Deformation mechanism of fine grained Mg-7Gd-5Y-1.2Nd-0.5Zr alloy under high temperature and high strain rates

Fine grained Mg-7Gd-5Y-1.2Nd-0.5Zr alloy was investigated by dynamic compression tests using a Split Hopkinson Pressure Bar under the strain rates in the range 1000-2000 s(-1) and the temperature range 293-573 K along the normal direction. The microstructure was measured by optical microscopy, electron back-scattering diffraction, transmission electron microscopy and X-ray diffractometry. The results showed that Mg-7Gd-5Y-1.2Nd-0.5Zr alloy had the positive strain rate strengthening effect and thermal softening effect at high temperature. The solid solution of Gd and Y atoms in Mg-7Gd-5Y-1.2Nd-0.5Zr alloy reduced the asymmetry of alpha-Mg crystals and changed the critical shear stress of various deformation mechanisms. The main deformation mechanisms were prismatic slip and pyramidal < a > slip, {102} tension twinning, and dynamic recrystallization caused by local deformation such as particle-stimulated nucleation. (C) 2020 Published by Elsevier B.V. on behalf of Chongqing University.