NUMERICAL SIMULATION ON CHANNEL SEGREGATION IN VERTICALLY UNIDIRECTIONAL SOLIDIFICATION PROCESS
垂直定向凝固条件下通道偏析形成过程的数值模拟

A mathematical model for describing the thermosolutal convection and macrosegrega-tion 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 a.re numerically simulated. The simulation results show that in vertically unidirectional solidification process the channel segregation originates near the liquidus front instead of in the mushy zone, which supports the proposed formation mechanism of the segregation based on experimental observations.