Helium retention and diffusion in molybdenum was studied on an atomistic scale with ab initio methods. The thermal stability of helium–vacancy clusters was quantified within the framework of density functional theory. Calculated helium emission rates were used to derive a desorption spectrum which was compared with experimental results. The agreement between the current calculations and available experiments was satisfactory except in the high temperature end of the spectrum. The current results indicate that above 1100K He migration was assisted by lattice defects such as vacancies, rather than through interstitial diffusion.

Helium Cluster Dissolution in Molybdenum. O.Runevall, N.Sandberg: Journal of Physics - Condensed Matter, 2009, 21[33], 335401