PNNL

Abstract

In order to help understand the evolution of stacking fault tetrahedra (SFTs) in a cascade producing irradiation environment, the available information on the behaviour of SFTs observed under different experimental conditions has been briefly reviewed. Effects of thermal annealing and irradiations on the stability of pre-existing SFTs produced by quenching and aging are also included in the review. Some results on the effects of thermal annealing of irradiation-induced SFTs are presented and discussed. The analysis of these observa-tions leads to three significant conclusions: (a) during irradiation SFTs pro-duced in the cascades are likely to interact with vacancies, self-interstitial at-oms (SIAs) and SIA clusters, (b) interaction with SIAs and their clusters may cause both shrinkage and transformation of SFTs into Frank loops and (c) both during irradiation and annealing the lifetime of SFTs is determined not only by their thermal stability but also by their stability against transformation to loops. These facts must be taken into account in the theoretical treatments of damage accumulation.