Study on the Steam Oxidation Behavior of Nickel-Based Superalloy CM247LC

Abstract:

A systematic investigation was conducted on the oxidation behavior of nickel-based superalloy CM247LC at 1100 ℃ for 2 h under different water vapor contents. The surface and cross-sectional morphologies, phase composition, and formation mechanism of the oxide scale were analyzed by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and thermodynamic calculations. The results indicate that water vapor significantly accelerates the oxidation of CM247LC alloy. As the water vapor content increases, the oxidation weight gain intensifies and the oxide scale thickness gradually rises. The surface oxide scale evolves from fine and uniform oxide particles into coarse particles, which subsequently agglomerate to form a continuous oxide layer. The oxide scale exhibits a multi-layer structure, primarily composed of NiO、Cr₂O₃、HfO₂、TiTaO₄、CoCr₂O₄ and Al-rich oxides. The formation sequence of these oxides is consistent with the order of their Gibbs free energies of formation. Water vapor promotes the growth of oxides and induces spallation of the oxide scale, thereby deteriorating the oxidation resistance of the alloy.