Paper Title
Structural and Mechanical Properties Investigations in a New Biodegradable Mg-2.7Zn-1Ca-0.6Zr Alloy Processed By Extrusion And Heat Treated

Abstract
Magnesium and its alloys are the main biodegradable materials used for the production of biomedical devices, considering their high mechanical properties, high biocompatibility profile and their ability to be completely degraded in physiological environment. In this study, a new biodegradable magnesium alloy (Mg-2.7Zn-1Ca-0.6Zr) was produced and two advanced thermomechanical processing routes were designed and applied for the newly developed material. These routes are mainly consisting in extrusions at 400°C using various extrusion ratios, followed by two different heat treatments at 180°C and 250°C for 7 minutes, air cooling. The influence of processing parameters on microstructural and mechanical characteristics evolution was evaluated, all processed specimens being metallographically examined using scanning electron microscopy – secondary electron imaging (SEM-SE) and mechanically investigated in tensile and microhardness tests. Ultimate tensile strength, yield strength, maximum elongation to fracture and the average Vickers microhardness were determined and the fracture surfaces were also analyzed via SEM-SE. A significant improvement of ductility was revealed as a result of applying the final heat treatments after extrusion, with no major impact on strength and hardness characteristics obtained in hot plastic deformation. The optimum thermomechanical processing route for the new biodegradable magnesium alloy was also evaluated. Keywords - Magnesium Alloys, Extrusion, Heat Treatment, Microstructure, Mechanical Properties.