Effect of Strain Field on Threshold Displacement Energy of Tungsten Studied by Molecular Dynamics Simulation

The influence of strain field on defect formation energy and threshold displacement energy (E_\rm d) in body-centered cubic tungsten (W) is studied with molecular dynamics simulation. Two different W potentials (Fikar and Juslin) are compared and the results indicate that the connection distance and selected function linking the short-range and long-range portions of the potentials affect the threshold displacement energy and its direction-specific values. The minimum E_\rm d direction calculated with the Fikar potential is \langle100\rangle and with the Juslin potential is \langle111\rangle. Nevertheless, the most stable self-interstitial configuration is found to be a \langle111\rangle-crowdion for both the potentials. This stable configuration does not change with the applied strain. Varying the strain from compression to tension increases the vacancy formation energy while decreases the self-interstitial formation energy. The formation energy of a self-interstitial changes more significantly than a vacancy such that E_\rm d decreases with the applied hydrostatic strain from compression to tension.