Atomistic simulation of interaction of collision cascade with different types of grain boundaries in α-Fe

Abstract

Presented here are atomistic simulations of the interaction of a collision cascade in α-Fe with different types of grain boundaries (GBs). The collision cascade was generated by a primary knock-on Fe atom of 3 keV kinetic energy. Four different types of symmetric tilt GB configurations (low angle and high angle GBs, Σ3 and Σ11 GBs) with two tilt axes [112¯] and [1¯10] were considered. Difference in potential energy, strength and average displacement of atoms between pristine and irradiated GB configurations were analysed to bring out the effect of irradiation. The vacancy and interstitial formation energies calculated using molecular statics simulations were found to be lower in the GB than in the grain. Collision cascade resulted in defect clusters in and around the GB. Low angle GBs were found to be better sinks for radiation induced defects. Tensile deformation of the irradiated configurations resulted in dislocation loops being nucleated from interstitial clusters. The loss in strength after irradiation was high for Σ3 GBs and negligible for other GBs. It was suggested that materials with low angle GBs and a high dislocation density would be preferred for use in radiation environment.