Molecular dynamics simulation of fractures using an N-body potential

Molecular dynamics has been employed to model the fracture of a two-dimensional triangular atomic lattice. The N-body Sutton-Chen potential developed for fee metals and its extended version (Rafii-Tabar and Sutton) for fee random binary alloys were used for the interatomic interactions. It is shown that at low temperatures cleavage fractures can occur in both an elemental metal and an alloy. At elevated temperatures the nucleation of dislocations is shown to cause a brittle-to-ductile transition. For the brittle crack propagation in the elemental metal, crack propagation speeds have been computed for different stress rates, and a crack instability found to exist as the speed reaches a critical value of about 32% of the Rayleigh wave speed. For the random alloy, we find that the dislocation movement can be affected by the distorted lattice.