Preparation And Research On Microstructure And Mechanical Properties Of New High Performance Magnesium Alloys

Recently, light-weight structural materials, especially high-strength Magnesium alloys, have received extensive attention in various fields. Magnesium, as one of the essential trace element of human body, is biodegradable and biocompatible. Compared with numerous metal hard tissue implant materials having been put into clinical use, Magnesium alloys which have good mechanical properties are especially attractive in osteosynthesis due to the fact that the density and Young’s modulus of Magnesium are most closed to that of human bone. And there is no need to remove magnesium implant after the bones are healed, avoiding a second operation and reducing the burdens on both the patient and the health care system. Therefore, suitable magnesium alloys for applications in osteosynthesis should be developed to be widely used.Considering the role of alloying elements in field of the biomedical and materials science, new Mg-2Zn-0.5Ca-xMn alloy was designed. Magnesium alloys were prepared by melting method, in the process of which the resistance furnace was sealed and Argon was used for protection.According to Mg-Zn and Mg-Ca binary phase diagrams and Mg-Zn-Ca ternary phase diagram, three different heat treatment methods were made in order to strength magnesium alloys. Solution and aging treatment was ensured as the pre-treatment process of hot extrusion through a comparative analysis of microstructure of alloys after the three heat treatment methods. Finally, for the sake of enhancing the strength and ductility more effectively, hot extrusion of magnesium alloys was conducted to obtain medical magnesium alloys with high performance. Microstructure, phase composition, fracture morphology and mechanical properties testing of Mg-2Zn-0.5Ca-xMn alloys as cast, heat treatment and extruded were analyzed by means of optical microscope, scanning electron microscope, XRD diffraction (XRD) and CSS electronic universal testing machine to obtain initial performance parameters of designed alloys.Based on the obtained parameters, studied the effect of Mn content, heat treatment and hot extrusion on microstructure and mechanical properties of Mg-2Zn-0.5Ca-xMn alloys and explored the evolution and deformation mechanism of microstructure, mechanical properties and fracture behavior of Mg-Zn-Ca-Mn alloy during the solidification, heat treatment and hot extrusion process.