Improved irradiation tolerance of W thin films with homogeneously multilayered structure

We report an improved irradiation tolerance of W films by utilizing homogeneously multilayered (HM) structure design. The HM-W film was fabricated by multi-step sputtering, in which the grain boundary density λ could be increased by decreasing the individual layer thickness Pm of the film. The HM structure can improve the film irradiation resistance, in which both He bubble density ρ and average size δ continuously decreased with decreasing Pm. Meanwhile, the irradiation hardening was alleviated by decreasing Pm, while the irradiation-induced phase transition was insensitive to Pm. Our study could provide a promising way to modify the structures of thin films to promote their irradiation resistance.