随着我国装备制造发展，钛/铝对-搭接结构使用比例逐渐增加，本项目以提高钛/铝对-搭接结构连接质量为目标，提出双源超声辅助钛/铝对-搭接FSW思想，利用“双声源”超声能场调控合理化超声能输入，优化钛/铝对-搭接FSW过程。首先，通过探明双声源特性改变与超声能场调控的联系，掌握超声能场调控理论；其次，探究超声能场调控下的界面微区钛、铝组织演变，揭示原子扩散机制，明确原子扩散对界面微区反应产物形成及生长行为的影响，阐明超声能场调控对界面微区演变的作用；再次，探明钛/铝对-搭接界面微区组态对结构承载性能的影响，分析结构在形变过程中的裂纹演化，明晰非均质组织引发的微观强度错配对裂纹萌生、扩展的作用，阐释结构断裂机理，理解超声能场调控对结构承载特性的影响；最后，构建“工艺-组织-性能”框架，实现高效钛/铝对-搭接FSW。项目开展为钛/铝对-搭接FSW提供“双源超声辅助”新思路，具有重要理论与工程意义。

With the development of equipment manufacturing, the requirement of Ti/Al butt-lap structure is increasing in our country. In order to improve the quality of Ti/Al butt-lap structure, double-ultrasonic assisted FSW was proposed to join the Ti/Al butt-lap structure in this project. The ultrasonic field of “double-ultrasonic” was controlled in order to rationalize the ultrosonic input, optimizing the thermal - mechanical condition and behaviors of FSW. Firstly, based on the relationship between the variation of double-ultrasonic characteristic and ultrasonic field controlment, the theory of ultrasonic field controlment was developed and understood. Secondly, the microstructural evolution of Ti and Al in the interfacial region under the controlling of ultrasonic field was researched, revealing the diffusion mechanism. Besides, the effect of atomic diffusion on the formation and growth of reactants in the interfacial region was comprehended, and the influence of ultrasonic field controlment on the microstructural evolution of interfacial region was also illustrated. Thirdly, the impact of microstructure of butt-lap interfacial region on the mechanical properties was revealed, moreover, the evolution of crack during deformation was analyzed. The effect of micro-strength mismatch caused by the inhomogenous microstructure on the formation and transformation of crack was studied, and the failure mechanism of structure was revealed. Moreover, the effect of ultrasonic field controlment on the mechanical characteristic was also understood. Finally, the relationship of “parameters-microstructure-mechanical properties” was illuminated, aiming at improving the efficiency of Ti/Al butt-lap FSW. The new idea of “double-ultrasonic assisted FSW” is proposed for the Ti/Al butt-lap structure, and the theoretical- and engineering-significance of this project are important.