Enhanced Mechanical Properties of Extruded Mg–9mass%Al–1mass%Zn–2mass%Ca Alloy

In order to investigate the relationships between microstructure and mechanical properties of extruded Mg–9mass%Al–1mass%Zn–2mass%Ca (AZX912) alloy, the AZX912 alloy ingots with and without solution treatment (ST) were extruded at a low temperature of 523 K, and some extrusions were subsequently annealed at 473–573 K. The as-extruded bar exhibited dynamically recrystallized fine grains, and the amount of fine Mg17Al12 precipitates in grains. Grain coarsening occurred with an increased grain size from ~2 to ~8 μm after annealing. Solution treatment seems to affect grain coarsening during extrusion. All extruded bars exhibited basal texture, and the extruded bar annealed at 573 K exhibited slightly lower texture intensity than the others. The extruded bar exhibited high mechanical strength of 377 MPa and medium elongation of 6.6%, when solution treatment before extrusion and final annealing were not applied. The high mechanical strength was likely attributed to the small grain size, large work hardening and a great amount of fine Mg17Al12 precipitates in the extrusions.