The Study On The Biodegradable Mg-Zn Alloys And Composites

Magnesium (Mg) alloys and Mg matrix composites are considered as promising biodegradable orthopedic implants due to their good biocompatibility and degradability. Their application in clinical medicine instead of stainless steel, titanium and other traditional medical metal biomaterial can effectively avoid the secondary surgery. However, the high corrosion rate and the low mechanical properties of biological safety magnesium alloy badly confined their application in clinical. Therefore, it's one of the main approaches to develop Mg-based biomaterials with good corrosion resistance and high strength for the application of Mg in biomedical engineering.In this work, we smelted the Mg-3.0wt%Zn, Mg-3.0wt%Zn-0.8wt%Zr and Mg-3.0wt%Zn-1.0wt%Ca alloys. The effects of trace elements Zr and Ca on the microstructure and properties of Mg-Zn alloy system were investigated by microstructure observation, mechanical testing and in-vitro corrosion evaluations. The influence of hot extrusion with two extrusion ratio on the microstructure and properties of Mg-Zn-Zr alloy were also investigated. We also smelted xβ-TCP/Mg-3.0Zn-0.8Zr(x=0.5, 1.0, 1.5 in wt. %) and yn-HA/Mg-3.0Zn-1.0Ca(y=1.0, 3.0 in wt. %) composites and studied the influence of adding nano-particle reinforcement on the microstructure and properties of the composites. The results are summarized as follows:1. The addition of trace Zr or Ca could significantly refine the grains of Mg-Zn alloy system and improve its mechanical properties and corrosion resistance.2. Hot extrusion can refine the grain of Mg alloys, optimize the microstructure and properties of alloys. Furthermore, the as-extruded Mg-Zn-Zr alloy with a large extrusion ratio exhibited superior properties.3. Theβ-TCP and n-HA particles uniformly distributed in Mg-Zn-Zr and Mg-Zn-Ca alloys can refine the grains of Mg alloys. The mechanical and corrosive properties in the SBF of 1.0wt%β-TCP/Mg-3.0wt%Zn-0.8wt%Zr and 1.0wt%n-HA/Mg-3.0wt%Zn-1.0wt%Ca composites were improved compared with Mg alloys.