Depth distribution of cavities in 20- and 500-KeV4 He+-irradiated nickel
Studies on depth distribution of damage and of cavities (voids and bubbles) in ion irradiated metals are of importance for an understanding of the mechanisms of radiation blistering and are of general interest to the field of radiation damage.The present paper describes transmission electron microscopy results on depth distribution of cavities and of dislocation damage in nickel irradiated at 500°C with 20- and 500-keV 4He+ ions. The results are compared with calculated projected range and damage energy distributions.High purity (99.995%) annealed polycrystalline nickel foils were irradiated at 500°C with either 20- or 500-keV 4He+ ions to total doses of 2.9 x 1016 and 1 x 1017 ions/cm2, respectively. Thin foils suitable for transmission electron microscopy were prepared from the irradiated samples by a transverse sectioning technique described elsewhere, which allows one to obtain depth distribution of damage and of bubbles from a single specimen.Figure 1 shows typical bright field transmission electron micrographs of the plated and irradiated regions of annealed polycrystalline nickel irradiated at 500°C with 500-keV 4He+ ions to a dose of 1 x 1017 ions/cm2.