不同加载条件下位错和溶质原子交互作用的数值模拟  

Simulations of the interactions between dislocations and solute atoms in different loading conditions

作　　者：何艳生[1] 符师桦[1] 张青川[1] 

机构地区：[1]中国科学技术大学近代力学系,中国科学院材料力学行为和设计重点实验室,合肥230027

出　　处：《物理学报》2014年第22期370-376,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11332010;51271174);国家重点基础研究发展计划(批准号:2011CB302105);中央高校基本科研业务费专项资金(批准号:WK2090050029)资助的课题~~

摘　　要：动态应变时效,即位错和溶质原子的动态交互作用,对合金材料的力学性质产生重要影响.本文基于蒙特卡罗方法,建立了"多位错-溶质原子"二维动力学模型,分别模拟了单位错-恒定应力率、多位错-无应力、多位错-恒定应力和多位错-恒定应力率四种条件下位错和溶质原子的演化过程.单位错-恒定应力率情况下,低应力率时位错被溶质原子钉扎而无法脱钉,高应力率时位错未被钉扎而一直运动,只有在适当应力率范围内,位错才呈现出反复的钉扎和脱钉;多位错-无应力时,溶质原子向正/负位错的下/上方偏聚;多位错-恒定应力时,位错运动受溶质原子钉扎的影响随应力增大而减小;多位错-恒定应力率时,集群化的钉扎和脱钉过程导致了位错总位移呈现阶梯状的演化.模拟结果表明:"位错-溶质原子"尺度上呈现了动态应变时效微观过程,与其理论描述相一致.Dynamic strain aging, i.e. the interaction between dislocations and solute atoms, affects the mechanical properties of alloys. In this paper, a 2D-kinetic Monte Carlo model relating to the interaction between dislocations and solute atoms is developed to simulate the motions of edge dislocations in four different conditions. In “single dislocation with constant stress rate” condition, single dislocation is pinned under low stress rate, moves continuously under high stress rate, and moves intermittently under middle stress rates. In “multi-dislocation with zero stress” condition, the solute atoms gather below positive dislocations and above negative dislocations. In “multi-dislocation with constant stress”condition, the influence of solute atoms on dislocation motion becomes stronger with stress decreasing. In “multi-dislocation with constant stress rate”condition, the collective pinning and unpinning result in the stepped curve of total displacement. The simulated results present the process of dynamic strain aging in a microscopic scale and are consistent with theoretical results.

关 键 词：动态应变时效 动力学模型 位错运动 

分 类 号：TG111[金属学及工艺—物理冶金]