剪切作用下Cu(100)扭转晶界塑性行为研究

本文采用分子动力学方法研究了在剪切载荷作用下,Cu(100)扭转晶界对Cu柱屈服强度的影响.模拟结果发现,在加载过程中,低角度扭转晶界形成的位错网发生位错形核与扩展,位错之间的塞积作用提高了Cu柱的屈服强度;对于高角度扭转晶界,晶界发生滑动降低了Cu柱的屈服强度.同时发现,随着扭转角度的增加,Cu柱的屈服强度先增大,当扭转角度大于临界角度时,Cu柱的屈服应力逐渐减小.这表明剪切载荷作用下,两种不同的机理主导Cu柱的屈服,对于小于临界角度的扭转晶界,Cu柱的屈服由晶界位错形核和扩展机理主导,对于大于临界角度 关键词： 扭转晶界 分子动力学 位错形核 晶界滑移

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

By using molecular dynamics with EAM potential, yield strength of copper column with (100) twist grain boundary and twist grain boundary effect are investigated under shear load. The results reveal that dislocations nucleate at the misfit dislocation network of low-angle twist grain boundary and dislocations stacking influence the yield strength of copper column. For high-angle twist grain boundary, twist grain boundary sliding decreases the yield stress of copper column. Meanwhile it is found that, with increasing twist angle, copper column yielding strength increases firstly. When twist angle reaches the critical value, the yielding strength decreases with increasing twist angle. It is concluded that different mechanisms mediate the yielding of copper column. Dislocation nucleation controls the yield stress of copper column for low-angle twist grain boundary and yielding of copper column is dominated by grain boundary sliding for high-angle twist grain boundary.