Effect of Zr Content on the Microstructure and Properties of TC4 Titanium Alloy Joints Brazed with TiZrCuNi Brazing Paste

Four groups of TiZrCuNi brazing powders with different Zr contents were prepared by vacuum melting-atomization method, and four groups of brazing pastes with different Zr contents were obtained by mixing the brazing powders with a certain proportion of solvents and activators, and the melting characteristics of the brazing pastes and the wettability on Ti-6Al-4V were tested. Four brazing pastes were used to vacuum braze the TC4 titanium alloy, and the brazed joints were tested for microstructure, microhardness tensile, and shear strength. The results show that with the increase of Zr element content in brazing paste, the brazed joint width, tensile strength, and shear strength showed a tendency of increasing and then decreasing. When the Zr content in the brazing paste was 16.5%, the (Ti,Zr)2(Cu,Ni) compounds in the brazed joints were more precipitated and most uniformly distributed, and the shear resistance reached the best level of 375.6 MP, with excellent mechanical properties of the brazed joints.