Effect of brazing parameters on microstructure and mechanical properties of C_f/SiC and Nb-1Zr joints brazed with Ti-Co-Nb filler alloy

Reliable brazing of carbon fiber reinforced SiC (C_f/SiC) composite to Nb-1Zr alloy was achieved by adopting a novel Ti45Co45Nb10 (at.%) filler alloy. The effects of brazing temperature (1270–1320 °C) and holding time (5–30 min) on the microstructure and mechanical properties of the joints were investigated. The results show that a continuous reaction layer (Ti,Nb)C was formed at the C_f/SiC/braze interface. A TiCo and Nb(s,s) eutectic structure was observed in the brazing seam, in which some CoNb₄Si phases were distributed. By increasing the brazing temperature or extending the holding time, the reaction layer became thicker and the amount of the CoNb₄Si increased. The optimized average shear strength of 242 MPa was obtained when the joints were brazed at 1280 °C for 10 min. The high temperature shear strength of the joints reached 202 MPa and 135 MPa at 800 °C and 1000 °C, respectively.