The linear friction welding (LFW) experiment of Ti

2

AlNb and Ti60 alloys was conducted. The microstructure evolution of the joint was analyzed by using an optical microscope and scanning electron microscope

and the mechanical property of the joint was tested as well. The results reveal that the microstructures of thermo-mechanically affected zones (TMAZ) on both sides of the joint deform along the direction parallel to weld interface. α

2

→B2 and O→B2 transformations occur in TMAZ of the Ti2AlNb side joint in which the fraction of B2 phase is higher than that of base metal; β→metastabl

e β→α transformations occur in TMAZ of the Ti60 side joint

resulting in fine lamellar secondary α precipitation. Dynamic recrystallization happens in weld zones (WZ) on the two sides of the joint. During welding

the WZ of Ti

2

AlNb side joint completely transformed into B2 phase and retained after rapid cooling; the WZ of Ti60 side joint is firstly transformed into high-temperature β

and then β→α′ transformation occurs during fast cooling

leading to α′ martensite precipitation. In addition

interdiffusion of solute elements occurs at the weld interface

forming an element diffusion layer about 1 μm in width

and the grains on two sides of the weld interface are intergrowth. Under the coupling effects of strain strengthening and precipitation strengthening of TMAZ and fine grain strengthening and precipitation strengthening of WZ

the tensile strength (939 MPa) of the joint is not lower than that of Ti60 base metal

and the fracture mode is ductile fracture.