Estimation of Solute Concentration Distribution Accompanied by Interdendritic Solidification

Abstract

A peculiar break point in the cooling curves was experimentally observed. This point may be resulted from the rapid progress of solidification caused by the supercooling of interdendritic liquid.
For studying the mechanism mentioned above mathemaical models for estimating the distribution of the solute concentration in the interdendritic liquid have been developed. The models are described for three cases where the liquid-solid interface is plain, cylindrical surface, and spherical one, respectively. Two models for the second and the third cases, which represent the state of the liquid surrounded with the dendrite arms, show that the difference between the liquid concentrations at the liquid-solid interface and those at the midpoint of adjacent dendrites increase when the solid fraction increases at the constant ratio. And it may be understood that the concentration difference results in the supercooling. While for the first model the difference of the concentrations decreases.
Furthermore, by the use of the third model the measured temperatures where the break point occurs can be explained.