纳米丝应变率效应的分子动力学模拟

A MOLECULAR DYNAMICS SIMULATION OF THE STRAIN RATE EFFECTS ON NANOWIRE

采用分子动力学模拟了零温时不同应变率作用下纳米丝的拉伸力学行为。计算结果表明在缺乏热激活软化机制条件下,纳米丝应变率效应呈现出与宏观应变率试验结果相一致的特征。纳米丝在不同的应变率范围具有不同的变形机制。在应变率不敏感区和敏感区,纳米丝主要以位错运动作为塑性变形机制;在应变率突变区,纳米丝通过局部原子混乱区的持续扩展乃至整体结构的非晶化作为塑性变形机制。

Nanowire's tensile properties under different strain rates are simulated using Molecular Dynamics Method at 0 K. The results demonstrate that, without the thermo softening mechanism, the relationship between strenght and strain rate for nanowire almost exhibits the same trend as those of the macro ecperimental results. In addition, the deformation mechanism varies in different range of strain rates. In the sensitive and non-sensitive regions, dislocation behaviors dominate plasic deformation; while in the sharp-changed region, the main source causing plastic deformation is the successive expansion of the local disordered areas until the amorphization of the whole nanowire.