Simultaneous grain refinement and eutectic Mg2Si modification in hypoeutectic Al-11Mg2Si alloys by Sc addition
Simultaneous grain refinement and eutectic Mg2Si modification in hypoeutectic Al-11Mg2Si alloys by Sc addition
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DOI：
10.1016/j.jallcom.2019.03.326
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发表时间：
2019-06
影响因子：
6.2
通讯作者：
X. Wu;Ke-yan Wang;Fu-fa Wu;R. Zhao;Minghua Chen;Jun Xiang;Sheng-Na Ma;Yue Zhang
中科院分区：
文献类型：
--
作者：
X. Wu;Ke-yan Wang;Fu-fa Wu;R. Zhao;Minghua Chen;Jun Xiang;Sheng-Na Ma;Yue Zhang
研究了Sc对亚共晶Al-11 Mg 2Si合金显微组织、力学性能和断裂行为的影响。结果表明，微量Sc对亚共晶Al-11 Mg 2Si合金中初生α-Al相和共晶Mg 2Si相具有明显的细化和变质作用。初生α-Al相由粗大的枝晶转变为细小的球状晶体。此外，共晶Mg 2Si相的形态从粗糙的片状形状转变为细小的短纤维状。力学性能，特别是极限拉伸强度和延展性，因此可以显着提高。结果表明，初生α-Al相的细化和Mg 2Si相的变质作用是由于Al 3Sc异质形核的形成、Sc的偏聚以及在长大的Mg 2Si相前面的成分过冷所致。这一发现意味着，在亚共晶Al-Mg_2Si合金中，通过适当的微量或微量Sc合金化可以同时实现初生α-Al晶粒细化和共晶Mg_2Si变质。
The effect of Sc addition on the microstructure, mechanical properties and fracture behavior of hypoeutectic Al-11Mg2Si alloys were investigated. The results indicate that the trace addition of Sc has significant refine and modification effect on the primary α-Al and eutectic Mg2Si phases in the hypoeutectic Al-11Mg2Si alloy. The morphology of the primary α-Al phase is changed from coarse dendrites to fine spheroidal crystals. Moreover, the morphology of the eutectic Mg2Si phase is changed from a coarse flake-like shape to fine and short fibrous. The mechanical properties, especially the ultimate tensile strength and ductility, can therefore be significantly improved. It is suggested that the simultaneous grain refine of primary α-Al phase and modification of Mg2Si phase are attributed to the formation of Al3Sc heterogeneous nucleus, the Sc segregation and the corresponding composition supercooling in front of the growing Mg2Si phase. This finding implies that simultaneous primary grain α-Al refinement and eutectic Mg2Si modification in hypoeutectic Al-Mg2Si alloys could be achieved by suitable trace or minor Sc alloying.