晶体相场模拟取向角对晶界湮没过程的影响

Phase-field-crystal Simulation of Effect of Different Orientation Angle on Annihilation of Grain Boundary

关键词:  晶界  位错湮没  取向角  晶体相场模型

Key words:  grain boundary  dislocation annihilation  orientation angle  phase-field-crystal model

摘要:

[目的]研究大角晶界的位错运动和相互作用,揭示晶界发射位错的内在原因。[方法]采用晶体相场模型模拟不同取向角的晶界位错湮没过程。[结果]晶界湮没有如下主要过程:开始时位错沿晶界攀移,随后晶界发生位错发射,位错运动方式由攀移转化为滑移;位错滑移穿过晶粒内部,在到达对面晶界处发生湮没;其余的晶界位错仍作攀移运动,再次出现晶界发射位错;滑移位错与其它位错在晶内相遇发生湮没。[结论]位错在晶界处湮没,自由能曲线的谷较浅,而在晶粒内部湮没,能量曲线的谷较深;晶界攀移的位错越多,能量曲线的峰越高。

Abstract:

[Objective] The dislocation motions and their interaction of grain boundary are analyzed to reveal the intrinsic reason of emission dislocation of grain boundary.[Methods] Grain boundaries (GB) with different orientation angles under strains are simulated by phase-field-crystal (PFC) model.[Results] The process of the GB decay can be divided into several main typical stages as follows:Dislocation climbs firstly along the GB,and then the GB emits pair dislocations to glide in grain instead of climbing along GB; gliding for a while,the dislocation crosses the grain and annihilates at the opposite side of grain boundary.The remains of dislocation in the GB can still climb along the GB,and then the GB emits the dislocations to glide again.Gliding dislocations encounter with other dislocations inside the grain and the annihilation occurs.[Conclusion] The valley for dislocation annihilation on GB is shallow,while that inside the grain is deep.The more the numbers of dislocation for climbing are,the higher the peak of the curve is.