On the possibility of severe corrosion of a Ni-W-Cr alloy in fluoride molten salts at high temperature

Abstract The corrosion of a Ni-26W-6Cr alloy, as well as GH3535 alloy, in the FLiNaK salts at 800 °C was investigated by static immersion corrosion, combining with the electrochemical measurements and DFT calculation. Results show Cr-depletion layers with maximum depths of about 13 μm form in the near surface of both alloys, and very slight depletion of W and Mo was observed. The excellent corrosion resistance of Ni-26W-6Cr alloy is due to the immunity of W to FLiNaK salts and the low diffusion coefficient of W. Moreover, W and Mo have negligible effects on the diffusion of Cr outwardly to alloy surface.