The structure and mechanical properties of biomedical magnesium alloy Mg–1%Zn–0.2%Ca

It is known, that magnesium-based alloys are the appropriate materials to be used as biodegradable metals to produce new-generation medical implants. Magnesium can decompose in the human body during the healing process. If dissolution is controlled, there is no need in additional operation for implant removal after healing completion. Particularly, Mg-Zn-Ca alloys are considered the most appropriate biodegradable metal implants due to their biocompatibility. In the Mg-Zn-Ca alloys, the addition of Zn and Ca as alloying elements can improve the mechanical properties and increase the corrosion resistance compared to pure Mg without affecting biocompatibility. The work covers the study of the structure and mechanical properties of the magnesium Mg-1%Zn-0.2%Ca alloy after severe plastic deformation (SPD). The research of the structure was carried out using scanning and transmission electron microscopy. The study of mechanical properties was carried out by measuring microhardness and tension tests. The study shows that applying the equal channel angular pressing (ECAP) method and additional treatment with the severe plastic deformation (SPD) method to the Mg–1%Zn–0.2%Ca alloy leads to the formation of the ultra-fine grain (UFG) structure with the average grain size of less than 1 micron. The authors identified that, as a result of strong refinement of the magnesium alloy grain structure, the ultimate strength increases twice up to 283 MPa compared to the homogenized state, when the ultimate strength is 125 MPa. At the same time, in the UFG state, the plasticity significantly decreases up to 3 %.