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综述了TiAl基合金高温抗氧化研究进展,包括TiAl基合金氧化热力学/动力学、氧化膜组成和结构及其形成过程,以及提高合金高温抗氧化性的措施。研究结果表明,TiAl基合金高温氧化动力学一般遵循抛物线规律,且受到合金相组成和组织形貌的影响。氧化膜由外向内,主要呈TiO_2/Al_2O_3/Al_2O_3+TiO_2结构,氧化膜与基体界面处易形成降低合金抗氧化性的Z相(Ti_5Al_3O_2)和氮化产物(TiN,Ti_2AlN)。TiAl基合金中添加适量的Nb,Y,Si,Cr,Mo等元素,在改善力学性能的同时,可明显降低合金高温氧化增重。采用表面处理技术,包括表面离子注入、表面渗透扩散处理以及磷化处理等,可在合金表面形成保护层,显著提高TiAl基合金高温抗氧化性能,然而保护层的稳定性尚需提高。采用涂层技术,包括富Al涂层、陶瓷涂层以及新兴的复合涂层等,可有效地阻止氧向内扩散,抑制TiAl基合金在高温下的氧化行为。
The research progress of high temperature oxidation resistance of TiAl-based alloys is reviewed, including the thermodynamics / kinetics of oxidation of TiAl-based alloys, the composition and structure of the oxide films, and the measures to improve the oxidation resistance at high temperature. The results show that the kinetics of oxidation at high temperature of TiAl-based alloys generally follows the parabolic law and is influenced by the composition and microstructure of the alloy. The oxide film mainly consists of TiO_2 / Al_2O_3 / Al_2O_3 + TiO_2 from the outside to the inside, and the formation of Ti_5Al_3O_2 and TiN, Ti_2AlN, which reduce the oxidation resistance of the alloy, easily forms at the interface between the oxide film and the substrate. Addition of proper amount of Nb, Y, Si, Cr, Mo and other elements to TiAl-based alloy can obviously decrease the weight gain of the alloy under high temperature oxidation while improving the mechanical properties. The use of surface treatment techniques, including surface ion implantation, surface diffusion and diffusion treatment, and phosphating treatment can form a protective layer on the surface of the alloy to significantly improve the high temperature oxidation resistance of the TiAl-based alloy. However, the stability of the protective layer needs to be improved. The use of coating technology, including Al-rich coatings, ceramic coatings and emerging composite coatings, can effectively prevent oxygen from diffusing inward and inhibit the oxidation behavior of TiAl-based alloys at high temperatures.