小角对称晶界及亚晶界湮没过程的晶体相场模拟

【目的】研究六角相的位错相互作用的情况,以揭示其运动及能量变化规律。【方法】采用晶体相场(Phase-Field Crystal,PFC)模型,模拟小角对称双晶所形成的晶界及亚晶界在应力作用下的湮没机制,并从位错运动及能量变化角度分析该机制。【结果】亚晶界运动分为3个阶段:第一阶段是体系能量增加,反映了位错的攀移和滑移过程,以及生成的亚晶界迁移;第二阶段是体系自由能量降低的阶段,反映了亚晶界位错相互之间靠近吸引,发生湮没的过程;第三阶段是重复前两个阶段,最后位错全部湮没消失,形成完整单晶。【结论】PFC模型能较好地用于研究六角相双晶在施加应力作用下由位错形成的晶界(包括亚晶界)的运动。

Phase Field Crystal Study on Small Angle Symmetry Grain Boundary and Sub-Grain Boundary Annihilation Process

Objective] The dislocation interaction in the six angular phase is studied to reveal its movement and energy variation.Methods] The phase field crystal (PFC) model is used to simulate the annihilation mechanism of the grain boundary and sub-grain boundary formed by small-angle symmetric double crystal under the stress action, and the mechanism is analyzed from the perspective of dislocation motion and energy change.Results] The movement of sub-grain boundary is divided into three stages:The first stage is the increase of the system energy, reflecting the migration and slip process of dislocations and the migration of the sub-grain boundary. The second stage is the stage of the reduction of the system free energy, which reflects the close proximity of the sub-grain boundary dislocation to interaction and the annihilation process occurs. The third stage is to repeat the first two stages, and finally all dislocations will annihilate to form a perfect single crystal.Conclusion] PFC model can be used to study the movement of grain boundaries (including sub-grain boundaries) formed by dislocations under the action of stress by hexagonal bi-crystals.