Characterisation and thermodynamic calculations of biodegradable Mg–2.2Zn–3.7Ce and Mg–Ca–2.2Zn–3.7Ce alloys

Abstract

In the present study, the effect of Ca (0.5–6 wt-%) content on the microstructure, phase formation, and mechanical properties and in vitro degradation behaviour of Mg–2.2Zn–3.7Ce alloys were investigated. Microstructural analysis and thermodynamic calculations also showed that Mg–2.2Zn–3.7Ce alloy contain α-Mg, Mg₁₂Ce and CeMgZn₂, while after adding 0.5 wt-% Ca to Mg–2.2Zn–3.7Ce alloy, IM1 (Ca₃Mg _x Zn_15−x ) (4.6 ≤ x ≤ 12) phase was detected. Further addition of Ca to 6 wt-% resulted in forming Mg₂Ca besides α-Mg, Mg₁₂Ce and IM1 with the absence of CeMgZn₂. The tensile strength and elongation of the Mg–Ca–2.2Zn–3.7Ce alloys increase with increasing Ca content up to 1.5 wt-%, while further addition of Ca to 6 wt-% has a reversed effect. Similarly, the degradation rate of the alloys increased first with increasing Ca content and then decreased.