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

Highlights: → Texture evolution in three magnesium extrusions are investigated and corresponded with mechanical properties. → Nd introduces random texture in Mg extrusion and provides good yield symmetry as well as ductility. → Zn addition to Mg-Nd binary alloy weakens the rare earth texture. → Aging makes grains rotate their c-axes closer to ED and improve yield symmetry further. → Modified texture is responsible for the good yield symmetry and ductility. - Abstract: 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 deg. 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.