Molecular dynamics modelling was used to investigate the effect of lattice temperature upon the production of vacancies and interstitials in the α-phase during the primary damage process of displacement cascades having energies of up to 20keV. The final number of Frenkel pairs decreased with increasing temperature due to an increase in the lifetime of the thermal spike at high temperatures. The production efficiency behaved in a similar manner to that simulated at 100K, but was further reduced and saturated at about 20% over the energy range considered at 600K. The number and size of clusters, both vacancy and interstitial, were increased by increasing the primary knock-on atom energy. The fraction of interstitials in clusters also increased with increasing lattice temperature. The interstitial clusters could glide back and forth via 1-dimensional migration along the crowdion direction at 100K. Small clusters of less than 4 self-interstitial atoms could change their glide direction onto, and off, basal-planes at 600K. It was also observed that single interstitials and some small clusters could migrate along the (11•0) and (¯22•3) directions at 600K. Clusters which contained up to 25 interstitials and 24 vacancies were formed by 20keV cascades at 600K, and almost all of the clusters had the form of a dislocation loop with a Burgers vector of 1/3(11•0). It was found that the 25-interstitial cluster was glissile, and dissociated on the basal and prismatic planes which formed its glide cylinder. Collapse of the 24-vacancy cluster into a perfect vacancy dislocation loop was found to occur in the primary damage process. This was due to the longer lifetime of the thermal spike at higher temperatures.

Temperature-Dependence of Defect Creation and Clustering by Displacement Cascades in α-Zirconium. F.Gao, D.J.Bacon, L.M.Howe, C.B.So: Journal of Nuclear Materials, 2001, 294[3], 288-98