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金属学报  2005, Vol. 41 Issue (9): 917-922     
  论文 本期目录 | 过刊浏览 |
侧向凝固通道偏析的数值模拟
曹海峰 沈厚发 柳百成
清华大学机械工程系;北京 100084; 清华大学先进成形制造重点实验室; 北京 100084
NUMERICAL SIMULATION OF SEGREGATION IN CHANNEL DURING HORIZONTAL SOLIDIFICATION
CAO Haifeng; SHEN Houfa; LIU Baicheng
Department of Mechanical Engineering; Tsinghua University; Beijing 100084;Key Laboratory for Advanced Manufacturing by Materials Processing Technology; Tsinghua University; Beijing 100084
引用本文:

曹海峰; 沈厚发; 柳百成 . 侧向凝固通道偏析的数值模拟[J]. 金属学报, 2005, 41(9): 917-922 .
, , . NUMERICAL SIMULATION OF SEGREGATION IN CHANNEL DURING HORIZONTAL SOLIDIFICATION[J]. Acta Metall Sin, 2005, 41(9): 917-922 .

全文: PDF(290 KB)  
摘要: 建立了二元系凝固过程通道偏析形成的数学模型,给出了描述焓与温度及固相分数耦合关系的表达式. 在实验验证的基础上,对亚共晶与过共晶成分的NH4Cl-H2O侧向凝固通道偏析的形成位置与生长方向进行了数值模拟研究. 模拟计算结果表明,偏析通道起源于糊状区,偏析通道中的富集溶质从糊状区流向液相区. 为了维持偏析通道中的液体流动,枝晶间液体可通过糊状区从液相区得到补充. 糊状区中富集溶质的流动方向取决于析出溶质的密度. NH4Cl-70%H2O侧向凝固时,析出的溶质密度较小,偏析通道倾斜向上生长,在糊状区上部形成A偏析. NH4Cl-90%H2O侧向凝固时,析出的溶质密度较大,在糊状区下部偏析通道倾斜向下生长.
关键词 凝固通道偏析数值模拟     
Abstract:A mathematical model for the segregation formation in channel during solidification process of binary alloys has been built and a set of expressions coupling the temperature and solid fraction with enthalpy is determined. The formation position and growth direction of the segregation during the horizontal solidification of NH4Cl-H2O with hypoeutectic and hypereutectic compositions are numerically studied based on the experiment. The simulation results show that the segregation originates from the mushy zone and the solute-rich liquid flows from mush into liquid. In order to supply the mass equilibrium in the channels,the fresher liquid may penetrate via the mushy zone from pure liquid region. The flow direction of solute-rich liquid in mush depends on its density. Because of the lower density of the rejected solute during the horizontal solidification of NH4Cl-70%H2O, channels grow slantways and upwards and A type segregates form in the upper region of mush. While the density of the rejected solute during the horizontal solidification of NH4Cl-90%H2O, channels grow slantways and downwards in the lower region of mush.
Key wordssolidification    segregation in channel    numerical simulation
收稿日期: 2005-01-28     
ZTFLH:  TG244  
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