Influence of Sr on microstructure evolution, mechanical and corrosion properties of extruded Mg-2Zn-0.5Ca alloy

Degradable Mg-Zn-Ca alloys with Sr addition were prepared by vacuum melting and hot extrusion. Effect of Sr on microstructure, mechanical and corrosion properties of hot extruded Mg-2Zn-0.5Ca-xSr (x = 0, 0.5, 1.0) alloys was investigated. The results show that Sr addition into Mg-2Zn-0.5Ca alloys produced significant grain refinement in ingots and obvious texture weakening effects in extruded bars. The ultimate compressive strength increased as the Sr content increased, while the ultimate tensile strength increased firstly and then declined with the increasing of Sr content. Electrochemical tests indicated the corrosion current density of the surface parallel to extrusion direction (ED) was much lower than that of the surface perpendicular to ED. In-vitro immersion tests demonstrated the increase in the pH of solution and weight loss of Mg-2Zn-0.5Ca-0.5Sr alloy remain the lowest during immersion tests. The best comprehensive property was obtained in Mg-2Zn-0.5Ca-0.5Sr alloy, which has the largest strength and the best corrosion resistance.