单晶Cu(001)薄膜塑性变形的分子动力学模拟

Plastic deformation of single-crystalline copper films with surface orientation [001]:molecular dynamics simulations

使用分子动力学方法,模拟研究了单晶Cu(001)薄膜在双向等轴拉伸应变下的塑性变形行为.当应变超过一定值时,样品通过产生位错、层错及孪晶而发生塑性变形.当应变相对较低时,不全位错首先在薄膜表面形核并在密排面上滑移,留下堆积层错;当应变增加时,位错在表面与内部同时成核生长,层错数量也随之增加.分析了相邻滑移面上的位错之间相互作用形成孪晶的微观过程.材料内部形成大量堆积层错及孪晶后,较大孪晶的密排面上的原子也会发生滑移,形成孪晶内部的层错结构以释放残余应力.

Molecular dynamics simulations are performed to study the plastic deformation behavior of single-crystalline copper film subjected to biaxial tensile strain.The unltrathin film is oriented normal to the [001]crystallographic direction.Beyond a critical value,the film deforms plastically through nucleation,motion and interaction of dislocations.The progress of twinning formed by the motion of Shockley partial dislocations in successive atomic planes is analyzed.Additional stacking faults bounded by twin boundaries are formed in some large newborn twins to release residual strain.