Recent results for the ferritics isotopic tailoring (FIST) experiment

An alloy of F82H prepared using the isotope 54Fe in order to encourage H and He production in a fission reactor has been irradiated in the HFIR JP20 experiment at three temperatures to 7 dpa as TEM disks. Irradiated disks were shear punch tested, examined by TEM, analyzed for He and H content, and compared with previous results in order to quantify irradiation hardening due to transmutation-induced H and He. Hardening due to irradiation is found following irradiation at 300 and 400 °C, that is intermediate between that at lower and higher dose, but hardening is negligible following irradiation at 500 °C. Microstructural examinations show typical behavior of irradiation as a function of irradiation temperature, with moderate swelling after 400 °C irradiation but few bubbles after irradiation at 300 °C. Correlations of change in hardening with He and H content show little indication of transmutation-induced hardening, but measured H levels do not agree with predictions and therefore H production and analysis requires further study.