Effect of aging precipitation on mechanical anisotropy of an extruded Mg–Y–Nd alloy

Wrought Mg alloys especially precipitation-hardenable rare-earth alloys have promising potential for structural applications. However, wrought Mg alloys usually possess deformation texture leading to strong mechanical anisotropy. This is an obstacle to the application of wrought Mg alloys. Therefore, exploiting the methods to eliminate or reduce the mechanical anisotropy is one of the hot research topics related to Mg alloys. In this study, the effect of aging precipitation on the mechanical anisotropy of an extruded Mg–Y–Nd alloy was studied. The results showed that the extruded alloy presented a weak basal fiber texture and after peak-aging at 210 °C for 59 h, β′ precipitates were primarily formed. The extruded alloy exhibited obvious anisotropies of yield strength and strain hardening. But after precipitation of β′ precipitates the yield strength anisotropy of the peak-aged alloy was effectively reduced. The difference of yield strength between the specimens compressed along extrusion direction (ED) and perpendicular to ED was reduced from ∼34 MPa to ∼7 MPa. Additionally, the strain hardening rate anisotropy was also reduced by aging precipitation. Extension twinning was not largely observed in the deformed samples indicating it is not the main reason contributed to the mechanical anisotropy. This study suggests that the mechanical anisotropy of wrought precipitation-hardenable Mg alloys can be effectively reduced by aging treatments.

► Aging precipitation largely reduced yield strength anisotropy. ► Strain hardening rate anisotropy was also reduced by aging precipitation. ► {10–12} twinning was not the main reason for mechanical anisotropy.