Depth-dependent nanoindentation hardness of reduced-activation ferritic steels after MeV Fe-ion irradiation

The irradiation hardening behavior of F82H reduced-activation ferritic steels after MeV Fe-ion beam irradiation experiments was investigated with a nanoindentation test. Two sets of ion-irradiation experiments were conducted at 270 °C with 10.5 MeV Fe3+ ions up to 5 dpa at a 1000 nm depth at TIARA facility and at 290 °C with 6.4 MeV Fe3+ ions up to 3 dpa at a 600 nm depth at DuET facility, respectively. The measured nanoindentation hardness was converted to the depth-dependent bulk-equivalent hardness based on a combination of the Nix–Gao model to explain the indentation size effect and the film/substrate model to explain the damage gradient effect in the ion-irradiated region and softer substrate effect of the non-irradiated region beyond the irradiated depth range.