高性能TiAl基复合材料内外“双层”耦合增强结构形成机制与优化调控

TiAl基复合材料具有低密度、高比强度、优异的抗氧化性能和抗蠕变性能等优点，是替代镍基高温合金实现航空航天发动机大规模减重的首要候选材料。然而，TiAl基复合材料高温强度不足且室温塑性较差，难以满足航空航天工业对高温结构材料的性能要求。为解决上述瓶颈问题，本项目创新性地设计一种兼具内层增强结构(基体单元内部碳化物增强体弥散分布)与外层增强结构(基体单元界面层硼化物和碳化物呈准连续网状分布)的TiAl基复合材料，通过揭示B和C元素比例对TiAl基复合材料内、外“双层”增强结构演化的影响规律，建立基体单元及其界面层组织结构演化与材料力学性能的内在关联，阐明材料内、外“双层”耦合增强结构的形成机制，实现材料内、外“双层”耦合增强结构的优化调控，进而显著改善材料的室温塑性和高温强度，为发展高性能TiAl基复合材料制备新理论与新技术、推动TiAl基复合材料在航空航天领域的广泛应用奠定坚实基础。

TiAl matrix composites exhibit the advantages, such as low density, high specific strength, excellent oxidation and creep resistance, etc. Therefore, TiAl matrix composites become the preferred materials to replace nickel-based alloys and then achieve large-scale weight reduction of aerospace engines. However, due to the insufficient strength at high temperature and the poor plasticity at room temperature, TiAl matrix composites could not meet the requirements for high temperature structural materials in aerospace industry. In order to solve above bottleneck problems, this project innovatively designs a TiAl matrix composite, which consists of the inner reinforced structure (the dispersive distribution of carbides reinforcement in the matrix unit) and the outer reinforced structure (the borides and carbides distribute as quasi-continuous network in the interface layer of the matrix unit). This project would reveal the effect of boron and carbon elements ratio on the evolution of inner and outer "double layers" reinforced structure, establish the intrinsic relationship between matrix unit cooperating interface layer structure evolution and the mechanical properties, clarify the formation mechanism of the inner and outer "double layers" coupled reinforced structure, achieve the optimal regulation of the inner and outer "double layers" coupled reinforced structure, improve the plasticity at room temperature and the strength at high temperature of the materials. This project lays a solid foundation for the new theory and technology development of high performance TiAl matrix composites preparation and the wide application promotion of TiAl matrix composites in aerospace field.