An electron stereomicroscopy analysis of voids produced in nickel during ion irradiation

The spatial distribution of voids produced in nickel during ion irradiation has been investigated by means of transmission electron stereomicroscopy. For 100 keV Ni++ ions, the penetration depth in nickel was calculated to be about 280 Å. At the irradiated surface, there exists a denuded zone of ∼ 300 Å, followed by a void zone of ∼400 Å. Hence the void zone extends well beyond the penetration depth. The present results imply that the nucleation mechanism based on displacement spikes is probably ineffective and that the irradiation could exert an appreciable heating effect in the void zone.