Evolution of Defect Cluster Distributions during Irradiation

Abstract

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Implications of defect clusters formed in cascades on free defect generation and microstructural development

“…Neither of these approaches takes into account that a significant fraction of the defects surviving the cascade event are in the form of small defect clusters which contribute to the sink strength. [26,27] In the following we will include the effects of defect clusters on the freely migrating defect population.…”

General introduction to microstructural evolution under cascade damage conditions

“…Along similar lines, Naundorf et al [40,41] showed that single defect pairs created at a sufficient distance (larger than the spontaneous recombination radius) from any other defects in a cascade would account for the observed magnitude of freely migrating defect fraction. Neither of these approaches takes into account that a significant fraction of the defects surviving the cascade event are in the form of small defect clusters which not only remove defects from those available for long-range migration, but also contribute to the sink strength and, therefore, reduce the lifetime of defects released into the matrix [42,43]. It should be emphasized that the quantity important for microstructural evolution is the "free defect population", i.e., the product of the number of defects released into the matrix and the average number of jumps the defects undergo before annihilation, rather than the number of defects released per se.…”

Freely-Migrating Defects: Their Production and Interaction with Cascade Remnants

“…Wiedersich [20] has suggested the following simple empirical expression to describe the fraction of freely-migrating defects, p(N), produced in cascades of various sizes:…”

“…More recently, Wiedersich [14,20] has examined the possible role of defect clusters in enhancing intercascade recombination, and therefore their role in reducing the number of freely-migrating defects. He argued that computer simulations indicate that only about one-half of the additional decrease arises from intracascade annealing at elevated temperatures, but that the larger observed decrease can be rationalized in terms of uncorrelated defect annihilation at previously produced clusters.…”