Fabrication of high strength α, α+β, β phase containing Mg-Li alloys with 0.2%Y by extruding and annealing process

The microstructural evolution and a precipitation strengthening behavior of Mg-xLi-3Al-2Zn-0.2Y (x=5, 8, 11) by extruding and annealing process were investigated. Results show that when annealing at 300 °C for 6 h and 12 h and 24 h, the MgAlLi2 phase decomposes and vanishes from the matrices, meanwhile, recrystallization behavior of α and β grains can be observed. After annealing at 250 °C, in the Mg-8Li-3Al-2Zn-0.2Y and Mg-11Li-3Al-2Zn-0.2Y, a great deal of intermetallic compounds (1.8-2.5 µm) extensively precipitate from β phase. In contrast, no evident precipitation behavior happens in the Mg-5Li-3Al-2Zn-0.2Y. The large number of dispersive precipitates in β phase significantly enhance the strength of the alloys.