A combined strategy to enhance the properties of Zn by laser rapid solidification and laser alloying

The orthopedic application of Zn is limited owing to the poor strength and low plasticity. In this study, a novel strategy by combining rapid solidification obtained by selective laser melting (SLM) and alloying with Mg was proposed to improve the mechanical properties of Zn. The microstructures, mechanical properties, as well as in vitro cytocompatibility of SLM processed Zn-xMg (x = 0-4 wt%) were studied systematically. Results shown that SLM processed Zn-xMg alloys consisted of fine equiaxed alpha-Zn grains with homogeneously precipitated Mg2Zn11 along grain boundaries. More importantly, the grains size of alpha-Zn was decreased from 104.4 +/- 30.4 mu m to 4.9 +/- 1.4 mu m with Mg increasing. And Mg mainly dissolved in alpha-Zn developing into supersaturated solid solution due to rapid solidification effect. As a consequence, the ultimate tensile strength and elongation were enhanced by 361% and 423%, respectively, with Mg containing up to 3 wt%. Meanwhile, alloying with Mg enhanced the corrosion resistance of Zn, with the degradation rate decreasing from 0.18 +/- 0.03 mm year(-1) to 0.10 +/- 0.04 mm year(-1). Furthermore, SLM processed Zn-xMg exhibited good biocompatibility. This research suggested that SLM processed Zn-3Mg alloy was a potential biomaterial for orthopedic applications.