The role of Cr and Si in affecting high-temperature oxidation behaviour of minor Dy doped NiAl alloys

Isothermal and cyclic oxidation behaviour of Cr/Si co-doped NiAlDy alloys were investigated at 1200 °C. The role of Cr and Si in oxidation of NiAlDy alloys was discussed by combining experimental results and first-principles calculations. Cr and Si would co-segregate at grain boundaries and promoted the transformation from θ-Al2O3 to α-Al2O3 at initial oxidation stage. The NiAlDyCr-3Si alloy yielded a mass gain of ∼0.64 mg/cm2 after 100 h isothermal oxidation and showed much improved cyclic oxidation resistance due to the pair affinity between Si and Cr which can alleviate the deleterious effect of interfacial Cr precipitation.