Swelling in Ni-Pr alloys under heavy ion irradiation

The effect of Pr alloying additions on evolutions of defect structures in Ni-Pr alloys (0.07, 0.13, 0.2, 0.4 wt.% Pr) irradiated with 2.8 Mev Ni2+ ions to the doses of 20 to 120 dpa at 600 deg C is studied by transmission electron microscopy. The concentration dependence of Ni-Pr alloy swelling at 40 dpa and the dose dependence of swelling in Ni - 0.2 wt.% Pr and Ni - 0.4 wt.% Pr alloys are obtained. It is shown that increased Pr concentration results in a notable decrease in swelling owing mainly to the continuously decreasing void radius, whereas the void density exhibits maximum at 0.2 wt.% Pr concentration. Complex dependence of the void density on the alloying addition concentration suggests that in the concentration range of 0.13 to 0.2 wt.% the mechanism of the Pr effect on swelling is changing. The authors propose possible mechanisms of high-dose swelling suppression by alloying additions