Effects of undersized Fe atoms on the stability of interstitials near a dislocation core in V studied by molecular dynamics simulation

Abstract

It is well-known that the dislocation bias should be responsible for the large swelling. In V-Fe alloys, the extremely large swelling has been observed, which indicates that undersized Fe atoms must play a significant role for the modification of one-dimensional (1D) motion. In the present study, we performed molecular dynamics (MD) simulations with a newly constructed empirical potential based on the Finnis-Sinclair (FS) type embedded atom method (EAM) to investigate the effects of undersized Fe atoms on the static and dynamic properties of the interstitial migration under the strain field of several sizes of interstitial loops and an edge dislocation. The results show that the undersized Fe atoms tend to form a stable mixed-dumbbell configuration and the activation energy of migration towards a dislocation core is much lower than that of SIAs. Moreover, for V-Fe dumbbell the relative probability for intermediate configurations between 〈111〉-crowdion and 〈110〉-dumbbell below an edge dislocation core becomes significantly higher compared to that of V-V dumbbell. These results indicate that it is very likely that the continuous absorption of interstitial Fe atoms by a dislocation core would be possible and enhances the swelling in V-Fe alloys.