In order to clarify the behavior of defects under bombardment, a model austenitic alloy was treated with heavy ions while changing the temperature in a step-wise manner from 473 to 773K and from 573 to 773K. It was found that most of the interstitial loops which were formed by pre-irradiation, at 473 or 573K, disappeared during the initial stages of subsequent bombardment at 773K. Upon increasing the dose at 773K, the size and density of loops again increased. The behavior of loops during 773K irradiation was affected not only by the dose but also by the pre-irradiation temperature. The results were analyzed by using rate theory for defect clustering. Numerical calculations indicated that the bombardment-induced resolution of small vacancy clusters temporarily brought about vacancy-predominant conditions by changing the temperature from low to high, and resulted in the shrinkage of interstitial loops.

Q.Xu, H.Watanabe, N.Yoshida: Journal of Nuclear Materials, 1996, 233-237B, 1057-61