Research progress of wrought TiAl alloys for aero-engine applications

TiAl alloys have advantages such as low density and excellent high-temperature mechanical properties. They can replace nickel-based superalloys in the application of aircraft rotor blades. On one hand, they can reduce the mass of the blades. On the other hand, they can reduce the centrifugal force generated by the rotation of the blades, realize the optimized design of the disk and shaft, and contribute to the weight reduction of the aero-engine structure. So far, the development of TiAl alloys has gone through three generations. The first-generation TiAl alloys have not been applied. The second-generation TiAl alloys (4822 and 45XD alloys) developed by the United States have been used in engineering. Various low-pressure turbine blades of aero-engine have been prepared by casting process, and the long-term service temperature of the blades is 650 ℃. At present, a variety of the third-generation TiAl alloys, including TNM, TNB, G8, etc., have been developed. These alloys have good comprehensive mechanical properties at 750 ℃. The third-generation TiAl alloys have not been used in engineering in the field of aero-engine. This paper reviews the development process of TiAl alloys for aero-engine, briefly summarizes the types of solid solution strengthening and precipitation strengthening elements in forged TiAl alloys, reviews the research process and current situation of the microstructure and properties, remelting process, hot working process and application of wrought TiAl alloys, analyzes the characteristics of three-phase and two-phase wrought TiAl alloys and elaborates the evolution of the microstructure and properties of two third-generation wrought TiAl alloys after long-term high-temperature exposure, providing a reference for the material selection of the third-generation wrought TiAl alloys by aero-engine designers.