Effect of zirconium on microstructure and properties of Zn-15Al filler metal

The microstructure and properties of Zn-15Al filler metal used for brazingof aluminum/stainless steel were investigated by means of scanning electron microscope, X-ray diffraction and nanoindentation. The results indicate that Zr addition hasfew influences on the melting point of the Zn-15Al filler metal. Moreover, the addition ofthe appropriate amount of Zr appears to refine the η-Zn dendrites in the filler metal. However, the excessive amount of Zr leads to the formation of Al₂ZnZr compounds. The spreadability of the Zn-15Al-xZr filler metal is improved especially at the Zrcontent of 0.2 wt.%, which the spreading areason stainless steel and aluminum alloy are increased by 15.9% and 10.2%, respectively. The shear strength of the Zn-15Al-0.2Zr brazed joint achieves the peak value of 143 MPa. The creep stress exponents of Zn-15Al, Zn-15Al-0.2Zr and Zn-15Al-0.3Zr are 6.64, 7.35 and 8.07, respectively.