Structural Suppression of Blister Formation on the Tungsten Surface under He Implantation with an Energy of 30 keV

The influence of ultrafine-grained structure and cone-shaped surface morphology on the formation of blisters under irradiation of tungsten with He ions with energy of 30 keV has been studied. In comparative experiments, ultrafine-grained and fine-grained samples with an average grain size of 300 nm and 7 μm, respectively, with smooth and cone-shaped surface morphology were used. The ultrafine-grained structure in tungsten samples was obtained by severe plastic deformation, and the cone-shaped surface morphology was obtained by high-fluence irradiation with Ar ions with the energy of 30 keV. It was found that blisters are formed on both fine-grained and ultrafine-grained samples when irradiated with He ions with a fluence of 10 ion/cm. On the fine-grained samples, some of the blisters were with the lids removed, while in the ultrafine-grained samples, all blisters were intact. The thickness of the lids, diameter of the blisters depends on the grain size. The cone-shaped surface morphology on ultrafine-grained tungsten was found to suppress blister formation.