Effect of Mg Content on the Structure, Properties and Cytotoxicity of Biodegradable Zn-Fe-Mg Alloys

Interest in biodegradable materials for temporary implants based on zinc alloys has been growing annually. The Zn-Fe-Mg alloys are of special interest, as each of its constituent elements is independently considered as biodegradable metallic material. This study presents a comprehensive investigation of the Zn-1%Fe-1%Mg and Zn-1%Fe-5%Mg alloys subjected to high-pressure torsion. A comparative analysis was conducted on the microstructure of the alloys in both as-cast and deformed states, highlighting differences in their phase composition, strength and cytotoxicity. When the magnesium content exceeds 3 wt.%, an additional phase (MgZn2) precipitates alongside the existing Mg2Zn11 phase. Deformation processing of the Zn-1%Fe-1%Mg alloy effectively reduces its brittleness and promotes a more homogeneous distribution of the Mg2Zn11 eutectic throughout the sample volume. In contrast, the Zn-1%Fe-5%Mg alloy retains excessive brittleness even after deformation. The addition of magnesium was found also to accelerate corrosion rates. Nevertheless, the strength, corrosion, and cytotoxicity properties of the Zn-1%Fe-1%Mg alloy meet the requirements for biodegradable materials.