The effects of the minor alloying elements Al, Si and Mn on the cyclic oxidation of Ni–Cr–W–Mo alloys

• Effect of Al, Si and Mn on cycling oxidation behaviour of Ni–22Cr–14W–2Mo is studied.
• 0.6 wt% Al addition reduces both spallation and parabolic rate constant.
• 0.8 wt% Si addition reduces parabolic rate constant, but does not enhance adhesion.
• Detrimental effect of Mn addition is effectively suppressed by Si and Al addition.

The effect of the addition of less than 1 wt% of Al, Si and Mn on the cyclic oxidation of the Ni–22Cr–14W–2Mo alloy is investigated. The cyclic oxidation experiment is performed between 1150 °C and 400 °C. Al and Si addition reduced the oxidation rate by suppressing the formation of transient oxides. In particular, Al enhanced the adhesion of the oxide scale by forming oxide pegs and a (Cr,Al)2O3 layer. Mn is detrimental to the oxidation resistance by enhancing the formation of NiO, NiCr2O4, and NiWO4. However, the detrimental effect of Mn is suppressed by the addition of Al and Si.