Evaluation of mechanical and corrosion properties of Mg-9Li-Zn alloy in simulated body fluid (SBF) solution as a biodegradable implant material

Abstract

The mechanical properties of Mg are similar to human bone and can decompose naturally, making Mg suitable for biodegradable implant materials. However, the high corrosion rate of Mg limits its practical applications. One way to solve this problem is to add 9 wt% Li and 1 wt% Zn to pure magnesium to increase formability and corrosion resistance. The experiment was initiated by homogenizing Mg-9Li-Zn at 350°C for 3 hours to obtain a more uniform microstructure. The microstructure, mechanical properties, and corrosion properties of Mg-9Li-Zn were investigated to determine the alloy’s biodegradable behavior. The OM and XRD tests showed that the Mg-9Li-Zn microstructure is composed of α-Mg and β-Li phases. On the other hand, the SEM test showed the presence of MgO and ZnO particles in Mg-9Li-Zn. The mechanical properties of Mg-9Li-Zn studied by tensile and microhardness tests showed higher elongation value and lower strength than that of pure Mg. The corrosion properties were obtained from polarization and immersion testing for 2 weeks in the revised SBF solution. Mg-9Li-Zn corroded at a lower rate than pure Mg in both polarization and immersion tests. As a result, in the presence of 9 wt% Li and 1 wt% Zn in pure Mg, the microstructure and mechanical properties changed, and the corrosion rate decreased.