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

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 alpha-Mg, Mg12Ce and CeMgZn2, while after adding 0.5 wt-% Ca to Mg-2.2Zn-3.7Ce alloy, IM1 (Ca3MgxZn15-x) (4.6 <= x <= 12) phase was detected. Further addition of Ca to 6 wt-% resulted in forming Mg2Ca besides alpha-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.