Effect of Mn addition on the microstructure, mechanical, and corrosion properties of an extruded biodegradable Zn-0.2Mg alloy

In this study, the effect of Mn addition on microstructural evolution, mechanical properties, and biocorrosion behaviors of as-extruded Zn-0.2 Mg alloy as candidates for degradable biomaterials were investigated. The microstructural observations indicated that the addition of Mn element significantly refined α-Zn grains, and the average size decreased from 17.23 μm to 7.14 μm. Moreover, Mn-rich intermetallic precipitated alongside eutectic Mg2Zn11 phases. A result of electron backscattered diffraction indicated that manganese has caused grains to rotate 19°, facilitating the activation of non-basal slip as the Schmid factor increases. Mechanical test results showed that the yield strength (YS), ultimate tensile strength (UTS), and elongation (El) of Zn-0.2Mg-0.5Mn alloy is improved by 35.92%, 31.51%, and 6.65%, respectively, compared with Zn-0.2 Mg alloy. The main mechanisms responsible for the improvement of mechanical properties were higher volume fraction of the particles, grain refinement, texture modification, and deformation twining formed by Mn addition. The electrochemical test in SBF solution at human body temperature revealed that the corrosion rate of Mn-containing alloy increased from 0.664 mm/year to 0.87 mm/year compared to the base alloy. It is evident from these results that the Zn-0.2Mg-0.5Mn alloy has a great deal of potential as a cardiovascular stent material