Thermal compression, processing maps and microstructural evolution of as-cast Mg-Gd-Y-Zn-Zr alloy with long period stacking ordered phase

Abstract

Thermal deformation of Mg-7.5Gd-2.5Y-1.5Zn-0.5Zr (wt%) as-cast alloy containing LPSO phase was been studied in a temperature range from 623 K to 723 K and a strain rate range from 0.001 to 1 s −1 . The microstructural evolution at the various strain rates was also analyzed. The results show that the flow stress decreases significantly with the increase of the deformation temperature. But the peak flow stresses of the alloy increase significantly at high deformation temperature, due to existing both the plentiful lamellar LPSO phase and the fine dynamic DRXed grains. Under the high strain rate conditions, the LPSO phase distorted and formed kink bands. The deformational activation energy (Q) of the alloy is about 234.6 kJ·mol −1 . This high Q value mainly owe to profuse lamellar LPSO phase hindering the movement of atoms. With the observation of established processing map of the alloy, some good thermal workabilities are observed in following zones: 723 K, 0.001<ε<1 s −1 ; and the zone with middle temperature and moderate strain rate condition, 673 K, 0.01<ε<0.1 s −1 . The thermal deformation instability zones are mainly located in the region with high strain rate and lower temperature.

Effect of Deformation Parameters on Recrystallization Behavior and Long-Period Stacking-Ordered Phase of Mg-9Gd-4Y-2Zn-0.5Zr Alloy

“…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 ].…”

Effect of homogenization on microstructure evolution and mechanical properties of aged Mg-Nd-Sm-Zn-Zr alloy

“…Magnesium (Mg) -rare earth (RE) alloys have been greatly developed in the past decades due to their low density, good corrosion resistance and potential for energy saving [1][2][3][4][5]. Hence, the Mg-RE alloys are widely applied in aerospace, electronic communication and automobile applications [6].…”