Studies have been made on the void swelling of solution-annealed Fe-15
Cr-20Ni alloy irradiated with 180 keV protons at temperatures from 723
K to 923 K. The displacement damage levels were 5; 10 and 20 dpa for
samples preinjected with 10 appm He at room temperature, and 5 dpa for
samples without He. In comparison with previously reported results of
nickel-ion bombardment, void nucleation seemed to finish at earlier s
tage of irradiation in samples injected with He. Subsequent void growt
h was rather fast and, as a consequence, relatively large swelling was
observed. Void microstructure and swelling were similar at 723 and 77
3 K between the samples with and without preinjected He, but they were
quite different at 823 K probably due to helium effect which persists
even at high temperatures. The results suggest that hydrogen introduc
ed into the material by proton irradiation may play a significant role
, which is similar and comparable to that of helium, in the microstruc
ture evolution during irradiation at temperatures up to 773 K.