Effects of Bi and rare earth metal on the microstructure and properties of Zn-based high-temperature solder

A novel Zn-based high-temperature solder was developed to join copper/steel at moderate temperature.The effects of Bi and rare earth metal on the microstructures,wettability of solders as well as the mechanical properties of solder joints were investigated.The results indicated that with the addition of Bi into Zn-Cu-Sn（ZCS） alloy,significant improvement in wettability is realized.When the content of Bi element is 1.5 wt.%in the solder,the spreading area researched over 200 mm.Furthermore,with the addition of RE,refined primary ε-CuZn₅ phases were formed and the shear strength of the solder joint was largely improved.