Hot corrosion behavior of ni-base superalloys in a lithium molten salt

The electrolytic reduction of a spent oxide fuel involves the liberation of the oxygen in a molten LiCl electrolyte, which is a chemically aggressive environment that is too corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the process equipments such as the electroreducer and the salt purification vessel in the pyrochemical process. In this study, the corrosion behaviors of superalloys N-1, N-2 and N-3 in a molten LiCl-Li₂O salt under an oxidizing atmosphere were investigated at 650 °C for 72 h to 216 h. Superalloy N-1 showed the highest corrosion resistance among the examined alloys. The corrosion products of superalloys N-1 and N-2 were NiO, Cr₂O₃, and NiCr₂O₄, while NiO, Cr₂O₃, LiAl₂Cr₃O₈ were identified as the corrosion products of superalloy N-3. For superalloy N-1, its outer corrosion layer was more continuous, dense and adherent compared to those of N-2 and N-3.