Fabrication and Characterization of Friction Stir-Processed Mg-Zn-Ca Biomaterials Strengthened with MgO Particles

Magnesium alloy composites play an important role in biomaterials field. In this study, a novel Mg-Zn-Ca matrix composite was reinforced by adding 1.0 wt.% MgO nanoparticles via the high shear casting process. Hereafter, friction stir processing (FSP) was used to achieve a good dispersion of MgO particles and improve the mechanical properties of the composites. After the preparation of the novel composite materials, varied characterization and performance test methods have been selected for comparison. The results illustrate that through FSP, the corresponding microstructure and properties of as-cast MgO/Mg-Zn-Ca composites were significantly modified, and the best combination of the key parameters is 1200 rpm and 60 mm/min for rotational velocity and traveling speed, respectively. After the optimized FSP treatment, the grains size in FSP-processed composites were refined by 42%, to reach 1.04 μm. Due to the grain refinement and the redistribution of MgO particles, the hardness of the FSP-processed MgO/Mg-Zn-Ca composites were increased by 40%, to reach 101.2 HV. Further, it displayed excellent corrosion resistance as well as strength. Compared to the strengthening through grain refinement, the particle strengthening is more dominant based on the study. And meanwhile, the modified grains and added MgO particles are beneficial to the properties of the nugget zones.