Barrirero J, Pauly C, Engstler M, Ghanbaja J, Ghafoor N, Li J, Schumacher P, Odén M, Mücklich F
Functional Materials, Department of Materials Science, Saarland University, D-66123, Saarbrücken, Germany.
Nanostructured Materials, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183, Linköping, Sweden.
Sci Rep. 2019 Apr 2;9(1):5506. doi: 10.1038/s41598-019-41919-2.
Al-alloys with Si as the main alloying element constitute the vast majority of Al castings used commercially today. The eutectic Si microstructure in these alloys can be modified from plate-like to coral-like by the addition of a small amount of a third element to improve ductility and toughness. In this investigation the effects of Eu and Yb are studied and their influence on the microstructure is compared to further understand this modification. The two elements impact the alloy differently, where Eu modifies Si into a coral-like structure while Yb does not. Atom probe tomography shows that Eu is present within the Si phase in the form of ternary compound AlSiEu clusters, while Yb is absent in the Si phase. This indicates that the presence of ternary compound clusters within Si is a necessary condition for the formation of a coral-like structure. A crystallographic orientation relationship between Si and the AlSiEu phase was found, where the following plane normals are parallel: 011//0001, 111//6[Formula: see text]10 and 011//6[Formula: see text]10. No crystallographic relationship was found between Si and AlSiYb. The heterogeneous formation of coherent AlSiEu clusters inside the Si-phase is suggested to trigger the modification of the microstructure.
以硅作为主要合金元素的铝合金构成了当今商业应用中绝大多数的铝铸件。通过添加少量第三种元素，这些合金中的共晶硅微观结构可以从片状转变为珊瑚状，以提高延展性和韧性。在本研究中，对铕和镱的影响进行了研究，并将它们对微观结构的影响进行比较，以进一步了解这种微观结构的改变。这两种元素对合金的影响不同，其中铕将硅转变为珊瑚状结构，而镱则不会。原子探针断层扫描显示，铕以三元化合物AlSiEu团簇的形式存在于硅相中，而硅相中不存在镱。这表明硅相中三元化合物团簇的存在是形成珊瑚状结构的必要条件。发现了硅与AlSiEu相之间的晶体取向关系，其中以下晶面法线平行：011//0001、111//6[公式：见原文]10和011//6[公式：见原文]10。未发现硅与AlSiYb之间的晶体关系。硅相内部相干AlSiEu团簇的非均匀形成被认为触发了微观结构的改变。
