Hot corrosion behavior of powder metallurgy Rene95 nickel-based superalloy in molten NaCl–Na2SO4 salts

Abstract Hot corrosion behavior of powder metallurgy (PM) Rene95 Ni-based superalloy in molten 25%NaCl + 75%Na 2 SO 4 salts at 650 °C, 700 °C and 750 °C are investigated by weight loss measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Experimental results show that hot corrosion kinetics follow a square power law at 650 °C and linear power laws at 700 °C and 750 °C. The corrosion layers on the surface of PM Rene95 superalloy are detected to be mainly composed of Cr 2 O 3 , NiO, and Ni 3 S 2 at each temperature. Besides, small amounts of NiCr 2 O 4 at 700 °C and NaCl at 750 °C are observed respectively. Cross-sectional morphologies and corresponding elemental maps indicate that corrosion layers near scale/alloy interface are composed of oxides at 650 °C while duplex oxides and sulfides at 700 °C and 750 °C. According to these results, a cooperating mechanism of oxidation and sulfuration for hot corrosion of PM Rene95 Ni-based superalloy is confirmed.

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