Effect of irradiation and irradiation defects on the mobility of Σ5 symmetric tilt grain boundaries in iron: An atomistic study

Body center cubic iron materials are commonly used in nuclear power plants. In bcc-iron, symmetric tilt grain boundaries (STGBs), which are believed to play important roles on self-healing, are susceptible to configuration and structural change under irradiation. The effect of such changes on mechanical properties of such GBs is still unknown. In this work, using molecular dynamics simulations, we find that the critical shear stress τc required for Σ5 STGB migration is greatly reduced by either displacement cascade nearby or absorption of defect clusters. Moreover, we find that the trapping of radiation-induced interstitial-type dislocation loops could also decrease τc, indicating that displacement cascades could also exert a long-range effect on GBs due to the fast diffusion of interstitial clusters.