Inhibition of Ti-rich precipitates and improvement of the irradiation resistance in V-4Cr-4Ti by adding La element

Four kinds of V-4Cr-4Ti-xLa (nominal composition x = 0, 0.1, 0.5, 1.0 wt.%) alloys with different La contents were prepared by vacuum arc melting. Three of them (x = 0, 0.1, 1.0 wt.%) were selected for single He+ (2000 appm for peak concentration) irradiation and sequential He+/V2+ (10 dpa for peak damage) irradiation at 550 C. The results showed that the addition of La element could refine the grains by forming the second phase La2O3 particles. Moreover, the addition of La element reduced the sum of impurity elements concentration in the alloy, which inhibited the formation of Ti-rich precipitates and affected the vacancy concentration, thus affecting the evolution of He bubbles under different irradiation types. In addition, the V-4Cr-4Ti-1.0La alloy had a lower irradiation hardening after sequential He+/V(2+ )irradiation, which might be related to the removal of impurity elements. This work provided a reference for the performance optimization of vanadium alloy for fusion reactors.