The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys
The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys
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DOI：
10.1016/0921-5093(96)10392-0
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发表时间：
1996-10-15
期刊：
影响因子：
6.4
通讯作者：
McCartney, DG
中科院分区：
文献类型：
--
作者：
Griffiths, WD;McCartney, DG
一系列的Al-Si合金挖土在矩形腔中垂直向下固化，并用可控的电磁搅拌器获得的散装液体流量变化。对其宏观结构的检查表明，通过增加散装液体速度和增加硅含量来促进柱状等轴承的过渡。凝固过程中的温度测量表明，电磁搅拌导致散装液体超热的快速去除，因此相对冷的液体对固化锋的影响。流体流量模型表明，获得了高达0.25 m a S（-1）的大量液体速度。固化前端的碎片是用高速流促进柱状等轴线过渡的最可能的机制。然而，在低速流中，例如自然对流或电磁搅拌的有限应用，柱状等轴线的过渡可能受到异质成核效应的显着影响。证据来自比较使用具有不同纯度的铝和硅制备的合金的行为。
A series of Al-Si alloy ingots were directionally solidified vertically downwards in a rectangular cavity with varying conditions of bulk liquid flow obtained with a controllable electromagnetic stirrer. Examination of their macrostructures showed that the columnar-equiaxed transition was promoted both by increasing bulk liquid velocity and increasing silicon content. Temperature measurements during solidification showed that the electromagnetic stirring resulted in the rapid removal of bulk liquid superheat and therefore the impact of a relatively cold liquid on the solidification front. Fluid flow modelling showed that bulk liquid velocities of up to 0.25 m a s(-1) were obtained. Fragmentation of the solidification front was the most probable mechanism for the promotion of the columnar-equiaxed transition with high velocity flows. However, with low velocity flows, such as were obtained with natural convection or a limited application of electromagnetic stirring, the columnar-equiaxed transition was probably significantly influenced by heterogeneous nucleation effects. Evidence for this came From comparing the behaviour of alloys prepared using aluminium and silicon of different levels of purity.