Abstract: C/C composite and TC4 alloy were brazed successfully by using AgCuTi+0.3%C_f filler. The interfacial microstructure was investigated by the SEM, EDS and TEM. The mechanical property of the joints was characterized by the universal testing machine. The microstructure and mechanical property of the joints brazed at different temperatures were analyzed. The process of joint formation was analyzed, and the role of carbon fiber in each stage of joint formation was revealed. Results show that with the increase of the brazing temperature, Ti activity and element diffusion rate increased, so that the thickness of reaction layers on both sides of joints and Ti-Cu compounds in the center of brazing seam increased. The shear strength of joints first increased and then decreased with the increase of brazing temperature, and the maximum strength of 28.5 MPa was obtained when the brazing temperature was 900℃ and the holding time was 10 min. The formation process of C/C/AgCuTi+C_f/TC4 joints could be divided into four stages:melting of filler, and dissolving of TC4 alloy; element enrichment, and formation of reaction layer; isothermal precipitation, and movement of liquid phase; joint formation. Carbon fiber played an important role in the formation of the joint, which regulated the microstructure and residual stress of the brazed joint and improved the mechanical property of brazed joint.

Key words: brazing, C/C composite, composite filler, microstructure, mechanical property, joint formation