Abstract: Using self-made Ti-Zr-Cu-Ni-Sn filler metal to braze TA2 titanium alloy, the melting characteristics, microstructure and phase, wetting and corrosion resistance, and tensile strength of joints of modified Ti-Zr-Cu-Ni filler metals with different contents of Sn were studied. The results show that with the increase of Sn content, the solid and liquidus temperature of Ti-Zr-Cu-Ni-Sn filler metals basically increase, but the temperature difference is basically narrowed, which better inhibits the formation of brittle compounds at the brazing interface. The microstructure of the Ti-Zr-Cu-Ni-5Sn filler metals is composed of Ti, Zr matrix and crystal phase. Sn is more inclined to combine with Ti and Zr to form low melting point eutectic phases such as Ti₂Sn₃, Ti₆Sn₅, Zr₅Sn₃, et al. When Sn≤1.5%, the wettability of this filler metal to the TA2 titanium alloy is gradually deteriorated. Continuing to increase the Sn, the wettability of the filler metal is improved, and the filler metal containing 5%Sn has the best wetting to the matrix. The erosion of TA2 titanium alloy is weakened by adding 5%Sn and reducing the total amount of Cu and Ni. Under the same brazing process, the strength and plasticity of the brazed joint with 5% Sn are improved. With the increase of the brazing temperature, the Ti-Zr-Cu-Ni filler metals produces more strengthening phases, which leads to a significant increase in the strength of brazed joint, however, the strengthening effect of Sn-containing phase produced by Ti-Zr-Cu-Ni-5Sn filler metal on strength of brazed joint is limited. In contrast, the brazing temperature has a greater impact on the strength of brazed joints.

Key words: titanium-based filler metal, melting properties, microstructure, erosion properties, tensile properties