The effect of collision cascades upon pre-existing point defects in crystalline materials was studied by simulating 5keV collision cascades. The results indicated that collision cascades did not significantly affect interstitials or vacancies outside of the liquid core of the cascade although, in face-centered cubic metals, heating of the crystal by the cascade caused some thermal migration of the interstitials. Within the liquid cascade core, both interstitials and vacancies moved towards the center of the molten region when it re-solidified, and recombined or clustered there. At high temperatures, random jumping of interstitials during the thermal-spike phase could cause significant additional trapping of interstitials in the liquid.

Point Defect Movement and Annealing in Collision Cascades K.Nordlund, R.S.Averback: Physical Review B, 1997, 56[5], 2421-31