Atomistic simulations of defect clustering evolution in heavily irradiated Ti35 alloy

Ti35 alloy (Ti-6wt.%Ta) has greatly promising applications in nuclear industries due to its excellent overall performance. Nevertheless, atomistic mechanisms of its defect clustering evolution due to long-term exposure to irradiation remain scarcely understood by far. Here we investigate the heavy irradiation damage in Ti35 alloy with a dose of up to 4.0 canonical displacement per atom (cDPA) using atomistic simulations of Frenkel pair accumulation. Results show that defect clustering becomes remarkable before 0.04 cDPA and thereafter tends to be relatively stable, and the fraction is not directly dependent on the irradiation dose. Interstitials exhibit a stronger ability than vacancies to form clusters and especially the N_int>5 clusters may cause the formation of 1/3<1‾210> dislocation loops. Compared to the matrix, N_int≤5 interstitial-type defects show a depletion of Ta atoms, while N_int>5 clusters are Ta-rich. This study provides an important insight into the understanding of the irradiation damage behaviors for Ti35 alloy.