Nanoindentation of ion-irradiated FeCr alloys

Ferritic/martensitic high-chromium steels are candidate structural materials for future nuclear applications for reasons such as resistance to swelling, irradiation creep and oxidation but suffer hardening and embrittlement due to neutron irradiation. Ion irradiation has been proven to be a useful tool to simulate neutron irradiation effects without the drawbacks of producing radioactive material and being restricted to time consuming and expensive in-reactor irradiations. In the present work ion-irradiation in combination with nanoindentation has been applied to study the irradiation-induced hardening of binary Fe-Cr alloys and 9% Cr steels. The details of the approach are specified and the effects of Cr content and irradiation conditions including both single-beam and dual-beam irradiations are considered. Transmission electron microscopy is used to characterize irradiation-induced defects. Ion-irradiation-induced hardening is compared to hardening observed after neutron irradiation at similar conditions and dominant hardening mechanisms are identified in terms of obstacle strength.