双位错滑移运动的晶体相场模拟

Phase-field-crystal Simulation of Double Dislocation Gliding

关键词:  晶体位错  滑移  应变  晶体相场

Key words:  crystal dislocation  gliding  strain  phase-field-crystal

摘要:

[目的]研究晶体位错运动对材料加工力学性能的影响。[方法]应用改进晶体相场(Phase-field-crystal,PFC)模型,研究剪切应变作用下晶体的双位错的滑移运动特征。[结果]在应变作用下,体系的双位错只作滑移运动,运动方向平行且相反,保持匀速运动,不出现攀移运动;应变率较小时,位错作滑移运动,越过势垒需要一定孕育时间,此时滑移出现颠簸式运动特征;应变率较大时,位错滑移运动呈匀速直线运动。[结论]PFC模型能较好地用于研究位错在应变作用下的运动。

Abstract:

[Objective] The effects of crystal dislocation movement on mechanical behaviors of materials processing are studied.[Methods] The feature of the gliding of double dislocation under shear strain are simulated by the improved phase-field-crystal(PFC).[Results] The simulation results show that the double dislocation of the system only glides without climbing under stress,and keeps moving at a constant speed,while their directions are parallel,but opposite.When the strain rate is small,it requires a certain incubation time to overcome the barrier,therefore,the slipping of dislocation looks like a bumpy way.When the strain rate is larger,the dislocation glides uniformly in a straight line,while the strain rate is relatively smaller,the gliding is of the bumpy motion.[Conclusion] PFC model can be well used to study the dislocation movement under the effect of strain.