The stability and migration behavior of helium and self defects in vanadium and V–4Cr–4Ti alloy were studied by first-principles calculation. The tetrahedral site was found as the most stable configuration for interstitial He, followed by the octahedral and substitutional sites. Among the self defects, the monovacancy had lower formation energy (1.71eV for V and 2.14eV for V-4Cr-4Ti alloy) than the self interstitial ones. The migration energies for He hopping between the tetrahedral sites were 0.06 and 0.09eV for vanadium and V-4Cr-4Ti alloy, respectively. The calculations revealed strong repulsion between two interstitial He atoms and strong attraction between He and vacancy, suggesting that the vacancy acted as a trapping site for He impurity and a seed for further bubble formation.

Stability and Migration Property of Helium and Self Defects in Vanadium and V–4Cr–4Ti Alloy by First-Principles. P.Zhang, J.Zhao, Y.Qin, B.Wen: Journal of Nuclear Materials, 2011, 413[2], 90-4