Investigation on Composition, Mechanical Properties, and Corrosion Resistance of Mg-0.5Ca-X(Sr, Zr, Sn) Biological Alloy

Four nontoxic biological alloys, Mg-0.5Ca-1Sr-4Zr (Alloy 1), Mg-0.5Ca-1Sr-1.5Zr (Alloy 2), Mg-0.5Ca-3Sr-1.5Zr (Alloy 3), and Mg-0.5Ca-1Sr-0.5Sn (Alloy 4), were prepared by vacuum smelting, gravity casting, and hot rolling. The composition and microstructureof the alloys were investigated by optical microscope, X-ray fluorescence spectrometer (XRF), X-ray diffraction (XRD), scanningelectron microscope (SEM), and energy dispersion spectroscopy (EDS). The mechanical properties and corrosion behaviors of thealloys in Hank’s solution were studied. Results showed that a large amount of fine and uniformly distributed second-phase particles(Zr, Mg17Sr2, and CaMgSn) was observed in four alloys obtained after rolling and alloying. The segregation of Zr in alloys wasobserved in EDS image, and chemical analysis showed that there was macrosegregation of the elements in the alloys. Furthermore,Mg17Sr2phases in the Mg-0.5Ca-1Sr-0.5Sn alloy homogenized the distribution of CaMgZn phases. The comprehensive mechanicalproperties of four newly designed rolled alloys were much higher than those of pure Mg, and the compressive strength of thealloys was more than twice as high as that of pure magnesium. The Mg-0.5Ca-1Sr-0.5Sn alloy released the least hydrogen in Hank’ssolution, which was lower than that of pure magnesium. Electrochemical test results in Hank’s solution further showed that theMg-0.5Ca-1Sr-0.5Sn alloy had delayed corrosion and lowest𝐼corrwhich was 25% of that of pure magnesium. Biological experimentsresults showed that the Mg-0.5Ca-1Sr-0.5Sn alloy had better biocompatibility and optimal potential for bone substitute material