Enhanced corrosion of nickel-based alloy in molten chloride salt driven by Ce3 + with low redox potential

It is well established that the oxidizing species with high redox potentials could initiate and significantly accelerate the structural material corrosion in molten salt. However, here we found that the presence of Ce 3+ , an electrochemically less active cation, in LiCl-KCl eutectic molten salt could also enhance alloy corrosion. This effect was demonstrated through the corrosion behavior study of Inconel 600 alloy exposed to LiCl-KCl eutectic melt containing varying concentrations of CeCl 3 at 500 °C under an inert Ar atmosphere. The corrosion behavior study was performed by both the static immersion corrosion tests and electrochemical analyses. As the concentration of CeCl 3 increases from 0.5 wt% to 5 wt% and 10 wt%, the corrosion depth increases from 3.43 μm to 16.00 μm and 18.86 μm, leading to progressively severe wormhole corrosion due to chromium dissolution. The enhanced corrosion mechanism of Inconel 600 alloy was attributed to the formation of CeOCl driven by trace oxygen present in the Ar atmosphere. This study highlights the previously underestimated role of less oxidizing metal species in molten salt corrosion and provides new insights for the future study in molten salt applications.