Effect of pre-solution treatment on the texture and the mechanical properties of hot-extruded Mg-2.6Nd-0.55Zn-0.5Zr alloys

Abstract

This work realized the texture tailor of Mg-2.6Nd-0.55Zn-0.5Zr (wt.%) alloy sheets via the hot extrusion on the billets subjected to different solution times from 0 h to 16 h. The solution treatment of 530 °C could effectively dissolve the coarse Mg12Nd particles. But abundant small second phase particles again developed after hot extrusion owing to the solid solution decline of Nd in magnesium matrix and the strain induced precipitation. The occurrence of dynamic recrystallization during hot extrusion improved the microstructure homogeneity and refined the grain sizes to 4.2–5.7 μm. Additionally, the activations of basal slip, prismatic slip and pyramidal <c+a> slip together promoted the development of double peak basal texture in the hot-extruded sheets. However, this kind of texture was weakened by the particle-stimulated nucleation recrystallization and its weakening degree gradually decreased with the prolongation of solution time. This made the sheet with the long solution time more likely retain the strong deformation basal texture. Such strong basal texture increased the activation fraction of prismatic slip along the extrusion direction (ED), producing the higher yield stress and the lower uniform elongation. Influenced by this, the anisotropies in the yield stress and the uniform elongation between the ED and the transverse direction (TD) were obviously weakened. Besides, the activation of tension twinning greatly increased the uniform elongation and decreased the yield stress.