Heterogeneous nucleation of Mg2Si on CaSb2 nucleus in Al-Mg-Si alloys
Heterogeneous nucleation of Mg2Si on CaSb2 nucleus in Al-Mg-Si alloys
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Al-Mg-Si 合金中 Mg2Si 在 CaSb2 核上的异质形核
DOI：
10.1039/c5ce01271f
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发表时间：
2015-01-01
期刊：
影响因子：
3.1
通讯作者：
Jiang, Qi-Chuan
中科院分区：
文献类型：
--
作者：
Yu, Hong-Chen;Wang, Hui-Yuan;Jiang, Qi-Chuan
通过在Al-Mg-Si熔体中同时加入Ca和Sb制备了截断的八面体形貌和尺寸在8-15微米范围内的初生镁。首次发现，CaSb2在凝固过程中起到了初生镁硅的形核作用，显著改变了初生镁硅的形态，细化了初生镁硅的尺寸。这对改善Al-Mg-Si合金的力学性能是有益的。通过对Al-Mg-Si合金中提取的晶体的三维形貌的观察，确定了截断八面体初生镁硅晶体的骨架生长过程。Ca和Sb的含量对初生镁合金的形貌有重要影响，当含量从0增加到0.2，再增加到0.5wt%时，初生镁硅的形貌可以从粗大的枝晶转变为缺陷的截断八面体，最终转变为完全截断的八面体和平截的八面体共存。本研究提供了一种一步法、低成本地改变初生镁的形态和尺寸的方法，这对制备新型高强度、高韧性的轻质合金具有重要意义。
Primary Mg2Si with a truncated octahedral morphology and size over a range of 8-15 mu m were prepared by simultaneously adding Ca and Sb into the Al-Mg-Si melt. It is revealed for the first time that CaSb2 can act as the nucleus of primary Mg2Si during solidification, which changes the morphology and refines the size of primary Mg2Si significantly. It is useful for improving the mechanical properties of the Al-Mg-Si alloy. The skeleton-type growth processes of truncated octahedral primary Mg2Si crystals were identified by observation of the three-dimensional (3-D) morphologies of the crystals extracted from the Al-Mg-Si alloy. The content of Ca and Sb plays an important role in determining the morphologies of primary Mg2Si, which can be transformed from coarse dendrites to defective truncated octahedra and finally to the coexistence of perfect truncated octahedra and flat truncated octahedra with increasing the content from 0 to 0.2 and then to 0.5 wt%. Our study provided a one-step less-cost method to change the morphologies and sizes of primary Mg2Si, which is important to tailor new light-weight alloys with high strength and toughness.