Processing and Characterization of Mg Microtubes for Biodegradable Vascular Stents

Magnesium (Mg) alloys have attracted increasing attention as potential metallic biomaterials for temporary biodegradable implants in orthopedic and vascular applications due to their mechanical, electrochemical, and biological properties. However, Mg scaffolds still face some challenges such as high degradation rate, low mechanical properties, difficult fabrication method. Processing and alloying are key approaches to improving the comprehensive properties of Mg alloys for biomedical applications. This study investigated the microstructure, texture and mechanical properties of Mg-Zn-Ca (MZ01) microtubes fabricated by two-step extrusion for biodegradable vascular stents. Direct two-step extrusion at 400 °C produced seamless MZ01 microtubes with outer diameters of 3.5 and 2.5 mm, wall thickness of 250 µm, and maximum length of 2 m. Dimensional accuracy based on roundness improved as outer diameter decreased. Increasing the extrusion ratio made grains refiner and weakened texture intensity. The mechanical behavior of MZ01 microtubes was analyzed with respect to changes in microstructure and texture. Grain boundary strengthening and texture hardening were involved in the plasticity of as-extruded MZ01 microtubes.