Texture and mechanical behavior evolution of age-hardenable Mg–Nd–Zn extrusions during aging treatment

Three magnesium alloys containing different Nd and Zn were extruded and heat treated. The addition of Nd gives rise to the RE texture (c-axis oriented at an angle lower than 90° to the extrusion axis) in extruded Mg rods, reducing yield strength, improving tension–compression asymmetry and enhancing ductility. The Zn addition, on the other hand, weakens the RE texture by rotating the c-axes of the grains away from the extrusion axis, and also leads to the formation of a significant amount of Mg–Nd–Zn intermetallics at grain boundaries and triple points for concentrations above 0.2 wt.%. Heat treatment after extrusion causes significant age hardening as well as makes the grains reorient and further improvement on yield symmetry together. When the effect of age-hardening is included, the Mg–3.0Nd–0.2Zn–Zr (wt.%) extrusion is found to provide the best combination of strength, ductility and tension–compression asymmetry.