Primary radiation damage near grain boundary in bcc tungsten by molecular dynamics simulations

Molecular dynamics (MD) cascade simulations of single crystal and five bi-crystal structures in bcc tungsten (W) are conducted to investigate the role of grain boundaries (GBs) on defect production and the size distribution of defect clusters. The cascades in W with cascade energies of 10 keV and 20 keV are simulated at different distances from the GB plane at 4.2 K, 300 K and 900 K, respectively. The results indicate that the defect production is sensitive to the specific distance between the PKA and the nearby GB. The size of vacancy clusters becomes larger when the overlap region between the cascade and GB is small. Meanwhile, the mean size of interstitial clusters becomes smaller. The number of interstitials decreases with increasing temperature, whereas the number of vacancies is independent of the temperature.