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本文研究了pb—Sn共晶合金定向凝固条件下电磁搅拌对层片组织的影响。结果发现,Pb—Sn合金共晶组织明显粗化,并且层片间距随着半径的增加而增加。通过引进由流动引起的浓度波动项,利用最小过冷度理论推导出了下式:λ~2V=Ao/(1-A~1Guλ~2/D)。式中Gu=0. 25~μ-0.5~ωl- 5~r,Gu为液固界面前的速度梯度。随半径r增加而增加,这就较好地解释了层片间距λ与r的关系。此外,在试棒的外侧还发现了锡富集层。
In this paper, the influence of electromagnetic stirring on the ply structure of pb-Sn eutectic alloy under directional solidification condition was studied. The results showed that the eutectic Pb-Sn alloy coarsened significantly, and the spacing between the layers increased with the increase of the radius. By introducing the flow-induced concentration fluctuations, the following equation is derived using the theory of minimum undercooling: λ ~ 2V = Ao / (1-A ~ 1Guλ ~ 2 / D). Where Gu = 0.25 ~ μ-0.5 ~ ωl-5 ~ r, Gu is the velocity gradient in front of the liquid-solid interface. As the radius r increases, it increases, which better explains the relationship between the lamellar spacing λ and r. In addition, a tin-rich layer was found on the outside of the test bar.