Progress in modelling the microstructural evolution in metals under cascade damage conditions

In recent years, it has been shown that intra-cascade clustering of vacanci es and self-interstitial atoms (STAs), differences in the thermal stability and mobility of the resulting clusters and one-dimensional (1-D) diffusion al glide of SIA clusters play a key role in damage accumulation in metals u nder cascade damage conditions. The model taking these aspects into account (production bias model, PBM) succeeded in rationalising striking features in the microstructural evolution in pure metals, where the conventional rat e theory model failed: the high overall swelling even at low dislocation de nsities, the enhanced swelling near grain boundaries, the decoration of dis locations with SIA loops, saturation of void growth and Void lattice format ion. In the present paper, the main ideas and results of these consideratio ns are reviewed. We discuss recent work on possible effects of deviations o f SIA cluster diffusion from strictly 1-D by direction changes and/or self- climb and formulate a general reaction kinetics including 1-D and 3-D clust er diffusion. Such reaction kinetics may be considered to form the basis fo r a general description of cascade damage accumulation in metals and comple x technical alloys. (C) 2000 Elsevier Science B.V. All rights reserved.