铝/钛异种合金搅拌摩擦焊接头中脆性相的调控及其与性能的相关性

采用搅拌摩擦焊对焊接性差、但应用前景广泛的铝/钛异种合金进行连接，通过研究接头的组织、性能、相结构、元素扩散和塑性金属流动行为，揭示接头中脆性相的影响因素、分布规律，建立焊接工艺条件―塑性金属流动行为―微观组织结构－接头性能四者的对应关系，获得接头微观结构与宏观性能之间的内在联系，为优化工艺、获得优良接头奠定理论基础；在此基础上采用相界扩散溶解层理论和TFDC理论从电子层面上阐明接头中脆性相的形成机理，建立脆性相生成、长大和演变过程模型，通过添加微量元素等措施对脆性相的形成进行阻隔和干扰，控制脆性相的数量、大小和分布规律，提高接头的强度和质量稳定性。项目的顺利实施一方面可揭示异种金属搅拌摩擦接头中脆性相形成的内在本质和规律，在发展搅拌摩擦焊焊缝成形理论方面具有一定的学术价值；另一方面可实现铝/钛异种金属的优质连接，为其在航空、航天、高速铁路等行业的应用奠定基础。

Ti/Al disimilar alloys which have poor weldability and extensive applied foreground will be joined by friction stir welding in this project. The microstructure, properties, phase, elements distribution and flowing of plastic metals will be reseached and the influencing factor and regularity of distribution of the brittle phase will be revealed. The correspondence between welding parameters, flowing behavior of plastic metals, microstructure and properties of the welded joint will be established and internal relations between microstructure and macroscopic properties of the welded joint can be obtained. These works can establish theory base of process optimazation and get fine welded joint. The theory of interfacial layer diffusion dissolved will be used to reveale the formation mechanism of brittle phase from electron level. The produce, growing up and evolution model of the brittle phase will also be estabilished. Trace elements will be added between Ti/Al to separate and disturb the formation of brittle phase and the amount, size and distrbution regularity will be controlled, and the strengh and quality stability of the welded joint will be improved. The favorably implements of this project on one side will reveal the intrinsic nature and regularity of the brittle phase in the friction stir welded joint, on the other side can realized the fine joining of Ti/Al disimilar metals and establish the base of industrial applications such as aviation, aerospace and rapid transit railway.