Improvement of the mechanical properties and corrosion resistance of biodegradable β-Ca(PO)/Mg-Zn composites prepared by powder metallurgy: the adding β-Ca(PO) hot extrusion and aging treatment.

In this study, 10%β-Ca(PO)/Mg-6%Zn (wt.%) composites with Mg-6%Zn alloy as control were prepared by powder metallurgy. After hot extrusion, the as-extruded composites were aged for 72h at 150°C. The effects of the adding β-Ca(PO), hot extrusion and aging treatment on their microstructure, mechanical properties and corrosion resistance were investigated. The XRD results identified α-Mg, MgZn phase and β-Ca(PO) phase in these composites. After hot extrusion, grains were significantly refined, and the larger-sized β-Ca(PO) particles and coarse MgZn phases were broken into linear-distributed β-Ca(PO) and MgZn phases along the extrusion direction. After aging treatment, the elements of Zn, Ca, P and O presented a more homogeneous distribution. The compressive strengths of the β-Ca(PO)/Mg-Zn composites were approximately double those of natural bone, and their densities and elastic moduli matched those of natural bone. The immersion tests and electrochemical tests revealed that the adding β-Ca(PO), hot extrusion and aging treatment could promote the formation of protective corrosion product layer on the sample surface in Ringer's solution, which improved corrosion resistance of the β-Ca(PO)/Mg-Zn composites. The XRD results indicated that the corrosion product layer contained Mg(OH), β-Ca(PO) and hydroxyapatite (HA). The cytotoxicity assessments showed the as-extruded β-Ca(PO)/Mg-Zn composite aged for 72h was harmless to L-929 cells. These results suggested that the β-Ca(PO)/Mg-Zn composites prepared by powder metallurgy were promising to be used for bone tissue engineering.