ASPECTS OF MICROSTRUCTURE EVOLUTION UNDER CASCADE DAMAGE CONDITIONS

The conventional theoretical models describing the damage accumulation , particularly void swelling, under cascade damage conditions do not i nclude treatments of important features such as intracascade clusterin g of self-interstitial atoms (SIAs) and one-dimensional glide of SIA c lusters produced in the cascades. Recently, it has been suggested that the problem can be treated in terms of 'production bias' and one-dime nsional glide of small SIA clusters. In the earlier treatments a 'mean size approximation' was used for the defect clusters and cavities evo lving during irradiation. In the present work, we use the 'size distri bution function' to determine the dose dependence of sink strengths, v acancy supersaturation and void swelling as a function of dislocation density and grain size within the framework of production bias model a nd glide of small SIA clusters. In this work, the role of the sessile- glissile loop transformation (due to vacancy supersaturation) on the d amage accumulation behaviour is included. The calculated results on vo id swelling are compared with the experimental results as well as the results of the earlier calculations using the 'mean size approximation '. The calculated results agree very well with the experimental result s. (C) 1997 Elsevier Science B.V.