Microstructure, mechanical properties, cytotoxicity, and bio-corrosion of micro-alloyed Mg–xSn–0.04Mn alloys for biodegradable orthopedic applications: Effect of processing techniques

Abstract

Magnesium alloys have great potential for load-bearing biodegradable orthopedic implants. The mechanical properties and corrosion resistance depend on alloy composition and processing technique. Presently, the effect of processing techniques on the properties of Mg alloys containing small additions of Sn and 0.04Mn is investigated. Mg–xSn–0.04Mn alloys (x = 0.25 and 1.53wt%) were prepared by casting, heat treatment, hot extrusion, and hot rolling. Microstructure was investigated by optical microscopy, SEM, and XRD. The type, size, and volume fraction of precipitates were found to play the major role in determination of mechanical properties and rate of dissolution in Hank’s solution. A considerable rise in strength, ductility, and reduction in dissolution rate were obtained after thermomechanical treatment based on grain size, volume fraction, and distribution of precipitates. Extruded Mg–1.53Sn–0.04Mn alloy exhibited the best combination of strength, ductility and biodegradability by exhibiting a strength of 219.6 MPa, elongation of 7.9%, and corrosion rate of 0.71 mm/y, indicating that it is indeed a promising candidate for biodegradable orthopedic applications.