The effect of substrate orientation on oxidation-induced void formation in β-Ni–40Al–5Cr–0.03Y

Oxidation of a model β-phase Ni–40Al–5Cr–0.03Y (at.%) was studied in the temperature range 1000–1100 °C. Numerous voids formed at the oxide/alloy interface, and the coalescence of those interfacial voids caused extensive spallation of the thermally grown oxide during isothermal oxidation. The density of interfacial voids depends on the orientation of the bond coat alloy substrate, which suggests that the epitaxial Al2O3/alloy interface structure plays an essential role in the formation of interfacial voids during oxidation.