Brazing C/SiC composites and Nb with TiNiNb active filler metal

C/SiC composites and Nb were vacuum brazed with the Ti39·4Ni39·4Nb21·2 alloy being the active filler metal. The mechanical properties of the filler material, the microstructure and the strength of brazing joints were investigated. The results showed that the filler TiNiNb alloy has a tensile strength of 860 MPa, an elongation of 51% and an elastic modulus of 78 GPa. Both Ti and Nb elements in the filler reacted with C/SiC during the brazing process, and a well bonded C/SiC–Nb joint was obtained. The ductile filler metal released the thermal stress in the joint. When the brazing was performed at 1220°C for 20 min, the shear strength of brazed joints reached 149, 120 and 73 MPa at 20, 600 and 800°C respectively.