Effect of Extrusion Ratio on Mechanical and in Vitro Degradation Properties of Mg-Zn-Ca Microtubes for Biodegradable Vascular Stents

Abstract

Magnesium (Mg) has emerged as a promising biomaterial, with considerable potential for utilization in biomedical applications. However, Mg alloys are confronted with specific challenges, including rapid biodegradation, low mechanical strength, and processing difficulties. It is thus of paramount importance to develop high-performance Mg alloys and the associated processing techniques with the objective of enhancing their overall properties for utilization in biomedical applications. This study examines the impact of extrusion ratio on the mechanical properties and in vitro degradation behavior of Mg-1Zn-0.1Ca (ZX101) microtubes for biodegradable vascular stents. Two-step direct extrusion was employed to fabricate microtubes with outer diameters of 3.5 mm and 2.1 mm and wall thicknesses of 250 µm and 200 µm, respectively. As the extrusion ratio increased, the dimensional accuracy exhibited an improvement for the outer diameter, whereas a decline was observed for the inner diameter. As the extrusion ratio increased from 57:1 to 121:1, the tensile properties of the extruded ZX101 microtubes were enhanced by grain refinement, despite a concurrent weakening of the basal texture. Furthermore, an increase in the extrusion ratio led to an accelerated biodegradation rate. These findings contribute to the pivotal interplay between microstructure, mechanical properties, and biodegradation in the design of Mg-based biodegradable stents.