Abstract:The effects of initial textures on the microstructures and mechanical properties of rolled Mg-4.7Gd- 3.4Y-1.2Zn-0.5Zr (wt.%) plates were studied by optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), transmission electron microscope (TEM) and tensile test. In the plate with an initial texture of á0001？//RD (rolling direction), relatively coarse grains and bimodal basal texture are developed. However, in the plate with an initial texture of á0001？//TD (transverse direction), finer grain size and strong á0001？//ND basal textures are obtained due to the higher degree of dynamic recrystallization during rolling. Additionally, the irregular-shaped long-period stacking ordered (LPSO) phases are elongated along RD in both plates, which results in anisotropic load-bearing strengthening behavior, and further leads to a certain degree of yield anisotropy. The analysis of the strengthening mechanism shows that grain boundary strengthening is the most effective strengthening method in the plates. Because of the finer grain size and the strengthening caused by the elongated irregular-shaped LPSO phases, the rolled plate with an initial á0001？//TD texture achieves the highest yield strength along RD.

Key words: Mg-Gd-Y-Zn-Zr alloy; texture; LPSO phase; mechanical properties; strengthening mechanism