新型高铌β型γ-TiAl合金细晶材料的制备及其热变形行为研究

High Nb-containing TiAl alloy is considered as the best example for developing high-temperature and high-strength TiAl alloys, and the serious micro-segregation and poor hot-workability problems of common high Nb-TiAl alloys are expected to be solved by introducing novel β-γ TiAl alloys with high Nb content. Meanwhile, fine-grained β-γ TiAl alloys are found to exhibit excellent hot workability, however, neither single hot canned forging nor extrusion can produce block TiAl materials with fully fine and uniform microstructures. So far, there are few reports about the fabrication process and hot deformation behaviors of block high Nb-TiAl materials with fine-grained B2/β + γ microstructure. In the present program, the fabrication process of Mo-alloyed novel high-Nb β-γ TiAl materials with fine grains，their hot-compression and high-temperature superplastic deformation behaviors, the relevant microstructure evolution rules and deformation mechanisms, as well as the mechanical properties will be studied systematically. After successful completion of this program, the inter-relationship of microstructure, hot-deformation behavior and macro properties of fine-grained high-Nb β-γ TiAl alloy can be revealed, which will provide theoretical foundation and open up new way for developing novel high-Nb TiAl alloys and their hot processing technologies.

高铌γ-TiAl是发展高温高强γ-TiAl合金的典范，而研制高铌的β型γ-TiAl合金有望解决当前高铌TiAl合金凝固组织偏析严重和高温变形能力较差的问题；细晶的β型γ-TiAl合金组织具有非常优异的热加工变形能力，然而单一的高温锻造或挤压都不能得到组织均匀细小的大块TiAl合金材料。当前关于细晶β/B2 + γ组织特征的高铌TiAl合金的制备及其热变形行为还鲜有报道。本课题围绕Mo合金化的新型高铌β型γ-TiAl细晶材料的制备、β/B2 + γ细晶组织高铌TiAl合金的热变形行为和高温超塑性变形行为、热变形过程中组织的演化规律和变形机制、力学性能进行系统研究，揭示细晶的高铌β型γ-TiAl合金显微组织-热变形行为-宏观力学性能之间的相互关系，为新型高铌TiAl合金的研制和热加工技术开辟新途径并奠定理论基础。

高铌γ-TiAl是发展高温高强γ-TiAl合金的典范，而研制高铌的β型γ-TiAl合金有望解决当前高铌TiAl合金凝固组织偏析严重和高温变形能力较差的问题；细晶的β型γ-TiAl合金组织具有非常优异的热加工变形能力，然而单一的高温锻造或挤压都不能得到组织均匀细小的大块TiAl合金材料。当前关于细晶β/B2 + γ组织特征的高铌TiAl合金的制备及其热变形行为还鲜有报道。本课题围绕Mo合金化的新型高铌β型γ-TiAl细晶材料的制备、β/B2 + γ细晶组织高铌TiAl合金的热变形行为和高温超塑性变形行为、热变形过程中组织的演化规律和变形机制、力学性能进行系统研究，揭示细晶的高铌β型γ-TiAl合金显微组织-热变形行为-宏观力学性能之间的相互关系，为新型高铌TiAl合金的研制和热加工技术开辟新途径并奠定理论基础。