D2 retention behavior and microstructural evolution of W-2wt.%Y2O3 alloy during He-ion irradiation at high temperatures

In this study, we carried out the pre-irradiation of a dispersion-strengthened W-2wt.%Y2O3 alloy with good mechanical properties with high-energy Fe-ions instead of neutrons. The effect of this pre-irradiation on the D2 retention behavior of the alloy was investigated. A maximum of 1022 D/m2 was irradiated onto the samples using 5-keV D2 ions, and Fe pre-irradiation was carried out up to an ion fluence of 4 × 1018/m2 with 1 MeV energy. For comparison, commercial pure W was also studied. The Fe-ion pre-irradiation process increased the D2 retention in both pure W and the W–Y2O3 alloy. However, this D2 retention was independent of the pre-irradiation dose. In addition, the formation of He bubbles in the W–Y2O3 alloy caused by the irradiation at 1.8 × 1021 He/m2 and high temperatures of 773, 973, and 1173 K was also investigated. When the irradiation dose exceeded 1.5 × 1020 He/m2, visible He bubbles were formed, and He bubbles grew and void swelling increased with an increase in the irradiation dose. Compared to pure W, the W–Y2O3 alloy showed suppressed void swelling. This can be attributed to the dispersion of vacancies and He atoms due to the He irradiation.