Corrosion behaviour in liquid lead of pristine and irradiated FeCrAlNi coatings deposited by HiPIMS

• FeCrAlNi coatings were deposited on 316L stainless steel by HiPIMS. • Plasma pre-treatment improved coating/substrate interface stability. • Adhesion was preserved after thermal and irradiation exposure. • Corrosion resistance was confirmed in pristine and irradiated coatings. FeCrAlNi coatings with controlled morphology, microstructure, composition and adhesion were developed using High Power Impulse Magnetron Sputtering (HiPIMS) to improve the performance and durability of steels exposed to Lead-cooled Fast Reactor (LFR) environments. The protective behaviour and property evolution of the coatings were investigated through corrosion experiments performed at 600 °C for 1000 h on both pristine and ion-irradiated samples. Irradiation was conducted at room temperature and 600 °C to simulate service conditions. Results revealed that thermal exposure, rather than irradiation, played a major role in driving coating modifications, promoting elemental redistribution and increased crystallinity. Notably, the coating/substrate interface remained stable, attributed to a tailored plasma pre-treatment designed to take advantage of the characteristics of the HiPIMS process. Corrosion experiments demonstrated good corrosion resistance and adhesion of both pristine and irradiated FeCrAlNi coatings. In all cases, a protective surface oxide scale formed, whose thickness, composition and crystallinity varied depending on the initial condition of the sample. These findings highlight the robustness of HiPIMS-deposited FeCrAlNi coatings as corrosion barriers and the critical role of pre-treatment in ensuring interface stability under extreme environments.