Effects of alloying elements on the corrosion behavior of Ni-based alloys in molten NaCl-KCl-MgCl(2 )salt at different temperatures

The effects of alloying elements on corrosion of Ni-based alloys in NaCl-KCl-MgCl2 under Ar in the temperature range of 600 similar to 800 degrees C were investigated by immersion test, SEM/EDS, EPMA and XRD techniques. A thermodynamic potential-pO(2-) diagram for Cr, Ni at 700 degrees C was constructed. The alloy corrosion is attributed to the dissolution of Cr to form Cr chlorides into salt. The elements Cr, Mo and W can affect the alloy corrosion. The corrosion is accelerated and the intergranular corrosion becomes more pronounced with temperature. Furthermore, the effects of the alloying elements on corrosion have a strong temperature dependence. The related mechanisms are discussed.