和湮没的过程中发生位错反应。[结论]位错增殖的本质是产生了分布于晶界两侧的对称位置数量相等且Burgers矢量总和为0的多组位错对。在晶界处新增殖的位错对，其左侧和右侧位错对的Burgers矢量之和分别不为0且方向相反。在位错增殖和湮没的过程中，样品的总Burgers矢量是守恒的，总是等于初始晶界处的位错组A的Burgers矢量。

Abstract:

[Objective] The configuration evolution of grain boundary dislocation structure of crystals at high temperature is studied.[Methods] The phase field crystal (PFC) method is used to simulate the small-angle symmetric tilting grain boundary structure,and the migration, proliferation and annihilation of grain boundary dislocations under the application of x-axis tensile strain and y-axis compressive strain are studied.[Results] Under the action of strain, the dislocations of the grain boundary migrate out of the grain boundary to move into the grain, and the dislocation reaction occurs during the process of dislocation proliferation and annihilation.[Conclusion] The essence of dislocation proliferation is the generation of multiple sets of dislocation pairs with equal number of symmetric positions distributed on both sides of the grain boundary and the sum of the Burgers vectors is zero.The sum of the Burgers vectors of the left and right dislocation pairs which newly generated at the grain boundary is not 0 and their vector directions are opposite,respectively. During the process of dislocation proliferation and annihilation,the total Burgers vector of the sample is conserved,always equal to the Burgers vector of the dislocation group A at the initial grain boundary.