Atomistic simulation of brittle fracture in nickel induced by He-doping

Molecular dynamics was used to study the effects of He-doping on brittle fracture in Ni. It was found that the released strain energy during crack propagation with He-doping ( Er) is higher than that without He-doping (E-r0). Enhancement of the strain energy due to He-doping contributes to a driving force to promote crack growth. This indicates that doping of He clusters in Ni favors crack growth, particularly for He clusters with high He-to-vacancy ratios, in which strong He-Ni interaction plays an important role. Furthermore, Er decreases non-linearly with increasing distance of He clusters away from the crack tip. Our results show that embrittlement of the materials will be enhanced when either the He concentration or the fracture density is above a critical value. The effect of critical He concentration on embrittlement of the materials has been reported in experimental studies.