Effect of heat treatment on microstructures and mechanical properties of sand-cast Mg-10Gd-3Y-0.5Zr magnesium alloy

The microstructure, mechanical properties and fracture behavior of sand-cast Mg-10Gd-3Y-0.5Zr alloy (mass fraction, %) under T6 condition (air cooling after solid solution and then aging heat treatment) were investigated. The optimum T6 heat treatments for sand-cast Mg-10Gd-3Y-0.5Zr alloy are (525 °C, 12 h + 225 °C, 14 h) and (525 °C, 12 h + 250 °C, 12 h) according to age hardening curve and mechanical properties, respectively. The ultimate tensile strength, yield strength and elongation of the Mg-10Gd-3Y-0.5Zr alloy treated by the two optimum T6 processes are 339.9 MPa, 251.6 MPa, 1.5% and 359.6 MPa, 247.3 MPa, 2.7%, respectively. The tensile fracture mode of peak-aged Mg-10Gd-3Y-0.5Zr alloy is transgranular quasi-cleavage fracture.