为了解决第四代镍基单晶高温合金W、Mo含量较高导致高温抗氧化性能下降的问题，本工作深入研究了一种稀土元素复合添加的新型第四代单晶高温合金在1100 ℃下的氧化行为和γ'相退化规律。结果表明，氧化前3 h时，样品表面迅速形成NiO层和不连续针状Al₂O₃层，并在NiO层下方形成一层稀土氧化膜。稀土氧化膜抑制O元素向内扩散与难熔金属元素反应形成尖晶石氧化物，降低尖晶石氧化物层的增厚速率，这有利于第二阶段(3~25 h)不连续针状Al₂O₃层向部分连续Al₂O₃层转变，减缓第三阶段(25~60 h)氧化增重下降阶段的发生。氧化100 h后，合金表面形成连续Al₂O₃层和NiAl₂O₄尖晶石层，有效阻止合金元素向外扩散和O元素向内扩散。此外，无γ'区厚度随着氧化时间的延长逐渐变大，但在无γ'区和合金内部并未发现拓扑密堆(TCP)相，说明合金在高温下具有良好的微观结构稳定性。

To improve the oxidation resistance, which is compromised by high concentrations of W and Mo in control alloys, developing a new fourth-generation Ni-based single crystal superalloy is essential. In this study, we investigated the oxidation behavior and γ' phase degradation of a new fourth-generation single crystal superalloy containing rare earth (RE) elements at 1100 ^oC. After an initial 3 h of oxidation, a NiO layer and a discontinuous, needle-like Al₂O₃ layer rapidly formed on the sample surface, accompanied by the formation of a RE oxide film beneath the NiO layer. The RE oxide film effectively inhibited the internal diffusion of O element and its reaction with refractory metal elements, preventing the formation of spinel oxides and reducing the thickening rate of the spinel oxide layer. As a result, the discontinuous needle-like Al₂O₃ layer transforms into a partially continuous Al₂O₃ layer during the second stage (3-25 h) and delayed oxidation-induced mass loss in the third stage (25-60 h). After 100 h of oxidation, continuous Al₂O₃ and NiAl₂O₄ spinel layers were formed on the alloy surface, effectively hindering both the outward diffusion of alloy elements and the inward diffusion of O element. Moreover, the γ'-free layer exhibited a notable increase in thickness with the oxidation time. No topologically close-packed phase was detected in the γ'-free layer or in the interior of the sample, indicating the superior high-temperature stability of the alloy.