Effects of cerium and SiC mixed particles on nanoparticle strengthening activated TIG-welded AZ31 alloy joints

AZ31 magnesium alloy sheets were A-TIG-welded through a coating of flux, which contained different ratios of Ce powder and nano-sized SiC as reinforcement particles and equal mass of TiO2as activating fluxes. The microscopic analysis results illustrated that relatively low content of Ce in the reinforcement particles caused the formation of Al3Ce precipitates and refined the grains of α-Mg phase together with β-Mg17Al12and SiC particles. The increase in microhardness and ultimate tensile strength of the joints was 6.2% and 19.2%, respectively, when reinforcement particles contain 20 wt% Ce compared to the joints coated without Ce. By studying the electrochemical test results, when using 20 wt% Ce + 80 wt% SiC as reinforcement particles, the corrosion current density was the lowest and the corrosion resistance reached the largest value, reflecting the improvement of corrosion property of the joint affected by Ce element.