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 degrees 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 theta-Al2O3 to alpha-Al2O3 at initial oxidation stage. The NiAlDyCr-3 Si alloy yielded a mass gain of similar to 0.64 mg/cm(2) 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. (C) 2013 Elsevier Ltd. All rights reserved.