Suppression of interstitial cluster diffusion by oversized solute atoms

We study the diffusion of self-interstitial atom (SIA) clusters in metals with oversized substitutional impurities. Kinetic Monte Carlo (kMC) simulations are performed which include elastic interactions between defects. We show that the SIA clusters can become confined in a 1-D segment between impurity atoms due to repulsion from these stress centres. Rare rotation of the easy direction of motion of the clusters allows them to escape to new confined segments. This suppressed diffusion is examined by both kMC simulations and an analytic theory, which are shown to agree well. We suggest some of the possible applications of these findings to radiation damage resistance in structural materials for fusion devices.