Molecular dynamics simulations were used to study defect production and disordering, in the primary cascade of radiation damage, as a function of the irradiation temperature. It was found that, although the number of Frenkel pairs decreased with increasing irradiation temperature, the size of the interstitial clusters and the interstitial clustering fraction increased with temperature. The temperature had a marked effect upon increasing the production of antisite defects. The number per cascade increased by about 20% as the irradiation temperature was increased from 100 to 600K. It then increased by about 90% as the irradiation temperature was increased from 600 to 900K. These effects were suggested to be due to an increase in the intensity and lifetime of the thermal spike. The average size of the simulated disordered zones at various temperatures was in reasonable agreement with experimental transmission electron microscopic data. The long-range order parameter in the cascade region was consistent with the values that were obtained experimentally for Ni3Al that was bombarded with ions to a similar dose. The chemical short-range order parameter was equal to about 0.6 over the whole range of irradiation temperatures which was considered. This suggested that the cascade core retained some short-range order at high temperatures, due to local reordering.

Temperature Effects on Defect Production and Disordering by Displacement Cascades in Ni3Al. Gao, F., Bacon, D.J.: Philosophical Magazine A, 2000, 80[7], 1453-68