Simultaneously improving the mechanical property and corrosion resistance of extruded biomedical Mg-3Zn alloy by forming in-situ MgO

In-situ MgO reinforced Mg–3Zn composites were prepared by high-shear melt stirring technology through adding CaO particles. The effects of CaO contents on the microstructure and properties, including mechanical properties and corrosion resistance, were investigated systematically. The microstructure showed that the CaO particles would react with Mg melt and form MgO nanoparticles. Moderate CaO content could react completely with Mg melt, however, when CaO content was 1.0 wt.%, aggregation was likely to occur and part of CaO would be remaining. Moreover, it was revealed that the in-situ MgO could significantly promote the grain refinement of the material. There was an obvious improvement of mechanical properties for all the composites after adding CaO particles. Thereinto, Mg–3Zn-0.7CaO composite exhibited the best tensile yield strength of 346.3 ± 4.1 MPa and improved 145% compared with that of Mg–3Zn alloy (141.6 ± 6.5 MPa). Besides, the corrosion resistance of the composites was also improved after forming MgO from the results of electrochemical polarization curves and the Mg–3Zn-0.7CaO composite also displayed the lowest current density of 4.7 μA/cm 2 . The strengthening mechanism for the mechanical property and corrosion resistance of the composites were discussed.