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 μ m to about 2.1 μ m 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.