Contribution of Y2O3/Hf co-doping to alumina scale growth on oxide dispersion strengthened Co-based superalloy

Abstract

Effect of Y2O3/Hf co-doping on the growth of the alumina scale formed on an oxide dispersion strengthened (ODS) Co-10Ni-20Cr-15Al (at%) superalloy at 900 °C in air was investigated. On both superalloys with and without Y2O3/Hf co-doping, a distinctive layered alumina scale consisting of an outer θ-alumina and an inner α-alumina was formed. Y2O3/Hf co-doping could reduce the oxidation growth rate of the θ- and α-alumina layers and improve the spallation resistance of the scale by suppressing the formation of interfacial pores. The reactive element effect in the θ-alumina has been initially elucidated in detail with the aid of 3D-AP characterization.