Microstructure and properties of biodegradable Mg-Zn-Y-Nd alloy micro-tubes prepared by an improved method

In this study, Mg-Zn-Y-Nd alloy micro-tubes with an outer diameter of phi 2.46 mm and a wall thickness of 0.14 mm were successfully prepared using an improved technique including hot extrusion with water cooling, multi-pass cold drawing and final annealing treatment. The outer diameter error, inner diameter error and wall thickness error of the cold drawn micro-tubes were 0.58%, 0.36% and 3.43%, respectively. After final annealing at 350 degrees C for 60 min, the micro-tubes showed refined microstructure with an average grain size of 8.6 mu m, a weak texture of the rare earth texture or recrystallization texture, and homogeneously distributed fine second phase particles. The annealed micro-tubes exhibited significantly improved mechanical properties with a yield strength of 240.1 +/- 6.0 MPa, an ultimate tensile strength of 319.9 +/- 6.0 MPa and a breaking elongation of 22.2 +/- 1.0%. Meanwhile, the typical characteristic of ductile morphology could be observed for the fractured specimens. In addition, the annealed micro-tubes also had better corrosion resistance and showed a uniform corrosion morphology. (C) 2020 Elsevier B.V. All rights reserved.