Corrosion‐Resistant Ternary Carbides For Use in Heavy Liquid Metal Coolants

A primary concern in the development of accelerator-driven systems (ADS) with liquid leadbismuth eutectic (LBE) spallation target and Gen-IV lead-cooled fast reactors (LFRs) is the compatibility of the candidate structural steels with the heavy liquid metal (HLM) coolant In the accelerator-driven system MYRRHA, the envisaged primary coolant is liquid LBE, a potentially corrosive environment for various nuclear grade steels. The inherent LBE corrosiveness is the driving force behind diverse research incentives aiming at the development of corrosion-resistant materials for specific applications. I3ue to their superb corrosion resistance in contact with liquid LBE, MAX phases are currently being assessed as candidate materials for the construction of pump impellers suitable for MYRRHA and Gen-IV LFRs. In the case of the MYRRHA nuclear system, the pump impeller will be called to operate reliably at ∼270°C in contact with moderately-oxygenated (concentration of dissolved oxygen: [O] ≥ 7×10^-7 mass%), fast-flowing LBE (LBE flow velocity: v ≈ 10-20 m/s locally on the impeller surface). Selected MAX phases are currently being screened with respect to their capability of meeting the targeted material property requirements, especially the enhanced erosion resistance requested by this particular application. This work gives a state-of-the-art overview of the processing and characterisation of selected MAX phases that are screened as candidate structural materials for the MYRRHA pump impeller. All considered MAX phases were produced via a powder metallurgical route and their performance was assessed by various mechanical tests in air/vacuum and corrosion/erosion tests in liquid LBE.