Pure samples were bombarded with 5MeV Cu ions (single beam) and ions plus H and He gas atoms (dual-beam) simultaneously at 300 to 500C. The ions were stopped a few μm below the surface, and damage formed to that depth. The damage structure was studied as a function of depth by using a focussed ion beam. It was found that, below 300C, bombardment using a single beam produced a high density of stacking-fault tetrahedra, but voids were not observed. Large voids were observed after single-beam bombardment at 500C. In specimens which were bombarded with a dual beam of He and Ni ions, the number-density of voids increased significantly. The number-density of voids was not so high in samples which were bombarded with H and Ni ions. The results showed that He atoms promoted void formation, while H atoms had less effect upon void formation than did He atoms.

Microstructure in Pure Copper Irradiated by Simultaneous Multi-Ion Beams of Hydrogen, Helium and Self-Ions. I.Mukouda, Y.Shimomura, T.Iiyama, Y.Harada, Y.Katano, T.Nakazawa, D.Yamaki, K.Noda: Journal of Nuclear Materials, 2000, 283-287, 302-5