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

Abstract

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 α-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.