金属纳米线应力分布特征的原子级模拟研究

The stress characteristics of metal nanowires: an atomistic simulation study

运用分子静力学方法结合量子修正Sutten-Chen多体力场研究了Ni纳米线在平衡状态下的应力分布特征,考虑了三种不同取向的纳米线,即轴线方向分别沿[100],[110]和[111]方向的纳米线.计算的结果表明:由于表面张应力的作用,纳米线在弛豫过程中沿轴线方向长度发生收缩;纳米线从表面向中心区域呈现出由张应力向压应力连续分布的特征.随着纳米线直径的增加,纳米线的表面区域的张应力先上升,然后略有下降,并趋向一个非零的常值;而中心区域的应力则属于压应力,其值随着直径的增加显著地减小,并趋向于零值.无论是轴向收缩量,还是表面区域和内部区域的平均应力,均呈现出在[100]纳米线中为最大,而在[111]纳米线中为最小的趋势.

In this paper, we have used molecular statics calculations with the quantum corrected Sutten-Chen type many-body force field to study the stress distribution characteristic of nickel nanowires with [100], [110] and [111] crystallographic orientations in equilibrium state. The simulated results show that tensile stress on the surface of the nanowires causes them to contract along the length. It can be seen that the stress is tensile in surface region while compressive in core region. With the increasing of diameter, the average stress in core region is compressive and strongly decreased to approach to zero, while the surface tensile stress first increases, and then tends to a non-zero constant. The contraction ratio of length, and average stress in core and surface are always largest for [ 100] nanowire and smallest for [ 111 ] nanowire.