Effect of Zn on Microstructures and Properties of Mg-Zn Alloys Prepared by Powder Metallurgy Method

Mg-Zn alloys were prepared by a powder metallurgy method using Mg powder and Zn powder as starting materials. The effects of the Zn content on sintering density, microstructure, phase composition, bending properties and micro-hardness of the Mg-Zn alloys were studied. The corrosion resistance of the Mg-Zn alloys was also measured. The function mechanism of Zn element during the powder metallurgy process was analyzed. Results show that the sintered compacts have finer grain size and higher sintered density upon Zn addition. The density of the sintered products increases with the increasing of Zn content. XRD analysis shows that the Mg-3 wt% Zn alloy is mainly composed of alpha-Mg phase. When the content of Zn is 4 wt%, the Mg-Zn alloys is composed of alpha-Mg and MgZn2 phases. With the increase of the Zn content, the bending strength of the Mg-Zn alloys first increases and then decreases, but the micro-hardness HV of Mg-Zn alloys always increases. The bending strength and micro-hardness of Mg-3 wt% Zn alloys are 123.6 MPa and 1017 MPa, respectively, which are 58% and 45% higher than those of pure Mg samples. Corrosion resistance measurements show that the corrosion rate of the Mg-Zn alloys decreases with the addition of Zn element, and the Mg-3wt% Zn alloy shows the lowest corrosion rate and the best corrosion resistance.