Understanding the microstructure evolution mechanism and the microstructure-strength correlations of Ti₃SiC₂/Ti₂AlNb joint brazed with AgCu interlayer

Herein, a Ti₃SiC₂ ceramic was brazed to a Ti₂AlNb alloy using an AgCu foil. The effect of brazing parameters on the microstructure of the brazed joint was investigated. Through careful characterizations of the interfacial reaction products, the microstructure evolution mechanism of the brazed joint was clarified. The unique crystal structure of the Ti₃SiC₂ phase leads to the effortless de-intercalation of Si atoms. The de-intercalated Si atoms react with Ti atoms, which dominate a series of complex interfacial reactions. The influence of brazing temperature on these interfacial reactions is strong. Maximum shear strength of 89 MPa was achieved when the joints were brazed at 860 °C for 20 min. A sound joint benefits from the detachment of Ti–Si–Cu interfacial reaction layers from the ceramic surface, the mutual diffusion zone inside the Ti₃SiC₂ ceramic, and moderate TiCuSi and Ti₅Si₃ brittle compounds in the brazed seam.