镍基高温合金CM247LC水蒸气氧化行为研究

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

摘要:

系统研究了镍基高温合金CM247LC在1100 ℃、不同水蒸气含量下氧化2 h的行为。采用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)和热力学计算对氧化膜的表面和截面形貌、物相组成及形成机理进行了分析。结果表明：水蒸气显著加速CM247LC合金的氧化,水蒸气含量增加导致氧化增重加剧,氧化膜厚度逐渐增加。表面氧化膜从细小均匀的氧化物颗粒演变为粗大颗粒,并逐渐团聚成氧化膜。氧化膜呈现多层结构,主要由NiO、Cr₂O₃、HfO₂、TiTaO₄、CoCr₂O₄和富Al氧化物组成,其形成顺序与各氧化物生成的吉布斯自由能顺序一致。水蒸气促进了氧化物的生长,并引发氧化膜剥落,从而降低合金的抗氧化性能。

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.