Theoretical insight into the effects of nitrogen and vacancy defects on the behavior of helium in tungsten

Abstract

The effects of nitrogen (N) on the dissolution, trapping, and diffusion behaviors of helium (He) in tungsten (W) have been investigated using firstprinciples simulations. In the presence of the N atom, the solution energy of the He atom in W is reduced because of the attractive interaction between He and N atoms. However, the dominant force between He and N atoms becomes repulsive with the existing vacancy. During this interaction, the N-V complex can capture five He atoms in W, thereby degrading the ability of the W vacancy to capture He atoms. Furthermore, we find that the He atom can be more easily diffused in the N-V complex than in N-free vacancy.

The Effect of Yttrium on the Solution and Diffusion Behaviors of Helium in Tungsten: First-Principles Simulations

“…In this paper, the micro-evolution behavior of He has been calculated on the 128-atom (4 × 4 × 4) body-centered cubic (bcc) supercell. The Brillouin-zone integration was performed within Monkhorst–Pack [ 32 ] scheme using a 3 × 3 ×3 mesh for the geometry optimizations and 4 × 4 × 4 mesh for electronic calculations in the supercell [ 33 ]. A cutoff energy of 350 eV was set for all simulation calculations.…”