Void formation in some nickel--aluminum alloys during 20-MeV C++ and 46.5 MeV Ni6+ irradiation

The damage intensity along the ions track during 46.5-MeV Ni6+ irradiations of nickel and nickel-based alloys at void formation temperatures has been calibrated. Swelling versus depth profiles were determined in several nickel foils bombarded to a range of doses with 46.5 MeV Ni6+ at 525 C (977 F). A comparison of these results with previous data on swelling in nickel after 20 MeV C++ irradiation at this temperature was made to calibrate the Ni6+ irradiations. Void formation in three nickel-aluminum alloys, at 525 C (977 F), to doses up to 60 dpa has been studied. The alloys contained 6, 8.5, and 13.5 atomic percent aluminum respectively and all specimens also contained [10−5] injected helium. They were bombarded with 20 MeV C++ and 46.5 MeV Ni6+. The 'incubation' dose for void formation, compared with that for pure nickel, was increased. The void concentration decreased with increasing aluminum content in solution and the presence of Ni3Al (γ) precipitates in the third alloy had little effect on the swelling characteristics. The observations have been interpreted in terms of an interaction between the aluminum in solution and the injected helium which starves many potential void nuclei of gas.