It was recalled that collision cascades in metals produced small interstitial clusters and perfect dislocation loops which glided via thermally activated 1-dimensional random walks. These gliding defects could change their Burgers vectors by thermal activation, or by interaction with other defects. Their migration was therefore of mixed 1- and 3-dimensional type and occurred along a 3-dimensional path which consisted of 1-dimensional segments. The defect reaction kinetics under mixed 1- and 3-dimensional diffusion were different to those under pure 1-dimensional diffusion and pure 3-dimensional diffusion; both of which could be formulated within analytical rate theory models of microstructure evolution under irradiation. Atomic-scale kinetic Monte Carlo defect migration simulations were used to investigate the effects of mixed 1- and 3-dimensional migration upon defect reaction kinetics; as a guide to incorporating such mixed migration into analytical rate theory. The dependence of sink strength upon the size and concentration of sinks under mixed-dimensional migration was shown to lie between that for pure 1-dimensional and pure 3-dimensional migration, and varied with the average distance, L, between the direction changes of gliding defects. It was shown that the sink strength in simulations which involved spherical sinks (radius R) under mixed-dimensional migration could be approximated, for values of L greater than R, by an expression which varied as R2. For small L-values, the form of the transition from mixed diffusion to pure 3-dimensional diffusion - as L decreased - was revealed by the simulations.

The Effects of One-Dimensional Glide on the Reaction Kinetics of Interstitial Clusters. H.L.Heinisch, B.N.Singh, S.I.Golubov: Journal of Nuclear Materials, 2000, 283-287, 737-40