The oxidation behavior of four γ/γ′ Ni-based alloys: without additions, and containing: Hf (1.0 wt%), a combination of Hf and Y (0.3 wt% and 0.03 wt%, respectively), and a combination of Hf and Si (1.0 wt% and 1.0 wt%, respectively) was studied in air under isothermal (50 h) and thermal cycling (up to 2225 1-h cycles) conditions. Samples were characterized using SEM, EDX and XRD techniques. The results indicated that all the additions improved the oxidation resistance of the alloy but only in the case of materials containing the (Hf + Y) combination of additions was a long-term effect achieved. Substantial weight losses were observed on the other unmodified and (Hf + Si)-containing materials during thermal cycling after short exposure periods, while on material containing only additions of Hf, they occurred significantly later. Kinetic studies showed the highest oxidation rate in the case of the (Hf + Si)-containing alloys and the fastest initial oxidation, prior to the parabolic law-obeying stage, of alloy with Hf-additions, only. The results indicate the superior effect of simultaneous application of Hf and Y additions at levels not exceeding their solubility limits and that lowering its effectiveness Hf overdoping (1 wt%) cannot be effectively counteracted by the addition of 1% Si.

四种 γ/γ' Ni 基合金的氧化行为：未添加，且含有：Hf（1.0 wt%）、Hf 和 Y 的组合（分别为 0.3 wt% 和 0.03 wt%）以及 Hf 的组合和 Si（分别为 1.0 wt% 和 1.0 wt%）在等温（50 小时）和热循环（最多 2225 个 1 小时循环）条件下在空气中进行研究。使用 SEM、EDX 和 XRD 技术对样品进行表征。结果表明，所有添加物都提高了合金的抗氧化性，但只有在含有 (Hf + Y) 添加物组合的材料的情况下才能实现长期效果。在短时间暴露后的热循环过程中，在其他未改性和含 (Hf + Si) 的材料上观察到了大量的重量损失，而在仅添加 Hf 的材料上，它们发生的时间要晚得多。动力学研究表明，在含 (Hf + Si) 合金的情况下氧化速率最高，在抛物线服从阶段之前，只有添加 Hf 的合金的初始氧化速度最快。结果表明，同时添加 Hf 和 Y 的效果不超过它们的溶解度极限，并且 Hf 过度掺杂 (1 wt%) 无法通过添加 1% 的 Si 有效抵消其有效性的降低。