  Irradiation effects in Ni-17Mo-7Cr alloy, which is an newly developed
structural material for molten salt reactor (MSR), have been systematically
investigated by using 3MeV Au ions at different fluences, corresponding to dpa
number (displacement per atom) of 1~ 30. GIXRD measurement indicates that the
microstrain of the irradiated samples increased from 0.14% to 0.22% as dpa
increased from 1 to 30. In the meanwhile, nanoindentation results reveal the
Ni-17Mo-7Cr alloy underwent radiation-induced hardening first and then
softening at dpa of 30. The swelling rate of Ni-17Mo-7Cr alloy was found around
1.3% at 30 dpa, which means only 0.04% per dpa. Besides, Raman spectra shows
that carbon segregation appeared after Au ions irradiation. Our results are
very helpful for understanding irradiation damages in Nickel-base alloys,
especially for those in purpose of being used in future MSR nuclear energy
system.
