Effects of Y addition on the pre-oxidation and corrosion behaviours of the alumina/niobium aluminide coatings on the surface of niobium core

Y-modified alumina/niobium aluminide coatings were prepared on the surface of the niobium substrate by pack cementation and subsequent pre-oxidation treatments. The pre-oxidation behaviour of the Y-modified and undoped alumina/niobium aluminide coatings in the air atmosphere at 1300 ℃ and their corrosion behaviour in the molten DZ4125L superalloy at 1500 ℃ were investigated in this study. It was demonstrated that the Y addition could reduce the growth rate of the oxide scale, suppress the localised oxidation failure and improve the molten superalloy corrosion-resistance of the alumina/niobium aluminide coatings. The mechanism of Y modification has also been revealed.