Microstructure evolution, mechanical properties and corrosion behavior of biodegradable Zn-2Cu-0.8Li alloy during room temperature drawing

Biodegradable Zn-based alloys exhibit promising application prospects due to their suitable degradation rates and acceptable biocompatibility. However, unstable mechanical properties during room-temperature storage limit their application potential. In this study, Zn-2Cu-0.8Li (wt%) alloy wires with excellent and stable mechanical properties were prepared by hot extrusion followed by multi-pass cold drawing. For the as-extruded Zn-2Cu-0.8Li alloy of a [1¯21¯0]//ED texture, (Li, Cu)Zn4 phase (volume fraction: 84.4 ± 2.4%) is found to be the matrix, and the remaining phase is Zn-based solid solution (η-Zn phase). During cold drawing, the (Li, Cu)Zn4 phase was continuously elongated, and its original texture gradually evolved into intensive [011¯0]//DD fiber texture. In contrast, the η-Zn phase exhibits an evidently refined grain structure and weakened texture due to dynamic recrystallization (DRX). Accordingly, the ultimate tensile strength was significantly improved from348.1 ± 3.1 MPa (as-extruded rod: Ø 6 mm) to 450.3 ± 8.7 MPa (as-drawn wire: Ø 3 mm), with the elongation decreasing from 37.1 ± 2.1% to 29.5 ± 1.3%. After 6-month natural aging, the as-drawn wire showed desirable mechanical stability, with basically unchanged mechanical properties. The corrosion rate of as-drawn wire with a diameter of 3 mm in c-SBF solution exhibits a 46% increase (from 212.07 ± 10.73 μm/year to 309.81 ± 16.53 μm/year) after cold drawing. Given the excellent mechanical properties and suitable corrosion rate, the Zn-2Cu-0.8Li wires are proposed as a promising material for biodegradable implants.