Effect of trace Ce on high-temperature oxidation behavior of an Al–Si-coated Ni-based single crystal superalloy

Ni-based single crystal superalloy IC21 with different Ce contents was prepared by screw selection method, and Al–Si coatings were prepared by pack cementation. Cyclic oxidation and transient oxidation were carried out at 1150 °C to investigate the effect of Ce on the high-temperature oxidation behavior of Al–Si coatings. After cyclic oxidation at 1150 °C, the addition of trace Ce decreased the mass gain of the Al–Si-coated samples and effectively improved oxidation performance and spallation resistance. In specimens without Ce doping, microstructure examination revealed that bulky γ′-Ni ₃ Al precipitated in oxidized coating because of high Al consumption, and this finding suggests that Ce inhibits the consumption of Al in the coating during oxidation. Ce slows down the transformation of θ-Al ₂ O ₃ to α-Al ₂ O ₃ and improves the adhesion of the oxide scale.