Effect of Gd content on high temperature mechanical properties of Mg-Gd-Y-Zr alloy

In this study, the compositional dependence of the age hardening response and high temperature tensile properties of the Mg-xGd-3Y-0.5Zr (x=3, 6, 10, and 12 wt%) alloys are investigated. The amount of cuboid-shaped phases and β′ precipitates increased significantly with increasing the Gd content. The Mg-10Gd-3Y-0.5Zr alloy exhibited the maximum ultimate tensile strength at room temperature, while at higher temperatures the Mg-12Gd-3Y-0.5Zr alloy exhibited the maximum yield strength and ultimate tensile strength. The yield strength and ultimate tensile strength of the Mg-12Gd-3Y-0.5Zr alloy increased with the test temperature and showed its maximum at 150 °C, and then decreased as the temperature increased further. The Mg-12Gd-3Y-0.5Zr alloy maintained a high ultimate tensile strength of more than 300 MPa up to 250 °C. The superior high temperature tensile strength of the tested alloy is mainly associated with solution strengthening and precipitation hardening of the cuboid-shaped phases and β′ precipitates in Mg matrix. Especially, β′ precipitates can hinder the dislocation movement at high temperature.