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采用现代测试技术,较详尽地研究了TiAl基合金工程材料的强韧化原理、新工艺和新技术。 在合金化方面,探讨了Sb、Pb、Sn和Nd的添加对TiAl基合金显微组织和室温力学性能的影响。其中,Sb具有显著改善 TiAl基合金室温力学性能和高温抗氧化能力的作用。TiAl+Sb合金室温变形时,α_2/γ层片状晶粒的γ板条内形成大量变形孪晶。TiAl+Sb合金的抗氧化性甚至优于Ti-48Al-2Cr-2Nb合金。 在晶粒细化剂的研究中,发现BN可使TiAl基合金铸态晶粒显著细化,其效果优于XD~(TM)技术中的TiB_2。 在TiAl基合金的表面化学热处理的开创性的探讨中,发现渗碳处理可有效地强化TiAl基合金表层,从而明显地提高合金的室温力学性能。多层、复杂结构的渗碳层具有良好的组织热稳定性和抗氧化性,因而使TiAl基合金抗高温长时间氧化能力得到显著改善。 较全面地探讨了TiAl基合金常规热加工和热处理的金属学原理,讨论了常规热处理对热变形TiAl基合金试样的局限性。在此研究基础上,提出了双温热处理新工艺。研究了双温热处理对TiAl基合金热变形试样的显微组织和室温拉伸性能的影响。探讨了双温热处理的金属学原理。
Using modern testing technology, the toughening principle, new technology and new technology of TiAl-based alloy engineering material are studied in detail. In alloying, the effects of Sb, Pb, Sn and Nd addition on the microstructure and room temperature mechanical properties of TiAl-based alloys were investigated. Among them, Sb has significantly improved the room temperature mechanical properties of TiAl-based alloys and high temperature oxidation resistance. When TiAl + Sb alloy is deformed at room temperature, a large amount of deformation twins are formed in the γ-lath of α_2 / γ lamellar grains. The oxidation resistance of TiAl + Sb alloy is even better than Ti-48Al-2Cr-2Nb alloy. In the study of grain refiner, it is found that BN can remarkably refine the as-cast grain of TiAl-based alloy, which is better than that of TiB_2 in XD ~ (TM) technology. In the ground-breaking discussion on the surface chemical heat treatment of TiAl-based alloys, it was found that carburizing treatment can effectively strengthen the surface layer of TiAl-based alloy and significantly improve the room-temperature mechanical properties of the alloy. The carburized layer of multi-layer and complex structure has good thermal and oxidation resistance of the tissue, so that the oxidation resistance of the TiAl-based alloy for a long time under high temperature is remarkably improved. The metallographic principles of conventional hot-working and heat-treatment of TiAl-based alloys are discussed comprehensively. The limitations of conventional heat-treatment on hot deformed TiAl-based alloy specimens are discussed. Based on this research, a new dual temperature heat treatment process is proposed. The effect of bimetallic heat treatment on the microstructure and tensile properties at room temperature of TiAl-based alloy was investigated. Metallographic principles of dual-temperature heat treatment were discussed.