ABSTRACT
Magnesium (Mg)-Calcium (Ca) binary alloys are commercially available as a master alloy to fabricate other ternary or quaternary alloys. Mg-Ca alloys with a large range of Ca addition were fabricated during their development as biomaterials. Metallurgy is a low-cost and effective way to produce as-cast alloys, and the Ca in Mg-Ca alloys can be introduced with Mg-Ca master alloys. The degradation of Mg-Ca alloys results in hydrogen release and the precipitation of corrosion products. The Mg-Ca binary alloys exhibited good biocompatibility and comparable mechanical property with natural bone in both in vitro and in vivo evaluations. A low amount of Ca in the Mg-Ca-Zr alloys can improve the strength due to the refinement of grain size and solid solution strengthening. The mechanical properties of the Mg-Ca-Sr alloys depend on the amounts and distribution of the secondary phases along the grain boundaries. In addition to the binary and ternary Mg-Ca alloys, quaternary and multielementary Mg-Ca alloys were studied as biodegradable metals.
