Evaluation of high temperature corrosion resistance of a Ni3Al (Mo) alloy

The sulfidation/oxidation and carburization resistances of a Ni3Al(Mo) (IC-6) alloy at high temperatures were investigated in this work. The corrosion kinetics of the IC-6 alloy was found to follow parabolic rate law in an environment of high partial pressures of sulfur (∼10−5 atm) and low partial pressures of oxygen (<10−20 atm) at 700 °C. Because the Ni sulfides are readily formed at the testing temperature, the sulfidation/oxidation resistance of the IC-6 alloy is similar to that of commercial Ni–Cr alloys in the current environments, although IC-6 is alloyed with Al. Compared with the HP heat resistant steel which is commonly used in the petrochemical industry, the IC-6 alloy possesses significantly improved resistance to carburization at 1100 °C. The mechanisms governing the corrosion attack in the environments used in this investigation were also discussed.