TiAl合金的比强度高、耐高温氧化性能优良，有望在航空发动机中用作高压压气机叶片材料。航空发动机工作时的叶片离心力和系统振动使叶片的榫头位置发生高温微动磨损。本文在国家科技重大专项的支持下，对TiAl合金及防护涂层的高温微动磨损行为与机理进行了研究。针对航空发动机高压压气机叶片榫头的微动工况，对TiAl合金在550 ℃时的微动磨损行为及机理进行了研究。结果表明，微动磨损初期TiAl合金发生剧烈的粘着磨损、剥落和磨粒磨损，导致摩擦系数波动较大、磨损率较高。一定微动循环次数后，磨屑发生压实和摩擦烧结形成摩擦层。摩擦层的纳米晶粒结构和金属氧化物相使其具有高的硬度、H/E和耐磨损性能，并使得TiAl合金的磨损率减小。研究了不同MCrAlY防护涂层的高温微动摩擦磨损行为及机理。其中CoCrAlYSi防护涂层在550 ℃微动磨损中发生剥落、磨粒磨损，且向对偶件的粘着转移严重。CoCrAlYSi防护涂层摩擦氧化产生大量的自扩散系数较低的氧化物，导致形成的摩擦层结构不致密、存在较多孔洞缺陷并发生严重剥落。磨斑内摩擦层的覆盖面积较小，大面积的CoCrAlYSi直接与对偶件接触而发生磨损，导致CoCrAlYSi防护涂层的摩擦系数和磨损率均较高。NiCoCrAlY防护涂层摩擦氧化产生的自扩散系数较低的氧化物较少，形成的摩擦层结构致密、孔洞缺陷较少，在高温微动中剥落破坏轻微。NiCoCrAlY形成的摩擦层磨损轻微，并在磨斑内大面积覆盖，减小了NiCoCrAlY的磨损并抑制了其向对偶件的粘着转移，使得NiCoCrAlY防护涂层的摩擦系数和磨损率均较低。研究了添加Ta元素对防护涂层高温微动磨损的影响。Ta的固溶强化效应提高了防护涂层的纳米硬度和弹性模量。Ta及其在摩擦过程中形成的氧化物对摩擦层起到了固溶和弥散强化效应。Ta对防护涂层和摩擦层的强化作用，使得NiCoCrAlYTa防护涂层的磨损率较NiCoCrAlY防护涂层进一步减小。研究了hBN对NiCoCrAlYTa防护涂层的影响，结果表明hBN可以减小防护涂层的摩擦系数，但增加了防护涂层的磨损率。研究了温度对NiCoCrAlYTa防护涂层微动磨损的影响，结果表明在550 ℃至750 ℃范围内，NiCoCrAlYTa防护涂层的磨损率随温度的升高而有所增加。

The combination of high specific strength and oxidation resistance at elevated temperature makes TiAl alloys promising for the blades of high-pressure compressor in aero-engines. Due to the blade centrifugal force and system vibration, elevated-temperature fretting wear occurs at the tenon of the blade. In the present study, the elevated-temperature fretting wear of a TiAl alloy and protective coatings were studied.The fretting wear behavior and mechanism of the TiAl alloy at 550 ℃ were studied based on the fretting condition of high-pressure compressor blades. The results revealed that severe adhesive wear, peeling and abrasive wear occured on the surface, which resulted in the fluctuation of the friction coefficient and high wear rate. After a certain number of fretting cycles, the wear debris was compacted and tribo-sintered to form a tribolayer. Nanocrystalline microstructure made the tribolayer have high hardness, H/E and wear resistance. The formation of the tribolayer led to a decrease in the wear rate of the TiAl alloy.The fretting wear resistance and mechanism of two MCrAlY coatings were investigated. CoCrAlYSi coating demonstrated abrasive wear, peeling and severe adhesive wear when fretting at 550 ℃. The tribo-oxidation of CoCrAlYSi formed a large amount of oxides with low self-diffusion coefficient, which resulted in the formation of a tribolayer with a large quantity of pores. The pores led to severe peeling of the tribolayer under fretting and a low coverage of the tribolayer in the wear scar. Consequently, larger areas of CoCrAlYSi were exposed to the counterpart, resulting in high friction coefficient and wear rate. NiCoCrAlY coating formed less oxides with low self-diffusion coefficient after tribo-oxidation, which resulted in the formation of a tribolayer with a small quantity of pores. The tribolayer presents high wear resistance, high coverage in the wear scar, and inhibited the adhesive wear of NiCoCrAlY. With the high coverage of the tribolayer, less areas of NiCoCrAlY were exposed to the counterpart. Consequently, both the friction coefficient and the wear rate of NiCoCrAlY coating were low.The effect of Ta on the fretting wear of NiCoCrAlYTa coating was studied. The solid solution strengthening of Ta improved the nanohardness of the coating. The solid solution and dispersion strengthening of Ta and its oxides strengthened the tribolayer. As a result, the fretting wear resistance of the coating was further improved. The effect of hBN on the elevated-temperature fretting wear of NiCoCrAlYTa coating was studied. It was found that hBN reduced the friction coefficient and increased the wear rate of the coating. The influence of temperature on the fretting wear of NiCoCrAlYTa coating was invesitigated. The results demonstrated that the wear rate of the coating increased with the increase of temperature from 550 ℃ to 750 ℃.