Helium diffusion and bubble evolution in single-phase tungsten-based W-Ta-Cr-V complex concentrated alloy

Tungsten-based complex concentrated alloy (CCA) W-Ta-Cr-V films with bcc single-phase have been investigated for its exceptional radiation tolerance. This work aims to investigate the formation of helium (He) bubble and He retention behavior in the CCA film under 100 eV He plasma at a fluence of 2.02 × 10²⁵ He/m². The results show that the size of He bubbles in the CCA film is smaller than that in the pure W film, and the depth distribution is shallower, which indicates that the evolution of He bubbles is inhibited. As for the underlying mechanism of resistance to the formation of He bubbles in CCAs, it is believed that the characteristic of low He mobility reduces the diffusion depth of He, and the sluggish diffusion of He inhibits the aggregation of He atoms or He clusters to a certain extent. In other words, the unique energy and microstructure characteristics also inhibit the diffusion of He in the CCA film, which affects the nucleation and growth of He bubbles. Furthermore, the release of He is mainly from He adsorption of the near surface, and the desorption peaks shift to lower temperatures in the CCA film within the desorption temperature of 1273 K.