Helium migration in Zr-Nb multilayers under electric field

Abstract The α particles, which appear during the nuclear reactions and are transformed into He atoms, are often implanted into (or produced in) the structural materials causing deterioration of the mechanical properties. Moreover, they precipitate into high-pressure He bubbles, further decreasing the strength. Metallic alloys with a high density of interfaces and/or grain boundaries can reduce or even heal the defects caused by irradiation; nevertheless, the detrimental effect of He atoms is still a concern and diffusion of He atoms in the vicinity of interfaces is the subject of active research. Here, we present an ab initio study to explore how the electric field influences the diffusion of He atoms in (HCP-BCC) Zr-Nb metallic multilayer composite before they start to agglomerate. Motivated by our previous work, where we showed that He atoms tend to agglomerate into the regions with low electron density, we utilized the shift of electrons inside Zr-Nb multilayer system due to the external field to manipulate the migration of He atoms in a preferred direction. The results indicate that He atoms can be guided along the direction of the field out of the system, especially along [0002] direction in HCP-Zr.