Abstract:Mg−5Li−xSn (x=0.15, 0.25 and 0.65, mass fraction) alloys were prepared. The microstructures of these alloys were investigated through optical microscope (OM), scanning electron microscope (SEM), X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS). The results indicate that Sn additions produce a strong grain refinement effect on Mg−5Li alloy. The mean grain size of as-cast Mg−Li alloys with Sn is reduced remarkably from 556 μm to 345 μm, and that of the as-extruded alloys is reduced from 33 μm to 23 μm when the Sn content increases from 0.15% to 0.65%. The near net-like Mg₂Sn phase in the as-cast alloys is verified at the grain boundaries. After extrusion, the granular Mg₂Sn phase mainly exists inside the grains and thus can act as nucleation sites of α-Mg grains during the dynamic recrystallization and make the microstructure finer.

Key words: Mg−Li alloys; grain refinement; intermetallic compound; Sn