First principles study on HenV clusters in α-Fe bulk and grain boundaries

Abstract

Based on the first-principles calculations, we studied the HenV clusters (n=1–9) in α-Fe bulk, and comparatively studied three orthogonal orientations of He2V clusters in the grain boundary (GB) plane of five symmetrical tilt grain boundaries (STGBs). The results of HenV clusters in bulk showed that HenV clusters with larger binding energy (He4V and He6V in this work) are more likely to exhibit a highly symmetrical configuration. Moreover, it is also indicated that the FeHe interatomic potential using an s-band model is more accurate than other potentials to describe the system. The grain boundary region (HenV (0≤n≤2) in a Σ5(310) GB as an example) was effectively used by constructing two simplified GB models (free surface GB model and reconstructed GB model) and the results proved that the free surface GB model is a good approximation by maintaining high precision (−0.09eV to +0.03eV binding energy error) and reducing resources consumption (24–90% computational time of the original GB model) as well. He2V residing in parallel to GB plane with relatively higher binding energies are more stable than the ones that perpendicular to it. He2V perpendicular to GB plane shows shorter HeHe separation distances than in bulk or tend to deviate from the orientation more easily to bind with GBs.