Effects of reactive element oxides on the isothermal oxidation of β-NiAl coatings fabricated by spark plasma sintering

The CeO2, Y2O3 and HfO2 doped β-NiAl coatings with controlled concentrations were fabricated on Hastelloy substrates using spark plasma sintering. The effects of reactive element oxide (REO) species and concentrations on the isothermal oxidation of the β-NiAl coatings were investigated. It was found that the addition of Y2O3 and HfO2 improved the oxidation performance of β-NiAl coatings, but CeO2 with high concentrations (0.5 at.%) had a detrimental effect. At low concentration (0.05 at.% and 0.1 at.%), HfO2 was less effective in improving the oxidation resistance of β-NiAl compared with Y2O3 and CeO2, while HfO2 at higher concentration of 0.5 at.% was the most effective among the three. The effects of REO species and concentrations on the NiAl oxidation behavior were further discussed in related to the intrinsic properties of the REOs and the chemical compositions of the substrate.