• Bubble sizes are similar after single He irradiation in both Cu-Al 2 O 3 and Cu-Y 2 O 3 . • Proportion of dislocation loops is lower in Cu-Y 2 O 3 than Cu-Al 2 O 3 . • Burgers vectors of large loops are not uniformly distributed. This study systematically investigates the microstructural evolution of two kinds of oxide dispersion strengthened (ODS) copper alloys, Cu-Al 2 O 3 and Cu-Y 2 O 3 , under sequential He + /D + ion irradiation. Sequential irradiations were performed using 180 keV He + ions at room temperature and 110 keV D + ions at 300 °C, each to a fluence of 1.0 × 10 17 ions/cm 2 . The microstructures before and after irradiation were characterized by transmission electron microscopy (TEM). The results indicate that the average bubble sizes are similar after single He + irradiation and bubble size increases slightly after sequential He + /D + irradiation. This size increasement in Cu-Y 2 O 3 is larger. The size distribution of irradiation-induced dislocation loops was analyzed under g = (200) and g = (111) two beam conditions. The dislocation size distributions are similar after single He + irradiation, and it shifts towards larger side under g = (111) image in single D + and sequential He + /D + ion irradiated Cu-Y 2 O 3 samples. The Burgers vectors of dislocation loops are uniformly distributed among equivalent crystallographic directions in all Cu-Al 2 O 3 sample and single He + irradiated Cu-Y 2 O 3 sample. The large dislocation loops in single D + and sequential He + /D + ion irradiated Cu-Y 2 O 3 samples are mainly b = 1/2 type and the Burgers vectors of these loops are not uniformly distributed in equivalent crystallographic directions due to the effect of image force from free surface. Besides, the proportion of type dislocation loops is lower in the Cu-Y 2 O 3 samples compared to the Cu-Al 2 O 3 , due to the high frequency of Σ3 boundaries in Cu-Y 2 O 3 , which reduced the sink strength of grain boundary.
Zhang et al. (Fri,) studied this question.