铸造γ-TiAl合金晶粒细化方法研究进展

Research Progress on the Grain Refinement Method of Castγ-TiAl Alloys

γ-TiAl合金因其低的密度、高的强度、优异的高温性能,是具有良好应用前景的新型轻质高温结构材料。γ-TiAl合金可部分替代Ni基高温合金,目前已应用于飞机发动机热端部件如低压涡轮叶片、气门阀、汽车发动机排气阀等热端构件。随着现代工业高速发展,未来高温部件的服役环境越发苛刻,超越现有γ-TiAl合金服役温度、改善室温和高温力学性能仍是具有挑战性的前沿课题。本文综述了铸造γ-TiAl合金凝固特点和近年来晶粒细化研究进展。从合金成分角度,探讨了凝固组织析出规律及形成微观偏析的影响因素。同时,针对微观偏析和晶粒粗大等问题,详细总结了γ-TiAl合金的晶粒细化方法。最后介绍了借助亚稳组织细化晶粒的新方法及影响因素,并提出了现有细化方法面临的问题,为γ-TiAl合金制备和发展提供参考。

Due to the low density,high strength and excellent high-temperature performance,γ-TiAl alloys are new lightweight high-temperature structural materials with good application prospects.γ-TiAl alloys can partially replace Ni-based superalloys,which have been used in hot end parts of aircraft engines,such as low-pressure turbine blades and valves,automotive engine exhaust valves and other hot end components.With the rapid development of modern industry,the service environment of high-temperature components in the future will become increasingly harsh,and it will be a challenge to exceed the service temperature of existingγ-TiAl alloys and improve their mechanical properties.In this paper,the solidification characteristics of castγ-TiAl alloys and recent research progress on grain refinement are reviewed.The characteristics of the solidification behavior and corresponding microsegregation behavior of the alloy are discussed.At the same time,to solve the problems of microsegregation and refine the grain size,the grain refinement methods forγ-TiAl alloys are summarized in detail.Finally,a new method of grain refinement with a metastable microstructure is introduced,and the problems faced by the existing refining methods are described,which can provide guidance for the production and development ofγ-TiAl alloys.