STOCHASTIC ANNEALING SIMULATION OF INTRACASCADE DEFECT INTERACTIONS

Atomic scale computer simulations are used to investigate the intracas cade evolution of the defect populations produced in cascades in coppe r over macroscopic time scales. Starting with cascades generated using molecular dynamics, the diffusive transport and interactions of the d efects are followed for hundreds of seconds in stochastic annealing si mulations. The temperature dependencies of annihilation, clustering an d free defect production are determined for individual cascades, espec ially including the effects of the subcascade structure of high energy cascades. The subcascade structure is simulated by closely spaced gro ups of lower energy MD cascades. The simulation results illustrate the strong influence of the defect configuration existing in the primary damage state on subsequent intracascade evolution. Other significant f actors affecting the evolution of the defect distribution are the larg e differences in mobility and stability of vacancy and interstitial de fects and the rapid one-dimensional diffusion of small, glissile inter stitial clusters produced directly in cascades. Annealing simulations are also performed on high-energy, subcascade-producing cascades gener ated with the binary collision approximation and calibrated to MD resu lts. (C) 1997 Elsevier Science B.V.