Effects of Ti on the Brazability of Zn-22Al-xTi Filler Metals as Well as Properties of Cu/Al Brazing Joints

Noval Zn-Al-Ti filler metals have been designed and used to braze Cu and Al dissimilar metals. The phase constitutions and morphologies of intermetallic compounds at the Zn-22Al-xTi/Cu interfaces were studied in this paper. The results indicate that, with Ti addition from 0.01 wt% to 0.05 wt%, the microstructure of the Zn-22Al alloy are refined significantly. The spreading area of Zn-22Al-0.03Ti on Cu substrates increases by 60.4% compared with that of ZA. However, the melting range and melting point of the Zn-22Al-xTi alloys also increase with the addition of Ti. In particular, the addition of trace Ti into the Zn-22Al filler metal can refine the microstructures and decrease the thickness of the intermetallic compounds layer produced in the Cu/Al brazing. The shear strength of Cu/Al joint brazed with Zn-22Al-0.03Ti is 13.4% higher than that of the Zn-22Al filler metal, and the fracture position changes from the interface layer to the matrix of the filler metals. The X-ray diffraction result indicates that the CuAl2, CuZn, and Cu9Al4 phases are produced at the filler metal/Cu substrate interface