The columnar-to-equiaxed transition in Pb–Sn alloys affected by electromagnetically driven convection
The columnar-to-equiaxed transition in Pb–Sn alloys affected by electromagnetically driven convection
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DOI：
10.1016/j.msea.2005.03.108
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发表时间：
2005-08
期刊：
影响因子：
6.4
通讯作者：
B. Willers;S. Eckert;U. Michel;I. Haase;G. Zouhar
中科院分区：
文献类型：
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作者：
B. Willers;S. Eckert;U. Michel;I. Haase;G. Zouhar
本文报道了旋转磁场对铅锡合金定向凝固影响的实验研究。由RMF产生的熔体中的整体流动的幅度随着磁泰勒数Ta=σω B2 R4/2ρν2而变化。强制对流引起温度和浓度场的明显变化，例如凝固前沿之前的温度梯度减小。在没有电磁搅拌的情况下，合金仅以平行于热流方向排列的枝晶的形式固化。相比之下，如果凝固锭暴露于RMF，则观察到从柱状到等轴生长（CET）的转变。通过增加Ta值，CET的位置朝向铸件的底部移动。发现CET发生在约0.4K/s的冷却速率和在0.6和1.0K/mm之间的范围内的温度梯度。
An experimental study with respect to the influence of a rotating magnetic field (RMF) on the unidirectional solidification of Pb–Sn alloys is reported. The magnitude of the bulk flow in the melt generated by the RMF varies with the magnetic Taylor number Ta=σωB2R4/2ρν2. The forced convection causes distinct modifications of the temperature and concentration field such as a reduction of the temperature gradient ahead of the solidification front. Without electromagnetic stirring, the alloy solidifies solely in form of dendrites aligned parallel to the heat flow direction. In contrast, a transition from columnar-to-equiaxed growth (CET) is observed if the solidifying ingot is exposed to an RMF. The position of the CET is shifted towards the bottom of the casting by increasing the Ta number. The CET was found to occur for a cooling rate of about 0.4K/s and temperature gradients in the range between 0.6 and 1.0K/mm.