Ageing behavior of Mg-9Li-6Al-xY(x = 0, 0.5, 2) alloys

The alloys of Mg-9Li-6Al-xY(0, 0.5, 2) were aged at 50 °C and 150 °C, respectively. The microstructure and hardness evolutions of the alloys during the ageing period were investigated. Results show that the morphology of MgLi2Al phase gradually varies from cross-rod to particle during the ageing period. When the ageing temperature is 50 °C, there exists no precipitation of AlLi phase in alfa(Mg). The precipitation of AlLi phase in alfa(Mg) happens when the ageing temperature is 150 °C. The addition of Y can restrain the precipitation of AlLi phase. The hardness of the alloys decreases with the ageing time, and the decreasing rate of the alloy with Y addition is somewhat lower than that of the alloy without Y addition.