Orientation-dependent crack-tip blunting and crack propagation in a single crystal BCC iron

Atomistic simulations of cracks with four different orientations in body-centered cubic single crystal iron are presented using molecular dynamics. Crystal orientation has considerable effect on the activation and evolution of crack propagation mechanisms. The results reveal that (a) crack-tip blunting depends on the crystallographic orientation, (b) continuous generation of dislocations form crack tip occurs for large crack-tip blunting, and (c) absence of deformation activities like dislocation generation, twin formation, etc. at the crack tip results in crack propagation in a brittle manner.