Irradiation-induced hexagonal precipitates and their coupling with the evolution of helium bubbles

The nature of irradiation-induced precipitates and their interaction with helium bubbles in a nickel-based Hastelloy N alloy were investigated using helium and subsequent xenon ions irradiation at 650 °C. The irradiation by xenon ions has induced the formation of precipitates which were identified as the Mo-Cr enriched M2C-type carbides with a hexagonal close-packed structure. The different behaviors of helium bubbles inside and outside of the precipitates were quantified by bubble size and density. The coupling mechanism between the bubble evolution and precipitate growth under irradiation-induced cascades was unveiled. This work will benefit a further quantitative model describing the interaction between the helium bubbles and growing precipitates under irradiation.