Biodegradable Mg-Y and Mg-Li Alloys with the Addition of Ca and Zn for Medical Applications

The study describes structure characteristics as well as mechanical properties, corrosion behavior and biocompatibility of Mg-Y and Mg-Li alloys with 0.2% Ca, 1% Ca and 1% Zn cast into permanent molds. The structure showed a significant effect of the amount of alloying additives on the morphology of phases occurring mainly at the grain boundaries. Alloy composition also affects the possibility of grain structure refinement. The mechanical properties obtained the highest level in alloys with the addition of 1% Zn and 0.2% Ca. The results of biodegradation tests carried out in Ringer's solution showed that the lowest dissolution rate had the alloys with low Ca content. High Ca content raised the content of the Mg2Ca phase in the alloy, which acted as a catalyst of the grain boundary corrosion. The examination of Mg alloys carried out under sterile conditions at 37 degrees C after 144 h of the test in alpha-MEM solution has proved a high biocompatibility of these alloys when containing additions of Li, Ca and Zn.