A molecular dynamics study on the biased propagation of intergranular fracture found in copper STGB

Structural failure of the polycrystalline material is influenced by the interaction between the crystal and their boundaries. Specifically, a ductile material such as copper exhibit the different mechanisms of failure depending on the direction of the crack propagation within the grain boundary. Such directional anisotropy is often studied based on Rice's criteria, which has the analytic solution in the grain boundary with [110] rotation of the axis. In this work, we expand the study of such intergranular directionality to a propagation within [100] grain boundary. This work introduces the inherent bias found in the intergranular fracture of [100] grain boundaries, using molecular dynamics simulations. Later, such observation is shown to agree with the relative crack propagation velocities, and cohesive energies obtained at the crack tip vicinity. These anisotropic trends are lastly correlated with the detailed atomistic movements observed during structural failures. These findings are to be used in improving the simulation capability and predictability of crack propagation.