Dynamic crack propagation in copper bicrystals grain boundary by atomistic simulation

Grain boundaries (GBs) dependent crack propagation has been observed in previous experiments, which shows strong anisotropy of cracks propagation behaviors in nanocrystalline. In this paper, the propagation behaviors of central cracks at different symmetrical tilt GBs in bicrystalline copper are studied by using atomistic simulations. Three different modes of interfacial crack propagation are found: crack prefers to propagate in a brittle manner along GB; crack propagates with voids and coalescence ahead of the crack tip, and blunts in the opposite direction; crack blunts at both two tips of the crack. Furthermore, thermo effects on the crack propagation are also investigated in our simulations. It is found that the mode of crack propagation at a certain GB changes from brittle to ductile at a critical temperature, which is different for the GB with different crystalline structures.