Evaluation of hardening behaviors in ion-irradiated Fe–9Cr and Fe–20Cr alloys by nanoindentation technique

The ion irradiation hardening behaviors of Fee9 wt% Cr and Fee20 wt% Cr model alloys were investigated by nanoindentation technique. The specimens were irradiated with 3 MeV Fe11þ ions at room temperature up to 1 and 5 dpa for Fee9Cr alloy and 1 and 2.5 for Fee20Cr alloy. The ratio of average hardness in the same depth of irradiated and unirradiated (Hirr. av/Hunirr. av) was used to determine the critical indentation depth hcrit to eliminate the softer substrate effect. The NixeGao model was used to explain the indentation size effect. Irradiation hardening is clearly observed in both Fee9Cr alloy and Fe e20Cr alloy after ion irradiation. The differences of ISE and irradiation hardening behaviors between Fe e9Cr and Fee20Cr alloys are considered to be due to their different microstructures and microstructural evolution under ion irradiation.