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分别采用金相,扫描电镜,X射线衍射,电子探针和波谱分析的手段,对一种加入不同铈含量(0,0.1,0.3,and 0.5,质量分数,%的新型Al-Cu-Li合金的铸态微观结构进行了研究。结果表明:随着含铈量的增加,晶粒得到很大程度的细化;在含铈量不超过0.3%的所有试验合金中,均观察到了一种MgAg富集的Al_7Cu_4Li中间相;当含铈量达到0.5%,一种新型的灰色CuSi(Ag Mg)相出现;然而粗大的杆状Al_2CuLi相在含铈量达到0.3%就已经完全消失。分析表明:铈添加导致本试验合金中的中间相的析出序列和凝固行为发生了改变;同时分析发现在合金凝固过程中产生的一种先析Al_8Cu_4Ce相,不但能够促进晶粒形核,同时能够阻止晶粒进一步长大,最终导致含铈的铸态合金晶粒得到细化。
A new kind of Al-Cu-Li alloy with different cerium content (0,0.1,0.3, and 0.5, mass fraction,%) was prepared by means of metallographic examination, scanning electron microscopy, X-ray diffraction, electron probe and spectral analysis. The results show that the grain size is greatly refined with the increase of the content of cerium. In all the tested alloys containing no more than 0.3% cerium, one kind of MgAg Enriched Al_7Cu_4Li mesophase.When the amount of cerium reached 0.5%, a new type of gray CuSi (Ag Mg) phase appeared.However, the coarse rod-like Al_2CuLi phase completely disappeared when the content of cerium reached 0.3% .Analysis showed that: The addition of cerium led to the change of the precipitation sequence and the solidification behavior of the mesophase in the test alloy. It was also found that the first phase Al_8Cu_4Ce phase produced during the solidification of the alloy not only promoted grain nucleation, but also prevented grain growth Further growth, eventually resulting in cerium-containing as-cast alloy grains are refined.