Hardening of high-energy self-ion irradiated FeCrAl ODS alloys evaluated by micro- and nano-hardness tests

Abstract Hardening of two kinds of FeCrAl ODS alloys irradiated by high-energy heavy ions to about 0.8 dpa at nominal 200 °C is investigated. A damage layer of 24 μm in thickness produced by the ion irradiation in the specimens makes possible both the micro- and the nano-hardness tests. Nix-Gao model is used to eliminate the indentation size effect (ISE) from the hardness data of the damage plateau so as to obtain the equivalent bulk hardness values. Results of the hardness tests show that the FeCrAl ODS alloy with 0.8 wt% Hf addition exhibits better resistance to irradiation hardening than that with 0.6 wt% Zr addition. A correlation between the micro- and the nano-hardness data is established as H V 0 = 74.5 H 0 (HV0 in unit of kgf/mm2, H0 in unit of GPa) for the ODS alloys. A modified Nix-Gao model which includes a maximum allowable density of the geometrically necessary dislocation (GND) and a non-uniform distribution of GNDs can fit well the nano-hardness data in the entire indentation depth range, including the near surface region with a damage ramp.