Precipitation process and effect on mechanical properties of Mg–9Gd–3Y–0.6Zn–0.5Zr alloy

Precipitation process and its effect on the Vickers hardness, room temperature tensile properties of Mg–9Gd–3Y–0.6Zn–0.5Zr (GWZ930) alloy were investigated in combination with differential scanning calorimetric (DSC), transmission electron microscopy (TEM), Vickers hardness and room temperature tensile test. A four-stage precipitation sequence of supersaturated Mg solid solution, Mg(SSSS) → β″ (144 °C) → β′ (240 °C) → β1 (276 °C) → β (stable), was analyzed. A satisfied combination of high rupture tensile strength and ductility was obtained when the alloy was aged at 200 °C for 63 h post extrusion. Moreover, the effective strengthening mechanisms were explicitly considered and the model prediction strength of GWZ930 alloy was proposed. It is concluded that precipitate strengthening due to the sub-micron metastable phases of β″ and β′ was the largest contributor to the room temperature tensile strength of the alloy GWZ930.