Microstructure, mechanical and corrosion properties of novel quaternary biodegradable extruded Mg–1Zn–0.2Ca-xAg alloys

In the anastomotic surgery, the currently used degradable magnesium alloys are facing some bottleneck problems such as lower mechanical properties and slower degradation rate. In this study, the novel biodegradable extruded Mg–1Zn–0.2Ca-xAg (x = 0, 1, 2, 4) alloys will be developed and the corresponding microstructure, mechanical, and corrosion properties after Ag addition will be investigated. The results indicate that with the Ag addition, the grain size is refined due to fully dynamic recrystallization and Ag₁₇Mg₅₄ phase, an important strengthening phase, begin to be precipitated in the Ag-contained alloys. Due to the stronger solution strengthening and precipitation strengthening, the Mg–1Zn–0.2Ca-4Ag alloy attains the highest ultimate tensile strength among all the alloys. Moreover, Ag element also enhances the electrode potential of the matrix, reduces the susceptibility of pitting corrosion and accelerates the corrosion rate of the alloys by micro-galvanic corrosion between the second phases and the matrix from the analyses of corrosion products and 3D Volta potential map. As a result, 4Ag alloys attain the fastest degradation rate among all the alloys. Combing the mechanical and corrosion results, it can be seen that 4Ag alloys, as novel biodegradable magnesium alloys, can meet the requirement of anastomotic surgery preferably, exhibiting the better application prospects. (paper)