Ce含量对Mg-Li-Al-Zn合金显微组织和拉伸性能的影响

摘要

Mg-5Li-3Al-2Zn-xCe (x=0-2.5; mass fraction,％) alloys were prepared by casting,and heat treatments of homogenization at 300 ℃ and solid solution at 370 ℃ were carried out.The microstructure and tensile properties of as-cast alloys and their evolutions after solid solution were investigated.The results show that with the increase of Ce content,Al2Ce/Al3Ce precipitates are formed and the alloys mainly consist of α-Mg,Al2Ce,Al2Ce and AlLi phases,and thc amount of AlLi and Al-Ce intermetallics decreases after solid solution.The content and morphology of the second phases have important effccts on the mechanical properties of the alloys; the alloy with 1.0％Ce content exhibits excellent tensile strength.The tensile strength and elongation of Mg-5Li-3Al-2Zn-0.5Ce alloy is remarkably improved by the solution strengthening effect because of the addition of Ce.%制备了Mg-5Li-3AI-2Zn-xCe(X=0-2.5:质量分数,％)铸态合金,并将所得合金分别于300℃和370℃进行均匀化和固溶处理;研究固溶处理后合金显微组织和拉伸性能的变化.结果表明,合金中加入Ce后出现Al2Ce/Al3Ce析出相,此时合金主要由α-Mg、Al2Ce、Al3Ce和AlLi相组成；固溶处理后合金中AlLi和Al-Ce析出相数量减少.析出相的数量与形态对合金的力学性能十分重要,含有1.0％Ce的合金获得了优良的拉伸性能.固溶处理后Mg-5Li-3Al-2Zn-0.5Ce合金的强度和伸长率都得到了大幅度的提高,这是因为合金在固溶处理后由于基体中的溶质原子增加而获得良好的固溶强化作用.