原位构筑Ti2AlC/TiAl仿生层状复合材料及其构型-界面协同强韧化机制

TiAl合金是航空航天领域理想的轻质高温结构材料，在TiAl中引入兼顾金属和陶瓷特性的Ti2AlC有望在保持低密度和高强度的基础上改善其室温塑性。但目前研究表明弥散分布Ti2AlC/TiAl复合材料存在室温强度-塑韧性倒置关系，其室温塑韧性远未达到预期水平。针对这一瓶颈性难题，本研究以复合材料宏观性能取决于微观组织(复合构型和界面结构)为出发点，基于Ti-Al-C反应体系并结合片状粉末冶金技术原位构筑Ti2AlC/TiAl仿生层状复合材料，旨在实现层状构型和复合界面协同强塑韧化的目标。通过先进的实验表征和多尺度计算模拟方法对Ti2AlC/TiAl仿生层状复合材料的构型演变规律、界面结构特征及键合性质、构型-界面与位错/微裂纹的动态交互作用等进行研究，揭示该复合材料的原位合成及构型调控机理，阐明其构型-界面协同强韧化机制。本研究可为我国轻质高温结构材料的发展提供理论和技术支撑。

TiAl alloys are the idea lightweight and high-temperature structural materials in the field of aerospace due to their excellent properties, the Ti2AlC/TiAl composite could effectively improve the plastic deformation capacity of TiAl alloys while maintaining the advantage of low density and high strength. However, the previous investigations have shown that the Ti2AlC/TiAl composite with the dispersive distribution has encountered the well-known dilemma of strength-ductility trade-off, and its room temperature toughness is far from the expected level. In order to solve this bottleneck problem, based on the concept of the macroscopic properties for a composite depend on its microstructure (composite configuration and interface structure), the Ti2AlC/TiAl composite with the biomimetic micro-nano laminated structure would be in-situ fabricated based on the Ti-Al-C reaction system and the flake powder metallurgy method in order to fully realize the strengthening and toughening potential caused by the synergistic action of layered configuration and interface microstructure. The task of this investigation is to reveal the in-situ fabrication mechanism, configuration control mechanism and microstructure-properties correlation mechanism of Ti2AlC/TiAl biomimetic laminated composite by clarifying the important scientific issues, such as microstructure evolution, interface microstructure characteristic and bonding properties, dynamic interaction between configuration-interface and dislocation/micro-crack. The present investigation could provide theoretical basis and technical support for the development of lightweight and high-temperature structural materials in our country.