垂直定向凝固条件下通道偏析形成过程的数值模拟  

NUMERICAL SIMULATION ON CHANNEL SEGREGA- TION IN VERTICALLY UNIDIRECTIONAL SOLIDIFICATION PROCESS

作　　者：韩志强[1] 柳百成[1] 

机构地区：[1]清华大学机械工程系

出　　处：《金属学报》2003年第2期140-144,共5页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展规划G2000067208-3;中国博士后科学基金资助项目

摘　　要：建立了描述合金凝固过程热,溶质对流和宏观偏析形成过程的教学模型,模型中耦合求解了凝固过程中质量、动量.能量和溶顷守恒方程;同时,基于固液两相区中温度和成分的耦合关系建立了固相分数场的更新方法.利用该模型模拟了底部冷却的三维矩形区域内Fe-C合金凝固过程中通道偏析的形成和发展过程。模拟结果表明,垂直定向凝固条件下通道偏析形成于液相线前沿附近,而不是两相区内部.这一结果很好地支持厂文献中基于实验观察提出的通道偏析形成机理.A mathematical model for describing the thermosolutal convection and macrosegregation evolution in solidification of multicomponent alloys is developed, in which the macroscopic mass, momentum, energy and species conservation equations are solved simultaneously. The solid fraction field is updated by using an approach based on complete coupling of the temperature and concentration through thermodynamic equilibrium in the mushy zone. By using this model, the origination and evolution of channel segregation in solidification of a Fe-C alloy in a bottom-chilled two-dimensional rectangular domain are numerically simulated. The simulation results show that in vertically unidirectional solidification process the channel segregation originates near the liquid us front instead of in the mushy zone, which supports the proposed formation mechanism of the segregation based on experimental observations.

关 键 词：FE-C合金 定向凝固 热-溶质对流 通道偏析 数值模拟 

分 类 号：TG111.4[金属学及工艺—物理冶金] TB115[金属学及工艺—金属学]