多晶粒银纳米线形变机理对温度依赖性的分子动力学研究

摘要

Based on molecular dynamics simulations,the plastic deformation of columnar polycrystalline silver nanowires under uniaxia] tension at different temperatures has been studied systematically.At a temperature below 200 K,the system with large grains deforms predominantly via the mechanism of dislocation slip,and the maximum yield strength remains relatively constant with temperature.When the simulation temperature is over 200 K,grain sliding gradually becomes the dominant deformation mechanism,especially for those samples with reduced grain size and the maximum yield strength shows a decrease with the increase of temperature.The temperature-dependence of the Hall-Petch relation has been discussed.%基于大规模分子动力学仿真,研究了包含多个晶粒的柱状银纳米线在不同温度下沿轴向拉伸形变的行为.结果表明,当温度低于200 K时,含较大晶粒的体系中位错滑移是其形变的主要机理,最大应力随温度变化不显著.当环境温度高于200 K时,晶粒的滑动逐渐成为形变的主导因素,这一特征在含更小晶粒的体系内表现更明显.同时最大应力随温度显著降低.基于上述结果,进一步讨论了温度对Hall-Petch关系的影响.