Effect of Cooling Rate on Solidification Structure of Zinc–Aluminum–Magnesium Alloy

Abstract

Zinc–Aluminum–Magnesium coating are paid more attention recently due to the appearance of the surface and superior corrosion resistance. The research on the solidification structure of Zinc–Aluminum–Magnesium alloy is less. In this paper, the solidification structure of Zinc–Aluminum–Magnesium alloy with different zinc content and aluminum content under water cooling, air cooling and furnace cooling conditions was studied. The industrial pure Zinc (99.99 wt%), industrial pure Aluminum (99.99 wt%), Magnesium and Zinc alloy (Mg₁₁Zn) were selected for smelting in resistance furnace. The molten alloy components were Z3A3M (3 wt% Al, 3 wt% Mg), Z5A3M (5 wt% Al, 3 wt% Mg). The solidification structure of the alloy was observed by scanning electron microscopy. The composition of the phase was analyzed by X-ray Diffraction (XRD). The corrosion property of the alloy was analyzed by electrochemical experiment. It was found that four phases existed in these two alloys: Zn phase, Al phase, AlMg₄Zn₁₁ phase and Mg₂Zn₁₁ phase in different cooling modes. And in air-cooled conditions, the two alloys showed a good corrosion resistance.