Effects of Sr on the microstructure, mechanical properties and corrosion behavior of Mg-2Zn-xSr alloys.

The effects of the addition of Sr on the microstructures, mechanical properties and bio-corrosion properties of Mg-2Zn alloys were investigated. Examination of the microstructures indicates that Sr addition promoted grain refinement and the formation of secondary phases. The results for the mechanical and corrosion property analyses show that the Mg-2Zn-0.2Sr alloy exhibited the best mechanical properties and bio-corrosion resistance. Notably, fine grain structure can promote strength and ductility, while the excessive secondary phases Mg17Sr2 resulted in the degradation of mechanical performance. Moreover, corrosion resistance could be improved by reducing the impurity concentrations and forming a denser corrosion product layer, while the secondary phases accelerated the corrosion process by forming micro-galvanic couples with the Mg matrix. It is considered that the addition of Sr (0.2%) represents the main contributing factor to these improved properties. The Mg-2Zn-0.2Sr alloy provides excellent strength and corrosion resistance for biomedical applications.