Effect of annealing on Cu precipitates in H ion irradiated Fe–0.6%Cu studied by positron annihilation

Fe–0.6%Cu alloy was irradiated with H ions to 0.1 dpa, and then annealed for 30 min from 150 °C to 500 °C. We focused the evolution of Cu precipitates in irradiated Fe–0.6%Cu alloy after the isochronal annealing from the perspective of positron annihilation. The ΔW parameters after thermal annealing (400 °C and 500 °C) were much larger than that induced by 0.1 dpa H irradiation. Annealing could promote the aggregation of the Cu-vacancy complexes, and form the Cu cluster–vacancies complexes. When the vacancy-like defects recovered around 500 °C, it meant the formation and growing of the defect-free Cu precipitates. - Graphical abstract: Irradiation can lead to the formation of the Cu–vacancy complexes, and the aggregation of the Cu–vacancy complexes would form the vacancy clusters surrounded by ultrafine Cu precipitates (≤2 nm). The decrease of ΔS means the recovery of vacancy-like defects (Figure a). The obvious increase of the ΔW parameters indicates that the Cu precipitate phenomenon has enhanced (Figure b). Combine the defect complete recovery with the Cu precipitate aggregation, Cu precipitates free from vacancies formed and coarsened at 500 °C. Display Omitted - Highlights: • Irradiation led to the formation of the Cu–vacancy complexes. • Vacancy clusters surrounded by ultrafine Cu precipitates formed. • Mostly of the vacancy-like defects completely recovered by annealing at 500 °C. • Defect-free Cu precipitates formed and coarsened at 500 °C.