Computer simulation of displacement cascade effects in metals

Significant advances have been made over the past decade in using computer simulation to investigate the mechanisms associated with defect production by displacement cascades in metals. As reported at COSIRES '92 by Diaz de la Rubia er al. (Rod Eff. mid Def. Sol. 130-131 (1994) 39) and COSIRES '94 by Bacon et al. (Nucl. Instrum. and Meth. B 102 (1995) 37) a variety of metals of different crystal structure have been modelled over primary-knock-on energies from the threshold for displacement up to several keV, and these studies have shed considerable light on the physics of the cascade process by utilising realistic interatomic potentials with reasonably large model size. They have also shown that the efficiency for production of Frenkel defects is much less than the estimates given by earlier binary-collision models, and that self-interstitial atoms can actually form clusters during the cascade process itself. The present review updates the 1994 paper by discussing more-recent simulations that have gone beyond those referred to above. It includes research dealing with effects on defect formation of cascade energy, irradiation temperature, alloying (solid solutions, ordered alloys and precipitates), and the presence of a nearby surface. Issues such as defect clustering and cascade overlap are also reviewed. The overall aim is to demonstrate that computer simulation still provides a unique means of gaining information on cascade damage processes in metals.