Role of helium in the sliding and mechanical properties of a vanadium grain boundary: A first-principles study.

The effects of helium (He) on the sliding and mechanical properties of a vanadium (V)Σ5(310)/[001] grain boundary (GB) have been investigated using a first-principles method. It has been found that He was energetically favorable sitting at the GB region with a segregation energy of −0.27 eV, which was attributed to the special atomic configurations and charge density distributions of the GB. The maximal sliding energy barrier of the He-doped GB was calculated to be 1.73 J/m2, ∼ 35% larger than that of the clean GB. This suggested that the presence of He would hinder the V GB mobility. Based on the thermodynamic criterion, the total energy calculations indicated that the embrittlement of V GB would be enhanced by He segregation. [ABSTRACT FROM AUTHOR]