Replacement collision sequence studies in iron

Abstract

The properties of replacement collision sequences (RCS) in iron and their contribution to radiation damage are studied as they are generated in atomic collision cascades with the binary collision approximation Marlowe. Length distributions of RCS in collision cascades generated by primaries with a couple of ten keV kinetic energies are predicted short. Whatever the interatomic potential employed, at least 90% of the generated RCS have a length of no more than three successive collisions, whatever the directions. This property was found for all the known phases of iron at standard pressure (bcc and fcc). The RCS length distributions are not significantly influenced by the temperature nor by the accurate form of the model describing the energy loss in RCS. Close to 50% of the stable Frenkel pairs (FP) created result from RCS that are shorter than the vacancy–interstitial recombination distance estimated on the basis of molecular dynamics calculations. The other half results from longer RCS (about five successive collisions or more) that are particularly efficient in FP production. This suggests that such RCS are no focusing chains.