Microstructure evolution and microhardness of Mg-13Gd-4Y–2Zn-0.5Zr alloy via pre-solution and multi-directional forging (MDF) process

Abstract The Mg-13Gd-4Y–2Zn-0.5Zr (wt.%) alloy containing high-content long-period stacking ordered (LPSO) phases is pre-solutioned prior to multi-directional forging (MDF) process. The microstructural evolution of the experimental alloy via MDF method after 4 passes is studied by the ways of optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and electron backscattered diffraction (EBSD), and the mechanical properties of the MDFed alloys after different passes is calibrated by vickers hardness. Unlike conventional MDF method, we perform pre-solution treatment for the MDFed alloys from 2 passes to 4 passes in order to make more precipitation phases be resolved to strengthen the Mg matrix and obtain the uniform microstructure. It is obvious to find that amount of plate-like Mg5RE phases are existing in the 4MDFed sample. And the occurrence of the plate-like Mg5RE phases is attributed to the activation of basal slip and prismatic slip under certain strain conditions in the deformation processing.