采用OM、SEM、TEM等手段对TC11和TC17钛合金线性摩擦焊接界面的显微组织进行了分析。结果表明，在焊合界面处发生了动态再结晶，形成了共有晶粒和共有晶界，共有晶粒内焊合界面处形成了一个相界面。合金元素在共有晶界和共有晶粒内相界面处均发生了相互扩散。在共有晶粒和共有晶界形成过程中对溶质元素的排斥、吸附与拖曳作用下，共有晶粒内相界面处合金元素的变化范围比共有晶界处宽，且焊合区相界面处的成分变化要大于相内部。焊合界面处形成了大量细小的针状α相，其内有大量的变形孪晶。共有晶粒内的焊合界面的微观结构包括2个界面(两侧材料各自的再结晶生长界面)和2个生长区(有序和无序)，该处动态再结晶也有类似于凝固结晶的有序和无序结晶过程。

As a solid-state welding technology, linear friction welding has unique advantages in machining dissimilar titanium alloy blade disc. However, there still lacks sufficient support in basic applied research, and the mechanism of interface formation is still under study. In this work, the microstructure of the welded joint between TC11 and TC17 titanium alloys was analyzed by OM, SEM and TEM, respectively. The results showed that common grains and common grain boundaries are formed at the weld interface. In the common grain, a phase boundary is formed in the weld interface. Elements diffusion is observed on both sides of the common grain boundary and the phase boundary in the common grain. Under the action of rejection, adsorption and towing of solute elements in the formation of common grains and common grain boundary, the observed diffusion distance of elements in the phase boundary of the common grain is longer than the one in the common grain boundary. The composition change at the phase boundary of the weld zone is greater than the one inside the phase. A large number of small needle-like α phases are formed at the weld interface that has a large number of deformed twins. The structure of the interface in common grains consists of two interfaces (recrystallization growth interfaces of both sides) and two growth regions (ordered and disordered). The dynamic recrystallization also has an ordered and disordered crystallization process similar to that of solidification crystallization.