Effect of Gd on Dynamic Recrystallization Behavior of Magnesium During Hot Compression

Abstract

Dynamic recrystallization (DRX) behavior of two binary Mg–0.5Gd and Mg–1.5Gd alloys and pure Mg were studied by hot compression in the temperature range of 300–450 °C to explore the role of Gd on DRX grain size refinement and kinetics. The dependency of DRX grain size on the Gd content during hot compression was quantified and expressed based on the Zener–Hollomon parameter. While the exponent of the Zener–Hollomon parameter was obtained as − 0.118 independent of the Gd content, the proportionality constant varied by Gd concentration. The developed expression revealed significant reduction in the DRX grain size of the Mg–Gd alloys. The volume fraction of dynamically recrystallized grains was calculated by applying the Johnson–Mehl–Avrami–Kolmogorov type model, which resolved the faster kinetics for DRX of the Mg–1.5Gd alloy compared to ones for the Mg–0.5Gd alloy and pure Mg. The higher driving pressure for DRX of the Mg–1.5Gd alloy was justified based on dislocation density measurements at the onset of DRX through the Williamson-Hall method. The role of Gd on dynamic recrystallization behavior of Mg during hot compression was studied. A linear relationship between the DRX grain size and Gd content was developed and dislocation density of the binary Mg-Gd alloys and pure Mg at the onset of DRX during hot compression was measured.