微叠层TiBw-TiAl复合材料板材设计制备与强韧化机理研究

针对钛铝金属间化合物板材难于成形的瓶颈问题以及金属基复合材料强度—韧性（塑性）倒置问题，本项目提出一种具有仿生贝壳层状结构的TiAl基复合材料板材成形方法：以TiBw/Ti复合材料箔和纯Al箔为原料，通过热处理使Ti和Al发生化学反应结合真空热压烧结技术，设计并制备出全层片(α2-Ti3Al/γ-TiAl)层、等轴γ-TiAl层与TiBw-rich层三层交替排列结构的新型微叠层TiBw-TiAl复合材料板。研究热处理参数、原料箔材层厚以及增强相含量对TiBw-TiAl复合材料的层状组织演变与力学性能的影响规律，阐明组元层厚、层内组织细化和增强相含量与复合材料宏观力学性能的关系，揭示微叠层复合材料的强韧化机制与断裂机理。本项目将从结构设计上为实现钛铝金属间化合物的强韧化奠定理论基础，为轻质耐热高强金属间化合物板材制备提供新途径。

In order to solve the bottleneck problem of titanium aluminide intermetallic compounds sheet forming and the inverse relationship between strength and toughness/ductility of Metal matrix composites (MMCs), this project proposes a method for the production of TiAl matrix composite sheets with novel nacre-like structure: TiBw/Ti matrix composite foils and pure Al foils are selected as raw materials and stacked to obtain the (TiBw/Ti)-Al laminates, and subsequently reaction annealing and hot pressing sintering are employed to fabricate unique micro-laminated TiBw-TiAl composite sheet, which consists of alternating fully lamellar (α2-Ti3Al/γ-TiAl) layer, equiaxed γ-TiAl layer and TiBw-rich layer. TiBw-rich layer is actually TiAl matrix composite layer containing high contents of TiB whiskers. Effect of heat treatment parameters, thicknesses of TiBw/Ti and Al foils and volume fractions of TiBw reinforcements on micro-laminated microstructure evolution and mechanical properties of TiBw-TiAl composite sheets are systematically investigated. The relationship of constituent layer thicknesses, the refinement of microstructure, the volume fractions of reinforcements and mechanical properties is clarified. Finally, strengthening-toughening mechanism and fracture mechanism of novel micro-laminated TiAl matrix composites are revealed. This project will lay the theoretical foundation for improving the strength and toughness of titanium aluminide intermetallic compounds by microstructural design, and also provide a new approach for the sheet forming of lightweight high-strength titanium aluminide intermetallic compounds.