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采用光学显微镜、带能谱仪的扫描电镜、X射线衍射仪以及电子万能试验机,研究了镧镨铈混合稀土对Mg-Li-Al合金显微组织和力学性能的影响。结果表明:加入镧镨铈混合稀土能显著细化合金组织,起到细晶强化和提高塑性的作用;同时Al和La生成稀土化合物Al11La3,大量富集在晶界上,能阻止晶界滑移和基体变形,有强化晶界的作用。随着稀土加入量增大,Mg与La生成Mg3La,消耗了部分Mg,使得强度略为降低,塑性提高,相对于未加入混合稀土的Mg-Li-Al合金,其抗拉强度和伸长率分别提高了27.3%和1248.1%;当混合稀土含量为3%时合金强度最高,含量为4%时塑性最好。
The effects of lanthanum-praseodymium-cerium mixed rare earth on the microstructure and mechanical properties of Mg-Li-Al alloy were investigated by optical microscope, scanning electron microscope with energy dispersive spectrometer, X-ray diffraction and electronic universal testing machine. The results show that the addition of lanthanum-praseodymium-cerium mixed rare earth can remarkably refine the alloy microstructure and play the role of fine grain strengthening and plasticity enhancement. At the same time, Al and La generate the rare earth compound Al11La3 which is enriched in the grain boundary and can prevent the grain boundary slip And the substrate deformation, the role of strengthening grain boundaries. With the increase of RE content, Mg and La generate Mg3La and consume some Mg, resulting in a slight decrease in strength and plasticity. The tensile strength and elongation of the Mg-Li-Al alloy are respectively increased compared with those of the Mg-Li-Al alloy without addition of rare earth 27.3% and 1248.1% respectively. When the content of rare earth is 3%, the strength of the alloy is the highest, and the plasticity is best when the content is 4%.