Mechanical Properties and Corrosion Behavior of Biodegradable Mg-0.5Zr-0.5Ca-xZn Magnesium Alloys

Mechanical properties and in vitro corrosion behavior of biodegradable Mg-0.5Zr-0.5Ca-xZn alloys in the simulated body fluid (SBF) solution are investigated. Zinc addition leads to a remarkable grain refinement in the as-cast condition, as well as the formation of Ca2Mg6Zn3 and Mg7Zn3 compounds. As a result, the lean Mg-0.5Zr-0.5Ca-1Zn alloy shows the best combination of mechanical properties with an ultimate tensile strength (UTS) of 182 MPa, total elongation of 9.5%, and tensile toughness of 13 MJ m(-3), which reveals approximate to 80%, 72%, and 190% improvements compared to those obtained for the Mg-0.5Zr-0.5Ca alloy, respectively. This sample also exhibits improved corrosion behavior, where a decrease in the corrosion current density (i(Corr)) is recorded via the addition of 1 wt% Zn. However, higher Zn additions result in the formation of a quasi-continuous eutectic network with the consequent deterioration of tensile properties and increased effect of microgalvanic couples. The extreme grain refinement induced by the dynamic recrystallization (DRX) remarkably improves the overall mechanical properties of the hot extruded alloy but increased the i(Corr). Accordingly, the properties of Mg-0.5Zr-0.5Ca alloys can be tailored for biomedical applications via Zn addition and thermomechanical processing.