Synergistic Effects of Displacement Damage and Helium on Microstructural Evolution and Radiation-Induced Hardening of Reduced Activation Ferritic/Martensitic Steel

Reduced activation ferritic/martensitic steels (RAFs) are leading candidates for blanket and first wall of fusion reactors where effects of displacement damage and helium production are important subjects to be investigated. To obtain systematic and accurate information of microstructural response under fusion environment, dual-ion irradiation method was applied. In order to estimate the microstructural response under fusion neutron irradiation environment, ion-beam irradiation was carried out with helium and metallic self ions. The study is focused on JLF-1 single- and dial-ion irradiated up to 60 dpa at 693, 743 and 793 K. The damage rate and helium injection rate were 1.0 × 10^-3 dpa/sec and 15 × 10^-3 appm He/sec. At 743 K, void cavity structure was observed under dual-ion irradiation where the contribution of void structure on hardening was not so significant. Irradiation hardening and swelling were depended for the case of dual-ion irradiation. It is attempted to quantitatively relate the dislocation and cavities to the irradiation induced hardening.