Microstructure, texture, and mechanical properties of as-extruded Mg-xLi-3Al-2Zn-0.2Zr alloys (x = 5, 7, 8, 9, 11 wt%)

The microstructure, texture, and mechanical properties of as-extruded Mg-xLi-3Al-2Zn-0.2Zr alloys (x = 5, 7, 8, 9, 11 wt%) were investigated. After hot extrusion, the filamentous AlLi phase in α-Mg is crushed into tiny particles, while the morphology of round-like AlLi phase in β-Li remains unchanged. The threadlike MgLi2Al phase precipitated during hot extrusion only distributes along the grain boundaries of β-Li phase. The grains of as-extruded alloys are refined markedly due to dynamic recrystallization (DRX), and α-Mg phase undergoes discontinuous DRX while β-Li phase undergoes continuous DRX. The {0001} basal, {101¯0} and {112¯0} prismatic fiber textures formed in α-Mg phase suggest the activation of both basal and prismatic slip, and the intensity of prismatic texture is higher than that of basal texture. In β-Li phase, as the extrusion temperature increases and the Li content decreases, the intensities of α fiber and {110}110 textures decrease while those of γ fiber and {110}//ED textures increase. Compared with as-homogenized alloys, the mechanical properties of as-extruded alloys are significantly improved owing to grain refinement strengthening, texture hardening, strain hardening, and second phase strengthening.