Comparison of the Effect of 2 at. % Additions of Nb and Ta on the 1100 °C Oxidation Behavior of Ni-6Al-(4,6,8) Cr Model Alloys

To continue improving alloy performance in harsh service environments, the development of alumina-forming nickel-based superalloysNickel-based superalloy is essential. Current generations of these alloys heavily rely on the addition of refractory elements to enhance their mechanical propertiesMechanical properties at high temperaturesHigh temperature oxidation; however, a systematic understanding of how such additions affect the overall oxidationOxidation behavior is still not well established, particularly from the standpoint of predicting the transition from internal to external alumina formation. The present work seeks to better understand the intrinsic effects that common minor additions of Ta and Nb have on the oxidationOxidation behavior of alumina-scale-forming γ-Ni model alloysModel alloy. By combining a novel simulation approach with high-temperatureHigh temperature oxidationOxidation experiments and advanced characterization techniques, the present study provides insightful details on the differing effects that 2 at. % addition of Ta and Nb have on the alumina scale formation of Ni-based alloysNi-based alloy during 1100 °C oxidationOxidation.