Bubbles and precipitates formation and effects on the hardening of irradiated vanadium alloys

Abstract This paper investigated the formation of bubbles and precipitates and the hardening effects in V–4Cr–4Ti alloy after irradiation of He and H ions and post-irradiation annealing. Microstructures observation shows that small bubbles formed in as-irradiated samples, and, during the post-irradiation annealing, lath-like precipitates formed and small bubbles grew upon. It was found that bubbles surrounding precipitates were significantly smaller than those away from, and tended to align along the precipitates. Composition analysis shows that the precipitates comprised TiO with FCC structure. The effects of bubbles and precipitates on hardening were evaluated by the nanoindentation test, as well as the dispersed barrier model that explicitly considered the small bubbles in as-irradiated sample, large bubbles and TiO precipitates in post-irradiated annealed samples. Compared with the as-irradiated samples, the higher hardness in post-irradiated annealed samples is attributed to the co-existence of bubbles and precipitates.