Quantum modeling (DFT) and experimental investigation of beryllium-tungsten alloy formation.

Beryllium, tungsten and carbon are planned as wall-cladding materials for the future international tokamak ITER. Be and W will be the dominant components and therefore the formation of binary Be-W alloys under plasma action is one of the most important issues in plasma-wall interaction processes at the first wall. This paper proposes a first-principles density functional theory (DFT) study of beryllium atom retention in tungsten, and a discussion of the results in relation to the available experimental data. In a first step, the beryllium adsorption energy is calculated on the W(100) and W(111) surfaces. Further, the activation barrier for the surface-subsurface diffusion step and subsequent bulk diffusion steps are considered. For each calculation, the electronic structure of the formed compound is analyzed through projected density of states (DOS) calculations.