Effect of a magnetic field on macro segregation of the primary silicon phase in hypereutectic Al-Si alloy during directional solidification
Effect of a magnetic field on macro segregation of the primary silicon phase in hypereutectic Al-Si alloy during directional solidification
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DOI：
10.1016/j.jallcom.2017.06.084
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发表时间：
2017-10-25
影响因子：
6.2
通讯作者：
Li, Xi
中科院分区：
文献类型：
--
作者：
Hu, Shaodong;Dai, Yanchao;Li, Xi
研究了静磁场对定向凝固过共晶铝硅合金初生硅相纵向宏观偏析的影响。实验和数值模拟结果表明，Al-21 wt% Si合金在磁场作用下的熔体流动是导致初生硅相宏观偏析的主要因素。强烈的熔体流动，即再循环回路和微观流动，促使溶质Si向温度较低的糊状区和坩埚侧壁移动，初生硅更容易析出，从而形成Ushaped界面。在定向凝固过程中，析出的初生硅趋于消失，导致从u型界面向平面界面转变。磁场强度的增加加速了这一转变过程，加剧了宏观偏析。此外，体熔体中自由飘移的硅微粒被强制流动输送到糊状区，导致宏观偏析。本工作有助于理解定向凝固过程中磁场作用下强迫流动对合金凝固组织的巨大改变。(C) 2017年Elsevier B.V.出版
Effect of static magnetic field on longitudinal macro segregation of primary silicon phase has been investigated in directionally solidified hypereutectic Al-Si alloy. Experimental and numerical simulation results indicate that the melt flow of Al-21 wt% Si alloy under magnetic field is the dominant factor leading to macro segregation of primary silicon phase. The intense melt flow, i.e., recirculation loops and microscopic flow, promotes solute Si to the mushy zone and sidewall of the crucible where the temperature is low and the primary silicon is more likely to precipitate, resulting in the formation of the Ushaped interface. The precipitated primary silicon tends to disappear during directional solidification, which induces the transition from the U-shaped interface to the planar interface. The increase of magnetic field intensity accelerates this transition process and increases the macro segregation. Furthermore, the freely drifted fine silicon particles in the bulk melt are transported to mushy zone by the forced flow, which contributes to macro segregation. This work facilitates the understanding of forced flow greatly changing the solidification structures of alloys under the magnetic field during directional solidification. (C) 2017 Published by Elsevier B.V.