轻量化制造是我国高端装备研发的迫切需求。异种金属复合焊接构件能最大限度利用材料各自的优点，获得更好的经济效益和社会效益，是实现轻量化制造的重要途径。项目针对航空、航天、轨道车辆等高端装备轻量化制造对高性能Ti/Al异种金属复合焊接结构的潜在需求，发展一种能用于Ti/Al搭接结构可靠连接的“搅拌摩擦点焊-钎焊-扩散焊”复合焊接新工艺。通过对复合焊接接头形成机理、微观组织结构、力学行为以及焊接工艺进行深入研究，阐明在搅拌摩擦点焊过程中瞬时热、力作用下同步实现钎焊和扩散连接的机制及其影响因素，揭示复合焊接接头力学性能与焊接工艺、接头形成机理之间的相关性，并以此为基础来优化工艺、提高接头力学性能，实现Ti/Al异种金属的优质、可靠连接，为其在新型飞机、高铁车辆等装备研发中的应用奠定基础，并对推动我国高端装备轻量化制造技术的发展起到一定的促进作用。

Lightweight manufacturing is an urgent need for the development of high-tech equipment in China. The dissimilar metal welded structure parts can take maximum advantage of their preponderances and obtain better economic and social benefits and it is an effective method to realize lightweight manufacturing. This project targets to develop a novel hybrid welding method, namely “friction stir spot welding-soldering-diffusion welding” (FSSW-S-DW)for reliable connection of titanium to Aluminum dissimilar metals, because the lightweight manufacturing of high-tech equipment such as aircraft, spacecraft and rail vehicles has potential needs for Ti/Al dissimilar metal welded structure. The weld formation mechanism, microstructure, mechanical behavior of Ti/Al welded joints and welding process will be researched in this project. Through these researches, the mechanism and influence factor of the soldering and diffusion welding under the effect of instantaneous heat and stress during frictions stir spot welding could be revealed and the correspondence between mechanical properties of the FSSW-S-DW welded joints, welding parameters and the weld formation mechanism will be established, which is the theoretical base for process optimization and improving mechanical properties of welded joints. The favorably implements of this project on one side will realize high quality and reliable connection of the Ti/Al dissimilar metal and establish the base of industrial applications such as new aircraft and high-speed rail vehicles, on the other side can play a certain role in promoting the development of lightweight manufacturing technology for high-tech equipment