Simulation of freckles during vertical solidification of binary alloys.

TLDR: In this article, a mathematical model of solidification that simulates the formation of channel segregates or freckles is presented, and the model is used to simulate the entire solidification process starting with the initial melt to the solidified cast.

Abstract: A mathematical model of solidification that simulates the formation of channel segregates or freckles is presented. The model simulates the entire solidification process starting with the initial melt to the solidified cast, and the resulting segregation is predicted. Emphasis is given to the initial transient, when the dendritic zone begins to develop and the conditions for the possible nucleation of channels are established. The mechanisms that lead to the creation and eventual growth or termination of channels are explained in detail and illustrated by several numerical examples. Predictions of the pattern and location of channels in different cooling situations are in good agreement with experimental observations.

Figures

Fig. 14: Formation and propagation of channels during growth of the mushy zone: Fraction liquid at (a) 2 min.; (b) 3 min.; (c) 5 min.; (d) 7 min.

Table II shows good agreement between the exact solution and the

Table II shows good agreement between the exact solution and the

Fig. 2: Pb-Sn phase diagram.

Fig. 6: Macrosegregation in horizontal solidification of NH4Cl-70 wt pct H20 solution. Total concentration (in

Fig. 19: Channel location in a tilted container.