Behaviors of helium in vanadiu m: Stabil ity, diffusi on, vacancy trapping and ideal tensi le strength

The behaviors of helium in vanadium including stability, diffusion, and its interaction with vacancy as well as its effects on the ideal tensile strength was investigated by a first-principles method. The activation energy barrier of helium was calculated to be 0.09 eV, which is consistent with the experimental result. The results indicated that the vacancy can lead to a directed helium segregation into the vacancy to form a helium cluster since the vacancy provides a “lower atomic and electron density region” as a large driving force for helium binding. It is easy for a mono-vacancy to trap helium and form a He_nV complex. The first-principles computational tensile test demonstrates that helium obviously decreased the tensile strength of vanadium.