Hydrogen retention and diffusion in tungsten beryllide.

Beryllide compounds are often used in various domains because they are more resilient to oxidation than pure beryllium and at the same time they keep some of the properties of this metal. Nevertheless, the data about their properties during atomic hydrogen exposure are very scarce: numerous experiments have been conducted in the past few years on solid hydride deposition under beryllium-seeded plasma action or on energetic hydrogen implantation into metallic beryllium; many others have been devoted to hydrogen retention and diffusion in tungsten. There have been fewer studies about hydrogen interaction with the alloys of these metals, although the beryllium-tungsten mixed compounds have been experimentally detected in laboratory experiments. This article reports on calculations carried out using first-principles density functional theory (DFT) on tungsten beryllide crystal (Be12W) taken as a model alloy. The formation and reactivity of atomic vacancies are investigated in the domain of temperature ranging from 0 to 500 K, together with atomic hydrogen retention and diffusivity in the bulk and in/out vacancies.