The evolution of cascades of atom-atom collisions with primary knock-on atom energy increase

The evolution of cascades of atom-atom collisions with the increase of primary knock-on atom PKA energy in α-Fe is investigated with a molecular dynamics technique. The energy range studied was from 1.5 KeV up to 0.1 MeV. Besides, the effects of irradiated crystal temperature and of electron energy losses on the cascade development were taken into consideration. It was found that at high PKA energies and low temperatures a cascade appears to be a series of overlapping subcascades. The mechanism of their splitting is suggested which takes account of both the factor of PKA energy and the irradiated crystal temperature factor. The cascade splitting into several visible subregions occurs at elevated temperatures of the crystal. The origin of the splitting lies in the localization of single subcascades due to thermal vibrations of the crystal under irradiation