单向拉伸作用下Cu(100)扭转晶界塑性行为研究

应用分子动力学方法研究了在不同扭转角度下的Cu（100）失配晶界位错结构，以及不同位错结构对晶界强度的影响.模拟结果表明：小角度扭转晶界上将形成失配位错网，失配位错密度随着晶粒之间的失配扭转角度的增加而增加.变形过程中，位错网每个单元中均产生位错形核扩展.位错之间的塞积作用影响晶界的屈服强度：随着位错网格密度的增加，位错之间的塞积作用增强，界面的屈服强度得到提高.大角度扭转晶界将形成面缺陷，在变形中位错由晶界角点处形核扩展，此时由于面缺陷位错开动应力趋于一致，因此晶界的临界屈服强度趋于定值. 关键词： 扭转晶界 失配位错网 强化机理 分子动力学

Molecular dynamical investigation on plastic behavior of Cu(100) twist-grain boundary under uniaxial tension

Misfit dislocation structures at twist-grain boundary and its effect on grain boundary strength are investigated by using molecular dynamics simulation with EAM potential. The results reveal that the density of misfit dislocations which are formed on small angle twist-grain boundary is increased as the twist angle increased. Dislocations nucleate at each unit of the dislocation networks and the yield stress is increased as the density of misfit dislocations increases since grain boundary is strengthened by the interaction between dislocation networks. Face defect is formed at large angle twist-grain boundary, and the dislocations nucleate at the atomically sharp corner of the grain boundary. The yield stress is kept almost at the same value since there is little effect on the nucleation force of dislocation on face-defect grain boundary.