作为新型轻质耐高温结构材料，TiAl 合金因具有低密度、高比强度、优异的高温抗蠕变性能等优点，是钛合金使用温度上限和高温合金使用温度下限区间内(700~900 ℃)的唯一候选材料。 然而，在 TiAl 合金的实际服役环境中，燃油或海水中的 S、Cl 和碱金属元素的杂质会产生混合盐， 沉积在 TiAl 合金构件表面并与合金基体发生热腐蚀行为，诱导合金构件失效。 因此需要构建高温腐蚀环境，研究 TiAl 合金的热腐蚀行为，为推进 TiAl 合金的服役性能评估与优化提供理论参考。基于此，在 850 ℃盐雾环境下对 TNM 合金的热腐蚀行为展开系统研究，观察其表面形貌，分析热腐蚀产物组成，探讨热腐蚀行为机理。 结果表明，在 850 ℃下 TNM 合金表面热腐蚀产物由鳞片状 TiO2 和连续致密的 Al2O3组成，且最外层以 TiO2 为主，随热腐蚀时间延长，TiO2 形态由鳞片状向柱状转变，分布形式趋于团簇分布。 随热腐蚀时间延长或循环周次增加，热腐蚀层在腐蚀介质侵蚀与热应力耦合作用下发生破碎脱落，暴露出合金基体组织并进一步发生热腐蚀，出现腐蚀层“形成-脱落”的循环过程。 随热腐蚀时间延长，合金表面的热腐蚀行为由热腐蚀层“形成-脱落”的循环过程转变为沿 α2 相快速向合金内部侵蚀的相选择性腐蚀过程，导致表面难以形成连续保护性氧化层，严重破坏合金的抗腐蚀性能。

As a new type of lightweight high-temperature resistant structural material, owing to its advantages of low density, high specific strength, and excellent high-temperature creep resistance, TiAl alloys stand as the sole candidate material within the temperature range between the upper service temperature limit of titanium alloys and the lower service temperature limit of superalloys (from 700 to 900 ℃ ). However, in the actual service environment of TiAl alloys, impurities such as S, Cl, and alkali metal elements from fuel or seawater can form mixed salts. These salts deposit on the surface of the TiAl alloy components, inducing hot corrosion reactions with the alloy matrix, which leads to component failure. Thus, it is necessary to construct a high-temperature corrosion environment to investigate the hot corrosion behavior of TiAl alloys, which will provide theoretical references for advancing the evaluation and optimization of their service performance. Accordingly, a systematic study on the hot corrosion behavior of TNM alloys was conducted under 850 ℃ salt spray conditions. The surface morphology was observed, the composition of the hot corrosion products was analysed, and the mechanism of hot corrosion behavior was discussed. The results indicate that the hot corrosion products on the surface of TNM alloys are dominated by flake-like TiO2 and a continuous dense Al2O3 layer at 850 ℃,and the outermost layer is dominated by TiO2.As hot corrosion continues, the morphology of TiO2 transforms from flake-like to columnar, and its distribution tends to be clustered. With increasing hot corrosion time or an increase in the number of hot corrosion cycles, the hot corrosion layer fractures and spalls under the coupling effect of corrosive medium erosion and thermal stress, which exposes the alloy matrix and leads to further hot corrosion, resulting in a cyclic process of "formation to spallation" of the hot corrosion layer. As the hot corrosion time increases, the hot corrosion behavior on the alloy surface transitions from the cyclic process of "formation-spallation" of the corrosion layer to a phase-selective corrosion process that rapidly penetrates the alloy interior along the α2 phase. This transition makes it difficult to form a continuous protective oxide layer on the surface, which severely deteriorates the corrosion resistance of the alloy.