Abstract
In this study, a Mg-9Gd-4Y-2Zn-0.5Zr (wt.%) alloy was subjected, after solution treatment, to hot compression deformation at different temperatures (350 °C, 400 °C and 450 °C) and different strain rates (0.001 s−1, 0.01 s−1, 0.1 s−1 and 0.5 s−1) on a Gleeble-3800 thermal simulator. The evolution of the stress–strain curves under different conditions was compared. The changes in microstructure caused by the different deformation parameters and the change law of the long-period stacking-ordered (LPSO) phase during compression were observed and analyzed by optical microscope (OM) and scanning electron microscope (SEM). The results show that with the increase in the deformation temperature and the decrease in the strain rate, the degree of dynamic recrystallization (DRX) gradually increased, and the morphology of the phase also changed through, for example, twist fracture. The continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms activated during the thermal deformation process can effectively refine the grains and weaken the texture in the alloy.
Highlights
The addition of Gd and Y can greatly improve the ductility and thermal stability of Mg alloys, which attenuates the shortcomings of the poor processing performance of Mg alloys at room temperature [3]
The large equiaxed grains and bone-like long-period stacking-ordered (LPSO) phase distributed at grain boundaries
With the increase in deformation temperature and the decrease in strain rate, the degree of recrystallization gradually increased, so the degree of recrystallization was largest at 450 ◦ C/0.001 s−1 in the experimental range
Summary
Magnesium (Mg) alloys have been widely studied and applied in recent years due to their light weight, low density and high specific strength [1]. The addition of rare-earth elements has greatly improved the strength and machinability of Mg alloys due to solidsolution strengthening and precipitation strengthening, which has helped the application of rare-earth Mg alloys to spread widely [2]. The addition of Gd and Y can greatly improve the ductility and thermal stability of Mg alloys, which attenuates the shortcomings of the poor processing performance of Mg alloys at room temperature [3]. By adding a small amount of Zn into Mg-Gd-Y alloys, the LPSO phase of Mg-RE-Zn alloys can be generated [4]. The. LPSO phase has the characteristics of high hardness, good thermal stability, good damping performance, high creep resistance and high elastic modulus [5]. The effect of this new structural strengthening phase on the mechanical properties of Mg alloys has attracted extensive attention from researchers, and has become a heavy focus of research into the strengthening and toughening of Mg alloys [6]
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