Investigation on Microstructures and Mechanical Properties of Extruded Biodegradable Zn-1Mg-xZr (x = 0−0.4 %) Alloys

Abstract

In this work, Zn-1Mg-xZr alloys were cast, annealed and hot-extruded to investigate the microstructures and/or mechanical properties. The results show that, besides the primary Zn-rich dendrites and lamellar eutectic Zn + Mg2Zn11 mixture, the addition of Zr produces extra block- or bar-like Zn22Zr intermetallic compounds in the as-cast Zn-1Mg-xZr alloys. The annealing process results in that the interdendritic eutectic mixture changes from lamellar morphology to discrete Mg2Zn11 particles. The hot extruding process seriously deforms the primary Zn-rich crystals (with twinning inside), and breaks the Mg2Zn11 and Zn22Zr intermetallic compounds into small particles. Adding Mg and Zr to pure Zn significantly improves the micro-hardness, ultimate tensile strength (UTS), tensile yield strength (TYS) and compression yield strength (CYS). The addition of Zr to binary Zn-1Mg alloy slightly improves the micro-hardness, UTS, TYS and CYS, but contributes more to the elongations. The modification of the mechanical properties is related to the change of the microstructures due to the addition of alloying elements and hot-working deformation.