Microstructure and tensile properties of as-extruded Mg-Li-Zn-Gd alloys reinforced with icosahedral quasicrystal phase

Mg-Li-Zn-Gd alloys reinforced with icosahedral quasicrystal phase (I-phase) were prepared by casting and deformed by hot extrusion. The microstructure and tensile properties of as-extruded Mg-Li-Zn-Gd alloys were investigated. It is found that I-phase formed in as-cast Mg-Li-Zn-Gd alloys and was broken into small particles during extrusion. After hot extrusion, both α-Mg and β-Li phases were elongated along the extrusion direction. Dynamic recrystallization occurred in as-extruded Mg-Li-Zn-Gd alloys. Compared with Mg-9Li (L9) alloy, the improvement in mechanical properties especially the tensile strength of the as-extruded Mg-Li-Zn-Gd alloys was mainly ascribed to the formation of I-phase and their volume fraction. Moreover, the finely recrystallized grain structure can also attribute to the strength enhancement of the alloy.