MD study of the dynamic behavior of small interstitial clusters in Fe

Dynamic behavior of small interstitial clusters (dislocation loops), such as the interaction with a self-interstitial atom (SIA) in Fe and the interaction between a SIA and an edge dislocation in Fe have been studied by means of molecular dynamics (MD) method in order to clarify their role in the evolution of damage structure during irradiation, especially in the so-called production bias effect through one-dimensional migration to sinks and in the so-called dislocation bias. Model crystal was constructed by using N-body potentials and small interstitial clusters, i.e., bundle of crowdions, a SIA and an edge dislocation were inserted. It was found that a SIA migrates to the edge dislocation core and finally the direction of the crowdion is converted to the direction parallel to the Burgers vector of the edge dislocation. Dynamic behavior of the loop, e.g., the interaction with a crowdion on a central 〈1 1 1〉 loop axis was also investigated as a function of time. It was shown that small initial cluster, e.g., I 19 in Fe is very mobile under the interaction with a crowdion, which shows that this interstitial cluster I 19 has already property of a dislocation loop of edge character and low Peierls potential for the motion of this loop, which is consistent with the straight edge dislocation in Fe.