The nature of dislocation loops in neutron irradiated zirconium

The nature of the damage structure in neutron-irradiated zirconium has been studied using transmission electron microscopy. The damage structure consists of dislocation loops with a/3<112-0> Burgers vectors. No evidence was found for c component dislocation loops. The dislocation loops are non-edge in character and are elliptical with the loop minor axis in the (0001) plane and the major axis in the vicinity of the [0001] direction. This ellipticity was particularly marked for large vacancy loops whereas interstitial loops tended to be circular. Under all irradiation conditions studied, the loop populations were mixed interstitial/vacancy. (Auth.)