Novel Zn-Mg-Zr Ternary Alloys For Biodegradable Medical Implants

Biodegradable metals with biodegradability and biomechanical properties are currently the hot topics of research on biomaterials.The standard electrode potential of zinc is between that of Mg and Fe,and has excellent biocompatibility,so zinc has been regarded as the most promising biodegradable metal materials.This paper designed and prepared different composition of Zinc Magnesium zirconium ternary alloy.The comprehensive properties of the alloy were evaluated by means of metallography,hardness,tensile test,electrochemical test and immersion test,and the strengthening mechanism of alloying elements Mg and Zr was compared.Microstructure of Zn-Mg-Zr Ternary Alloy shows that the microstructure of the alloys is mainly composed ofα-Zn phase andα-Zn/Mg₂Zn₁₁ eutectic,the Zr element mainly exists in the form of polygonal zirconium rich phase inlaid in the grain boundary.Tensile and hardness tests show that the hardness and tensile strength of the Ternary alloys monotonically increase with the content of Mg,the increase of Zr also increases the strength of the alloy.The mechanical properties of Zn-3Mg-0.5Zr are the best with the hardness of 178HV,the tensile strength of 193.47±15.96MPa.Electrochemical test of the alloys shows that the corrosion resistance of the Zn-Mg-Zr ternary alloys is between pure Zn and Zn-2Mg.The increase of Mg element can accelerate the corrosion rate of the alloys,but the Zr element slightly improves the corrosion resistance of the alloy.30-days immersion test in SBF showed that the corrosion resistance of Zn-3Mg-0.5Zr was the slowest at 44.82μm/year.The results of SEM&EDS after immersion test show intergranular corrosion.Zr element can significantly improve the Ca:P ratio of the alloys’surface,which indicating the improvement of the biological activity.