Nanoindentation Study on Depth-Dependent Hardness and Embrittlement of He Ion-Irradiated Fe-9Cr Alloy

This study investigates the effects of neutron irradiation and high-temperature environments on the embrittlement and ductility of ARAA steel, a structural material for fusion reactors, using nanoindentation techniques. Neutron irradiation in fusion environments causes material brittleness, increasing the risk of cracks and compromising reactor safety. Conversely, high temperatures enhance ductility, potentially offsetting embrittlement. This research employs nanoindentation techniques to analyze embrittlement and softening, using He ion irradiation under temperature controls to simulate neutron effects, enabling faster damage assessment and providing insights into material behavior. The results demonstrate that irradiation significantly increases hardness, particularly at shallow depths, while higher temperatures generally reduce hardness across the full depth. Under combined irradiation dose and temperature conditions, He ion irradiation primarily caused embrittlement, but the softening effect from higher temperatures reduced damage depth. Embrittlement was deepest at room temperature and decreased with rising irradiation temperature, with the predicted embrittlement depth limited to 3.0 mu m under combined conditions.