The pre-oxidation treatment was conducted for NiAlHf coatings in a sealed glass tube with low oxygen atmosphere at 900 °C. The microstructure evolution and oxidation resistance of the NiAlHf coatings with and without pre-oxidation treatment were systematically investigated via isothermal oxidation at 1200 °C for up to 200 h in laboratory air. The results revealed that a dense Al₂O₃ scale was formed on the NiAlHf coating surface after pre-oxidation treatment, which could effectively reduce oxygen pressure and Al consumption on the NiAlHf coating surface. Furthermore, the NiAlHf coating microstructure evolution was effectively delayed from β-NiAl to the γ′-Ni₃Al phase due to Al₂O₃ scale formation by pre-oxidation treatment. Oxidation resistance of the NiAlHf coating with pre-oxidation treatment was improved after 200 h of oxidation, of which the oxidation rate constant was enhanced by 40% compared to the NiAlHf coating without pre-oxidation treatment. The mechanism of oxygen diffusion inhibition by pre-oxidation was also discussed. This research was beneficial to understand the effect of pre-treatment on the NiAHf coating microstructure evolution and could further guide the improvement of the oxidation resistance of NiAlHf coatings for long-term oxidation.

NiAlHf 涂层在 900 ℃、低氧气氛的密封玻璃管中进行预氧化处理。通过在实验室空气中在 1200 °C 等温氧化长达 200 小时，系统地研究了经过和未经预氧化处理的 NiAlHf 涂层的微观结构演变和抗氧化性。结果表明，预氧化处理后的NiAlHf涂层表面形成致密的Al ₂ O _{3氧化皮，可有效降低NiAlHf涂层表面的氧压和Al消耗。}此外，由于Al ₂ O ₃ ，NiAlHf涂层的微观组织演变从β-NiAl有效延迟到γ'-Ni _{3 Al相。}通过预氧化处理形成水垢。经预氧化处理的NiAlHf涂层在氧化200 h后的抗氧化性有所提高，与未经预氧化处理的NiAlHf涂层相比，氧化速率常数提高了40%。还讨论了预氧化抑制氧扩散的机理。该研究有利于了解预处理对NiAlHf涂层微观组织演变的影响，并可以进一步指导NiAlHf涂层长期氧化抗氧化性的提高。