Investigation on mechanical properties of polycrystalline W nanowire

Abstract

Metal nanowires are stirring the attention of scientific world because of their many unique properties. W single crystal nanowires, with bcc crystal configuration, have become focus of many studies due to lack of complete insight of their mechanical deformation. However, polycrystalline W nanowires are not thoroughly studied yet. In this work, molecular dynamics simulation is used to identify different aspects of deformation and plasticity of polycrystalline W nanowire using EAM potential and a constant strain rate of 109s-1. Impact of grain size, diameter, and temperature on the elastic properties is analyzed. Average grain size is varied from 4.63nm to 25nm keeping the diameter constant at 5nm and temperature at 10K. Diameter of the nanowire is varied from 2 to 5nm keeping the average grain size and length to diameter ratio constant while temperature was changed from 10K to 500K maintaining fixed diameter and grain size. It is observed that inverse Hall-Petch behavior dominates the plasticity in polycrystalline nanowires and grain boundary sliding becomes the dominating mechanism of plasticity with a critical grain size. Nanowires with shorter diameter are found to be stronger and elevated temperature weakens the nanowire irrespective of the grain size.