New Ti-Zr-Cu-Ni-La system brazing filler metals for the joining of titanium alloy

In order to research the influence of Zr content（below 15 wt.%） on the properties of the filler metal.Ti-SZr-5Cu-15Ni-La,Ti-10Zr-15Cu-l5Ni-La and Ti-l5Zr-l5Cu-15Ni-La filler metals were prepared.The wettability of the filler metals on Ti-6Al-4V was evaluated and the melting temperatures of the filler metals were tested by differential scanning calorimetry DSC).The microstructures and mechanical properties of the brazed joints were investigated.The results show that the wettability of the filler metals improves as the Zr content increases.Zr content has great influence on the melting temperature of the filler metals.When Zr content changes from 5 wt.%to 10 wt.%and 15 wt.%,the melting temperature decreases about 80 ℃.The brazed joint with Ti-5Zr-15Cu-lSNi-La filler metal shows aciculate phase on the interface.The brazed joints with Ti-10Zr-15Cu-15Ni-La and Ti-15Zr-15Cu-15Ni-La filler metals consist of three zones,a segregated center zone,diffusion reaction zone and acicular zone.The brazed joint with Ti-5Zr-15Cu-15Ni-La filler metal achieves the maximum shear strength 313.9 MPa.