Static and molecular dynamics simulations were used, together with various types of interatomic potential, to investigate the properties of self-interstitial atomic clusters which were produced during irradiation. In the case of α-Fe, faulted clusters of <110> dumb-bells were unstable for all of the potentials. The most stable self-interstitial atomic clusters were sets of parallel <111> crowdions. Large clusters of this type formed perfect dislocation loops with a Burgers vector of ½<111>. Small (less than 9 self-interstitial atom) clusters of <100> crowdions were stable at 0K, but transformed into a set of <111> crowdions during annealing. Larger <100> clusters were stable, and formed perfect dislocation loops with a Burgers vector of <100>. Both types of loop were glissile. In the case of Cu, clusters of parallel <100> dumb-bells and <110> crowdions were stable. Large clusters of these types formed faulted and perfect dislocation loops with Burgers vectors of 1/3<111> and ½<110>, respectively. Small (less than 7 self-interstitial atom) faulted clusters of irregular shape could transform into a set of <110> crowdions during annealing. Larger faulted clusters were stable as hexagonal 1/3<111> Frank loops, for a period of several hundred ps, at temperatures of up to about 1050K. All of the faulted clusters were sessile. Clusters of <110> crowdions and ½<110> perfect loops were glissile and stable at all temperatures. When sufficiently large (more than 49 to 64 self-interstitial atoms), they could dissociate on their glide prism. Symmetrical 3-dimensional clusters of <100> dumb-bells were stable at 0K but, during annealing, they transformed into sets of <110> crowdions. The results for Fe and Cu were compared with experimental data, and were used to explain observed differences in the radiation damage accumulation behaviours of face-centered cubic and body-centered cubic metals.

Structure and Properties of Clusters of Self-Interstitial Atoms in FCC Copper and BCC Iron. Y.N.Osetsky, A.Serra, B.N.Singh, S.I.Golubov: Philosophical Magazine A, 2000, 80[9], 2131-57