The damage which was produced, in hexagonal close-packed metal at 100K, by displacement cascades with energies ranging from 0.3 to 5keV was investigated by using molecular dynamics methods and a many-body interatomic potential. It was found that there was no appreciable effect of primary knock-on atom direction, and that individual replacement sequences made only a minor contribution to the final damage state. In comparison with Ti, fewer atoms in Zr were temporarily displaced to interstitial sites during the collisional phase, and the cascade core size was smaller. On the other hand, the core temperature during the thermal spike was higher. The number of Frenkel pairs which was produced in the final damage state was smaller in Zr than in Ti, and the efficiency of their production declined with increasing cascade energy; as in all other metals. Some interstitial clusters were formed in the cascade process. They had a dislocation-like character, and migrated preferentially along basal planes during and after the thermal spike. An analysis of the mean-square atom displacements in the final state of 2 and 5keV cascades showed that the atomic mixing in Zr was about half of that reported for a-Ti.

A Molecular Dynamics Study of Displacement Cascades in a-Zirconium S.J.Wooding, D.J.Bacon: Philosophical Magazine A, 1997, 76[5], 1033-51