基于正交相可控生成的Ti-Al-Nb-Mo合金的组织控制和力学性能优化

Ti2AlNb合金凭借优异的高温强度、耐腐蚀性、高温抗氧化性等优点，成为航空航天领域中最具发展前景的轻质高温金属结构材料之一。制备方法、合金元素和热处理工艺对改善其综合性能具有关键作用。在此背景下，本项目拟在预合金粉末中引入Mo组元，通过热等静压制得Ti-Al-Nb-Mo合金，结合相变过程分析和组织分析，探明Ti-Al-Nb-Mo合金烧结过程中物相演变规律；澄清烧结过程中O→α2、O→B2相转变的动力学机制。对变形各阶段的组织进行分析，并结合变形诱导相变过程分析，对变形全过程的机理进行阐释，据此指导热处理工艺的优化，实现O相的可控析出和合金的组织调控，为类似合金可控成相提供理论依据和参考。利用显微组织观察和力学性能测试，建立工艺-组织-力学性能关系，并获得具有优异室温和高温性能的Ti-Al-Nb-Mo合金。

Ti2AlNb alloys have several advantages including excellent high temperature strength, corrosion resistance, high temperature oxidation resistance and so on, which makes it become one of most promising candidates in the aviation and space fields. Preparation method, heat treatment and alloy elements are the key factors determining the alloys’ comprehensive properties. Thus, by introducing element Mo into the pre-alloyed powder, a Ti-Al-Nb-Mo alloy will be acquired by hot isostatic pressing (HIP) sintering in this project. Combining phase transformation process and microstructure analysis, phase transformation mechanism during the sintering process will be explored. Besides, thermodynamic mechanism of transition O→α2 and O→B2 will be clarified. In addition, taking the deformation induction transformation into consideration, the mechanism of whole deformation process will be clarified by analyzing the microstructure transformation of the alloy during different periods of the deformation process. Based on above researches, by optimizing thermomechanical processing, controllable precipitation of O phase and microstructure regulation will be realized, which will provide support and guidance for phase controlling in similar alloys. Furthermore, by combining microstructure observation and mechanical properties testing, bridges among processing, microstructure, and mechanical properties will finally be built and an ideal Ti-Al-Nb-Mo alloy with superior properties at both ambient and high temperature will be acquired.