Fabrication and characterization of biodegradable Zn-Cu-Mn alloy micro-tubes and vascular stents: Microstructure, texture, mechanical properties and corrosion behavior

Zinc (Zn) alloys are a promising biodegradable material for vascular stent applications. This study aimed to fabricate biodegradable Zn-2.0Cu-0.5Mn alloy micro-tubes and vascular stents with high dimensional accuracy and suitable mechanical properties, and to investigate their microstructure, texture, mechanical properties and corrosion behavior. The micro-tubes and vascular stents were successfully fabricated by a combined process of extrusion, drawing, laser cutting and electrochemical polishing. The microstruc-tures of as-extruded and as-drawn micro-tubes consisted of Zn matrix with near-equiaxed grains (aver-age grain size: similar to 2 pm) and second phases of epsilon (CuZn4) and MnZn13 with different sizes. The texture evolved from basal planes approximately paralleling to deformation direction for as-extruded micro-tube to approximately perpendicular to deformation direction for as-drawn micro-tube, because predominant deformation mechanisms changed from basal < a > dislocation slip during tube extrusion to prismatic < a > dislocation, pyramidal < c + a > dislocations, and { 10 1 over bar 2 } twins during tube drawing. As-drawn micro -tube exhibited suitable mechanical properties with an ultimate tensile strength of about 298 MPa and elongation of about 26% as a stent material. Moreover, the processed stent with a thickness of about 125 pm possessed sufficient radial strength of about 150 kPa and good balloon expandability. In addi-tion, as-drawn tube exhibited an in vitro corrosion rate of about 158 pm/year with a basically uniform corrosion morphology. These results indicated that biodegradable Zn-2.0Cu-0.5Mn alloy is a promising vascular stent material candidate, and the procedure for processing the micro-tube and stent is practical and effective.

Automated summary

This study successfully fabricated biodegradable zinc alloy micro-tubes and vascular stents with suitable mechanical properties and corrosion behavior, indicating them as promising candidates for vascular stent applications.