Orientation dependence of blister shape in niobium monocrystals implanted with channeled helium ions

Abstract

The shape, size, and orientation of blisters formed on the (111), (110), and (001) surface planes of monocrystalline niobium samples irradiated at 900°C with 0.5-MeV channeled 4He+ ions have been studied. The results indicate a strong dependence of (a) the blister shape and (b) the orientation of the blisters with respect to each other on the crystallographic orientation of the target. Both observations can be related to the intersection of certain active slip planes with the surface plane of the monocrystal during blister formation. This interpretation elucidates our recently reported anomaly in the alignment of the blisters on Nb (111) planes.