Effects of extrusion parameters on the microstructure, corrosion resistance, and mechanical properties of biodegradable Mg-Zn-Gd-Y-Zr alloy

The effects of the extrusion temperature and extrusion ratio on the microstructure, corrosion resistance, and mechanical properties of Mg-Zn-Gd-Y-Zr alloy were investigated. The dynamically recrystallized grain sizes were found to increase with increasing temperature at a given extrusion ratio. At a smaller extrusion ratio, the alloys consist mainly of a bimodal grain structure. Although these have better ultimate tensile strength (UTS) and yield strength (YS), their elongation (EL) and corrosion resistance are not as good as those of the alloys with a larger extrusion ratio extruded at the same temperature. When the extrusion temperature reaches the higher range of 340-380 degrees C with an extrusion ratio of 12, the alloy has little bimodal structuring. The alloy extruded at 340 degrees C with an extrusion ratio of 12 had a uniform microstructure and exhibited relatively good corrosion resistance in addition to having good mechanical properties. The ways in which the mechanical properties of this alloy varied with the duration of corrosion through immersion in simulated body fluid were also studied. The rate of decline in the EL was significantly greater than that in the YS, and these were found to have half-life values of 20 days and 51 days, respectively. (c) 2021 Elsevier B.V. All rights reserved.