LAUSR

Abstract As a solar energy storage medium or heat transfer medium at moderate-high temperature, the molten NaCl-MgCl2 has the advantages of high stability and low cost. But a pipe and container material with Cr will be corroded badly in a molten chloride. Based on the founded corrosion resistance phase (Fe0.64Ni0.36) in previous experiments, the corrosion behavior of a new alloy of Fe-37 wt% Ni with rare earth alloy element Sc in the molten eutectic NaCl-MgCl2 at 520 °C was studied. The corrosion rate of the Fe-37 wt% Ni alloy is lower than that of the researched Fe-based superalloys (GH1035 and GH1140). After corrosion for 15 h, a porous structure with Ni-rich and Fe-depletion is formed at the local location on the Fe-37 wt% Ni surface. For the specimens with Sc (0.3 and 0.5 wt %), a compact protective MgO layer covers on the porous structure, which prevents further corrosion in the molten salt. It is speculated that the Sc is oxidized to Sc2O3 directly or by the chlorination-oxidation reactions, which improves the adhesion strength between the MgO layer and the alloy matrix by the effects of inhomogeneous nucleation and pinning.