FRACTURE PROPERTIES OF METALS AND ALLOYS FROM MOLECULAR-DYNAMICS SIMULATIONS

Molecular dynamics simulations of fracture have been performed on the metals Al and Nb, and the intermetallic alloys RuAl, Nb3Al and NiAl. The forces and energies were modelled with embedded atom method potentials. The increasing external stress was applied using displacements of the outer boundaries of the array, calculated by anisotropic elasticity theory, until the pre-existing cracks propagated or dislocation nucleation occurred. The resulting critical stress intensity factor was calculated at various orientations and temperatures, and the results compared with theory. Observations of slip systems are reported, as well as values for surface energies and ''unstable stacking'' energies.