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在氩气保护气氛下熔炼,得到Mg-5Li-xSn(x=0.15,0.25和0.65,质量分数)系列合金。通过光学显微镜、扫描电镜、X射线衍射仪和能谱仪分析合金的显微组织。结果表明,Mg-5Li合金中添加的Sn元素可以起到明显的晶粒细化作用,当Sn含量从0.15%增加到0.65%时,铸态合金的平均晶粒尺寸从556μm细化到345μm,相应的挤压态合金的晶粒从33μm减小到23μm。近似网状的第二相Mg2Sn分布在铸态合金的晶界上,挤压之后,颗粒状的Mg2Sn主要分布在晶粒内部。这些金属间化合物在挤压动态再结晶中可以作为有效的形核质点,从而起到细化晶粒的作用。
Smelting under an argon gas atmosphere to obtain a series of Mg-5Li-xSn (x = 0.15, 0.25 and 0.65, mass fraction) alloys. The microstructure of the alloy was analyzed by light microscopy, scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The results show that the addition of Sn element in Mg-5Li alloy can significantly improve the grain refinement. When the Sn content increases from 0.15% to 0.65%, the average grain size of as-cast alloy is refined from 556μm to 345μm, The grain size of the corresponding extruded alloy decreased from 33μm to 23μm. The approximately meshed second phase, Mg2Sn, is distributed on the grain boundaries of the as-cast alloy. After extrusion, the particulate Mg2Sn is mainly distributed inside the grains. These intermetallic compounds in the extrusion dynamic recrystallization can be used as an effective nucleation particle, which play the role of grain refinement.