Evolution of Texture and Mechanical Anisotropy of Mg-13Gd-4Y-2Zn-0.5Zr Sheet Produced by Rotary Forward Extrusion

The evolution of texture and mechanical anisotropy of Mg-13Gd-4Y-2Zn-0.5Zr sheet produced by rotary forward extrusion (RFE) were investigated. The microstructures were observed by using optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscope. The result shows, compared with conventional forward extrusion (CFE), the mechanical anisotropy of RFE samples with accumulated strong shear strain is significantly weakened. The mechanical anisotropy is positively correlated with grain size difference, long period stacking ordered (LPSO) phase morphology difference, and dislocation configuration difference. The dynamic recrystallization (DRX) area fraction difference of RFE-M sample (5.3%) and RFE-S sample (4.8%) was much lower than that of CFE-M sample (22.7%) and CFE-S sample (7.9%), and the grain size difference of RFE-M and RFE-S samples was also lower than of CEF-M and CEF-S samples. This indicates the decrease of DRX area fraction difference during RFE process is contributed to the decrease of DRX area fraction difference. With the introduction of strong shear stress during RFE, the kinking and fragmentation of LPSO phases in each direction is more severe, and the morphological difference in each direction is decreased, so the mechanical anisotropy is significantly weakened.