Tailoring the Microstructure and Enhancing the Properties of Degradable Mg-Y-Zn Alloy with Various Y Contents

In this study, the microstructure, mechanical properties, and corrosion behavior of extruded Mg-Y-0.5Zn alloys with varying Y contents (0.5~3.0 wt%) were systematically investigated. The results demonstrate that by increasing the Y content from 0.5% to 3.0%, the grain sizes of four alloys are 11.27 μm, 11.90 μm, 15.26 μm, and 13.65 μm. The secondary phases of all four alloys consist of granular Mg24Y5 and fine Mg12YZn, and the total volume fraction of these precipitates increased. Correspondingly, both microhardness and strength are enhanced, while ductility decreases. The microhardness increases from 57.1 HV to 61.7 HV, the tensile yield strength (TYS) improves from 103.8 MPa to 155.4 MPa, and the ultimate tensile strength (UTS) rises from 211.4 MPa to 235.9 MPa. Regarding corrosion performance, the extruded Mg-1Y-0.5Zn alloy exhibits the best corrosion resistance based on both in vitro immersion tests and electrochemical measurements. A uniform and dense corrosion product layer is observed on the surface of Mg-1Y-0.5Zn alloy, leading to the lowest corrosion rate of 0.36 mm/y, while loose and micro-cracked corrosion product layers are formed on other alloys. In addition, cytotoxicity test shows that the relative cell proliferation rates of the four extruded alloys were 121.41%, 123.7%, 117.96%, and 112.86%, indicating good biocompatibility.