Effects of different Ti content in Zn-30Al filler metals on the microstructure and mechanical properties of Mg-Al butt joints

Based on the idea of alloying welding seam, a series of Zn-30Al-xTi filler metal was used to join Mg/Al dissimilar metals by tungsten inert gas welding, where the x was 0, 0.05, 0.1, 0.5, and 1, respectively. The effect of various Ti content on the microstructure and the mechanical property of Mg-Al butt joints was investigated. Results indicated that the fusion zones of the joints were mainly composed of alpha-Al, MgZn2 and Al-Zn eutectics when the Ti content was 0.05, 0.1 and 0.5 wt.%, and Al3Ti compounds could precipitate first and act as nucleuses during solidification process when the Ti content was appropriate. The mechanical property of the weld joints improved consistently to the increasing content of Ti. The optimum average tensile strength of the joints reached 148 MPa when Zn-30Al-0.5Ti was used, but the average tensile strength decreased again when Zn-30Al-1Ti was used.