Microstructure, mechanical and bio-corrosion properties of as-extruded Mg-Sn-Ca alloys

The as-extruded Mg-Sn-Ca alloys were prepared and investigated for orthopedic applications via using optical microscopy, scanning electron microscopy, X-ray diffraction, as well as tensile, immersion and electrochemical tests. The results showed that, with the addition of 1% Sn and the Ca content of 0.2%-0.5%, the microstructure of the as-extruded Mg-Sn-Ca alloys became homogenous, which led to increased mechanical properties and improved corrosion resistance. Further increase of Ca content up to 1.5% improved the strength, but deteriorated the ductility and corrosion resistance. For the alloy containing 0.5% Ca, when the Sn content increased from 1% to 3%, the ultimate tensile strength increased with a decreased corrosion resistance, and the lowest yield strength and ductility appeared with the Sn content of 2%. These behaviors were determined by Sn/Ca mass ratio. The analyses showed that as-extruded Mg-1Sn-0.5Ca alloy was promising as a biodegradable orthopedic implant.