Paving a way to suppress hydrogen blistering by investigating the hydrogen-beryllium interaction in tungsten

We have investigated the hydrogen-beryllium (H-Be) interaction and the behavior of Be in tungsten (W) in order to explore the influence mechanism of Be on H using a first-principles method. A single Be atom is energetically favorable sitting at the octahedral interstitial site (OIS) instead of the tetrahedral interstitial site (TIS), and prefers to diffuse along the OIS → TIS → OIS path. Interestingly, it has been demonstrated that there is large binding energy between Be atoms in W (>1 eV), leading to them energetically clustering. This can be attributed to the strong Be-W repulsion and the intrinsic electrophobic properties of Be. Further, it is found Be has significant effect on H behavior in W. On the one hand, the interstitial Be atom can enhance the stability of H in W, and thus it can serve as a trapping center for H, due to the redistribution of electron density induced by Be. This will block H diffusing deeper into the bulk, leading to the decrease of H retention in W. On the other hand, the H trapping capability of vacancy will be severely weakened by Be, because Be will provide electrons to vacancy resulting in the increasing of the electron density. Hence, the Be-V complex only can hold 5H atoms, 58.3% less than that of the Be-free vacancy, and there is no H₂ molecule formation. This indicates Be could suppress H bubbles formation in W. Consequently, H retention and blistering in W can be suppressed by doping Be.