Atomic-scale computer simulations were used to study the thermally activated atomic transport of self-interstitial atoms in the form of planar clusters in pure Cu. It was recalled that there was strong evidence that such clusters were commonly formed in metals during irradiation with high-energy particles, and played an important role in the accumulation and distribution of the surviving defects. An extensive study of the mobility of self-interstitial atom clusters which contained 2 to 331 interstitials was carried out by using molecular dynamics simulations techniques at 180 to 1200K. The results obtained showed that clusters which were larger than 3 to 4 self-interstitial atoms in size were 1-dimensionally mobile. Large clusters, with more than 100 self-interstitial atoms, exhibited a significantly reduced mobility. An attempt was made to describe the mobility of self-interstitial atoms clusters within the 1-dimensional diffusion approximation. The effective cluster migration energy for 1-dimensional diffusion - as estimated from the jump frequency of the cluster center-of-mass - was found to be independent of the number of self-interstitial atoms in the clusters; although the cluster jump frequency decreased with increasing cluster size.

One-Dimensional Atomic Transport by Clusters of Self-Interstitial Atoms in Iron and Copper. Y.N.Osetsky, D.J.Bacon, A.Serra, B.N.Singh, S.I.Golubov: Philosophical Magazine, 2003, 83[1], 61-91