Insights into hardening, plastically deformed zone and geometrically necessary dislocations of two ion-irradiated FeCrAl(Zr)-ODS ferritic steels: A combined experimental and simulation study

As one of promising candidate materials for fuel claddings and structural components in the Gen-IV fission reactors, FeCrAl(Zr)-ODS ferritic steels were studied to well understand radiation hardening behavior. Nanoindentation (NI) hardness plastically deformed zone (PDZ), geometrically necessary dislocations (GNDs) as microstructures investigated two irradiated with 6.4 MeV Fe3+ at room temperature (RT) up nominal damages 2, 10 50 dpa. Irradiation-induced hardening, which was estimated by using Nix-Gao model regardless damage gradient effect (DGE), increased continuously increasing displacement damage. When taking DGE into account, dependence irradiation (in MPa) on a local level (dpa) obtained finite element method (FEM) simulations 153.65 × (dpa)0.26 158.35 (dpa)0.25 non-Zr steel Zr-added one, respectively. The caused ion-irradiation discussed terms loss oxide particles, formation dislocation loops solid solution mainly dissolved oxygen. addition Zr reduced some extent suppressing loops. Meantime, FEM revealed, PDZ size underneath conical indenter equivalent plastic strain ?eq > 1.9% can reasonably estimate density GNDs. According plasticity (SGP) theory, densities GNDs an indentation depth 200 – 300 nm slightly higher case dpa/nominal than unirradiated, spite similarity steels.