Dynamic interactions of helium-vacancy clusters with edge dislocations in α-Fe

The effects of He-vacancy (He-V) clusters on the mobility of an a/2〈1 1 1〉{1 1 0} edge dislocation in α-Fe are investigated by atomic simulation with empirical potentials at 0 K. A number of small He n V m ( n/ m 0–4) clusters initially placed at the same position on the slip plane are comparatively studied. The results show that the interaction of He-V clusters with edge dislocations depends on not only the helium-to-vacancy (He/V) ratio, but also the cluster size. The small He-V clusters with low He/V ratios have a small effect on the dislocation mobility, but the larger clusters with higher He/V ratios significantly increase the critical resolved shear stress for dislocation glide. One of interesting results is that the He-V clusters almost stay at their original positions, and do not move along with the dislocation.