Nanostructuring of Zn–Li-based alloys through severe plastic deformation: Microstructure, mechanical properties, and corrosion behaviors

Abstract

To date, nanostructuring through plastic deformation has rarely been reported in biodegradable zinc (Zn) based alloys that have great potential in load-bearing conditions. Here, typical high-strength Zn–Li-based alloys were subjected to SPD processes, including equal channel angular pressing (ECAP) and high-pressure torsion (HPT), to achieve nanostructured microstructures. The effects of SPD on the microstructures, mechanical properties, and corrosion behaviors were generally investigated. The two SPD routes resulted in totally different microstructures. ECAPed samples processed at 150 ​°C exhibited a complicated multilevel structure (nm to μm) with mixed Zn equiaxed grains and lamellar-like eutectoid regions (Zn ​+ ​α-LiZn₄), and HPTed ones (25 ​°C) possessed a fully dynamically recrystallized (DRXed) microstructure with an average grain size below 0.4 ​μm. The tensile strength of the SPD samples could reach 500 ​MPa. Meanwhile, HPTed samples exhibited extraordinary fracture elongations higher than 100 ​%, because of a different grain boundary sliding deformation mechanism. HPTed samples and ECAPed samples displayed different corrosion patterns, and the former exhibited a much higher corrosion rate in Hank's solution, possibly due to the accelerated corrosion at grain boundaries. In summary, SPD is an efficient way to refine the microstructure of biodegradable Zn-based alloys, possibly improving their performances and clinical applications.