二维大取向角对晶界湮没过程的晶体相场模拟

Phase field crystal Simulation of Grain Boundary Annihilation with Two Dimensional Large Orientation Angle

关键词:  晶界  位错  大取向角  晶体相场模型

Key words:  grain boundary  dislocations  large angle of orientation  phase field crystal model

摘要:

[目的]针对大角正方相晶界的位错结构,揭示在外应变下的位错运动和位错反应的微观机理。[方法]采用双模晶体相场(PFC)模型,模拟大角度取向角位错湮没过程。[结果]晶界上的位错是由4个位错组成1个位错对。晶界湮没有如下主要过程:开始时位错沿晶界攀移,随后晶界发生位错分解并发射,位错运动方式由攀移转为滑移;滑移位错与其他位错在晶内相遇发生湮没,其余晶界位错进行攀移,再次出现晶界位错分解发射位错,位错滑移穿过晶界内部,到达对面晶界处发生湮没。在这个过程中部分位错滑移与其他位错相遇会形成新的位错,同样继续进行攀移、分解、滑移进而湮没的运动。[结论]PFC模型能较好地用于研究大角度正方相的位错在施加应力作用下的运动。

Abstract:

[Objective] Aiming at the dislocation structure of the large-angle square grain boundaries (GB),the microscopic mechanism of dislocation movement and dislocation reaction under external strain is revealed.[Methods] A dual-mode crystal phase field (PFC) model is used to simulate the dislocation annihilation process of large angle GB.[Results] Dislocations on the grain boundaries consist of 4 dislocations,which make up one dislocation pair.The grain boundary annihilation has the following main processes:At the beginning,the dislocations climb along the grain boundaries,then dislocations are disintegrated and emitted at the grain boundaries,and the dislocation movement is transferred from climbing to sliding; the slip dislocations and other dislocations encounter annihilation within the crystal and the rest of the grain boundary dislocations climb.Once again,the dislocations of the grain boundaries disintegrate and launch dislocations,and the dislocations slip through the grain boundaries and reach the opposite grain boundaries,and the annihilations occur.And in the process,some dislocations glide to encounter with other dislocations and form new dislocations.The same movement of climbing,decomposition,sliding and then annihilation will be continued.[Conclusion] The PFC model can be used to study the motion of large angle of orientation square phase dislocations under the action of stress.