Combined effects of LPSO orientation and α-Mg texture on tensile anisotropy of an extruded Mg-Gd-Y-Zn-Zr alloy

The combined effects of LPSO orientation and alpha-Mg texture on tensile anisotropy were investigated for an extruded Mg-Gd-Y-Zn-Zr alloy with a typical bimodal microstructure, a strong basal fiber texture, and directionally arranged LPSO phases. Results indicate that the extrusion direction (ED) exhibits the optimal mechanical properties in all aspects. The 45 degrees direction presents a high elongation, while the transverse direction (TD) was endowed with the inferior strength and elongation simultaneously. The LPSO orientation contributes to the strength anisotropy via different load-bearing strengthening effect along different tensile axis. Meanwhile, the deformed alpha-Mg grains, which exhibit stronger basal fiber texture and more prismatic slip when loaded along ED, account for the rest contribution to strength anisotropy via the stronger grain boundary strengthening effect. However, LPSO orientation rather than alpha-Mg texture accounts for the ductility anisotropy, since microcracks tend to initiate at the alpha-Mg/LPSO interface and LPSO orientation modifies the fracture mode via affecting the initiation and propagation of microcracks.