Improved hot-corrosion resistance of Si/Cr co-doped NiAlDy alloy in simulative sea-based engine environment

Hot-corrosion behaviour of NiAlDy, NiAlDyCr and NiAlDyCrSi alloys was investigated at 950°C in a simulative sea-based engine environment. Si and Cr would co-segregate at grain boundaries to form some compounds mainly comprising Cr₅Si₃ for NiAlDyCrSi alloys. After corrosion, compared to the NiAlDy alloy, single doping of Cr was susceptible to the attack caused by large amounts of chlorides in this simulative environment and thus accelerated the scale spallation. While the Si/Cr co-doped NiAlDy alloys exhibited lower oxidation rate and fewer spinels, mainly due to the formation of a thin inert SiO₂ film on the scale.