Texture role in the mechanical property improvement contributed by grain refinement for Mg-2.6Nd-0.55Zn-0.5Zr alloy subjected to extrusion process

This work successfully fabricated the fine-grained Mg-2.6Nd-0.55Zn-0.5Zr (wt%) alloy plates with the average grain sizes of 2.39-3.49 mu m via the extrusion process. The microstructure evolution during extrusion process and the associated mechanical properties were investigated. Results showed that dynamic recrystallization (DRX) significantly refined the grain size and improved the microstructure homogeneity. Extrusion fragmentation effect on the coarse Mg12Nd particles contributed to the development of fine-grained uniform microstructure, especially at the lower extrusion temperature. Additionally, extrusion process turned the fiber basal texture into the double peak basal texture owing to the sequential deformation mode activation from basal slip and tension twinning to pyramidal c+a c+a slip and weakened the effect of PSN on texture modification, leading the basal plane distribution along the extrusion direction to be strengthened. Finegrained strengthening significantly improved the mechanical properties, but such strengthening capability was severely dependent on the texture. During tension deformation, the weak basal texture easily activated the basal slip whereas the strong basal texture needed to activate the prismatic slip. Hall-Petch analysis indicated that the higher yield stress in the strong basal texture was ascribed to the remarkable deformation mode strengthening (activation of prismatic slip) and the geometrical strengthening (higher Taylor factor). The weak basal texture was beneficial to improve the uniform elongation owing to the higher strain hardening ability, which was more obvious when the tension twinning was activated.