A study was made of cleavage versus blunting dislocation-emission from a crack at an interface in a 2-dimensional simple hexagonal lattice. Various nearest-neighbor central force laws were assumed, and the results were compared with predictions expressed in terms of interfacial surface energy and unstable stacking-fault energy. The mode conversion which was characteristic of interfacial cracks was interpreted in terms of a local phase at the core of the crack, with a cut-off at the force-law range parameter. It was found that the emission criterion fell into 2 regimes. When the interfacial surface energy was greater than 3 times the unstable stacking-fault energy, the emission criterion was proportional to the product of the energies. When the interfacial surface energy was less than 3 times the unstable stacking-fault energy, the emission criterion was proportional to the unstable stacking-fault energy alone.

Intrinsic Ductility Criterion for Interfaces in Solids. R.Thomson: Physical Review B, 1995, 52[10], 7124-34