Defect interaction processes controlling the accumulation of defects produced by high energy recoils

Defect interaction processes involved in the microstructural evolution during irradiation with high energy recoils are discussed on the basis of experimental observations. First of all, an experimental procedure is outlined for identifying the nature of small defect clusters produced in cascades and subcascades. The procedure was the growth and shrinkage behavior of clusters produced in the cascades during subsequent irradiations with 1 MeV electrons in a high voltage electron microscope. It is shown that the analysis of the clusters produced during irradiation with high energy recoils can be used to identify the formation of sub-cascades. Various aspects of the one-dimensional glide of small self-interstitial atom (SIA) clusters and their role in defect accumulation are considered. The experimentally observed dose dependence of the cluster density is used to discuss the problem of fission-fusion correlation. Finally, some comments are made on the role of stochastic fluctuation of point defect reaction in the stability and lifetime of SIA clusters under cascade damage conditions. (C) 1997 Elsevier Science B.V.