Effects of magnesium on microstructure, properties and degradation behaviors of zinc-based alloys prepared by selective laser melting

Abstract

Selective laser melting (SLM) technology was employed to manufacture Zn-3%Mg alloy and the effects of the addition of Mg elements on the density, microstructure, mechanical property and corrosion behavior of Zn-based alloy additively manufactured parts was investigated. Experiment results demonstrate that the density of pure Zn-based additively manufactured parts under optimal parameters can be up to 96.7%. With the same parameters, Zn-3Mg alloy was prepared by SLM additive manufacturing technology to obtain additively manufactured parts of Zn-3Mg alloy with the density of 96.0%. Compared with pure Zn, the average grain size in horizontal sections of additively manufactured parts added with 3 wt% Mg reduces from about 21.1 μm to about 2.1 μm and columnar crystals in vertical sections are transformed into equiaxed crystals. The microhardness of Zn-3Mg alloy is 2.6 times higher than that of pure Zn and tensile strengths in both the horizontal and vertical directions of Zn-3Mg alloy are twice as high as that of pure Zn. Moreover, the yield strength of Zn-3Mg alloy under compressive load is more than three times higher than that of pure Zn. After immersing pure Zn and Zn-3Mg alloy in simulated body field (SBF) for 7 days, their corrosion rates tend to be stable, i.e. about 0.13 and 0.09 mm·year−1 respectively, that is, the corrosion rate of Zn-3Mg alloy is about 70% that of pure Zn.