RADIATION-INDUCED DISORDERING AND DEFECT PRODUCTION IN CU3AU AND NI3AL STUDIED BY MOLECULAR-DYNAMICS SIMULATION

We use molecular dynamics computer simulations to investigate the kine tics of disordering induced by energetic displacement cascades in two ordered intermetallics, Cu3Au and Ni3Al. We also study the mechanisms of defect production in these systems and compare the results to recen t findings in pure metals. We employ embedded atom Potentials which re produce the main features of the phase diagram, including a disorderin g transition below the melting point (T(m)) in Cu3Au and an ordered co mpound up to T(m) in Ni3Al. We simulate events with 5 keV recoil energ y in crystals containing up to 157216 atoms at 10 K. We present result s of the influence of the displacement cascade on the order parameters and describe their temporal and spatial evolution. We discuss atomic mixing in the cascade regions in terms of the atomic mobilities in eac h sublattice. The influence of the ordering energy and the melting tem perature in the behavior of the compounds is emphasized.