通过XRD,DSC,SEM,EDS等现代分析方法,研究了稀土元素Ce在不同凝固冷却速率下对Al ZwMg-Cu合金显微组织、凝固温度的影响,分析讨论了Ce对合金晶粒细化和熔体净化作用的原理.结果表明,合金的主要析出相为α-Al和MgZn2型共晶相,MgZn2固溶了Al,Cu,Mg等元素并形成了Mg(Zn,Cu,Al)2相,在晶界上溶质元素浓度较高,与α-Al基体共晶形成层片状共晶组织.添加Ce能使合金枝晶间距减小,并减小共晶层片间距和细化共晶组织,显著细化晶粒,并抑制铝合金中的杂质相Al7 Cu2 Fe的出现.Ce还将合金α-Al基体和共晶相的析出温度分别降低了6.4℃和5.6℃.%Through using XRD,DSC,SEM,EDS and other modern analysis methods,the effects of rare earth element Ce on microstructure and solidification temperature of Al-Zn-Mg-Cu under different cooling rates were studied,the principle of Ce on grain refining and melt cleaning of alloys was analyzed and discussed.The results show that MgZn2 phase and α-Al matrix are the main precipitations,Al,Cu,Mg and other elements dissolve in MgZn2 phase,a new phase Mg(Zn,Cu,Al)2 is formed,solute elements in the grain boundary have higher concentration,eutectic reaction takes place between MgZn2 and α-Al,lamellar eutectic structure is generated.The addition of Ce decreases the dendritic arm spacing,reduces the layer spacing between eutectic phases and refines the eutectic structure and the grain significantly,and inhibits the appearance of the impurity phase Al7Cu2Fe in aluminum alloys.The addition of Ce also reduces the precipitation temperature of α-Al matrix and eutectic phase by 6.4℃ and 5.6℃ respectively.
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