Isothermal oxidation behavior of micro-regions in multiphase Ni3Al-based superalloys

Abstract The isothermal oxidation behavior of micro-regions in multiphase Ni3Al-based superalloys (high Fe and Cr contents) was investigated at 600 °C in air. The oxide scale is mainly composed of the outer mixed oxide layer (NiO, NiFe2O4 and Al2O3) and the inner single Al2O3 layer. In particular, Cr2O3 is formed in the outer oxide scale of γ' + γ dendrite with enrichment in Cr element. The relative dense continuous Al2O3 layer is formed in the interdendritic region (β phase with high Al content). In addition, γ' envelope (connecting the γ' + γ dendrite and interdendritic β phase) shows preferential oxidation featuring significant cellular bulge (NiO and NiFe2O4 mixed oxides).