The microstructure of nickel-base alloy C-276 irradiated at 500℃ with 300 keV self-ions (Ni + ) to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of (8.2±0.2)×10 15 cm-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. In [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly (a/2)<110>. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures. The microstructure of nickel-base alloy C-276 irradiated at 500 ° C with 300 keV self-ions (Ni +) to a peak displacement damage of 4.5 displacements per atom was investigated by transmission electron microscopy. Both black spots and dislocation loops were observed. The black spots were identified as small dislocation loops, with a density of (8.2 ± 0.2) × 10 15 cm-3 and the average loop size of about 15 nm. An increase of dislocation loop density would lead to the increase of the hardness in C-276 alloy, and the increment in yield strength was estimated by the dispersed barrier-hardening model. [110] orientation, Burgers vectors of the dislocation loops were determined, and it was found that they were predominantly (a / 2) < 110>. In contrast to other nickel-base alloys, no voids were observed in C-276 alloy after being irradiated at elevated temperatures.