Micro-Segregation along the Monovariant Line in a Ternary Eutectic Alloy System

Abstract

To investigate the solidification after a single-phase dendritic solidification of a ternary alloy or to develop the process for making in-situ composite of a ternary alloy, a micro-segregation model along the monovariant line has been introduced. The solidification mode accompanied with this micro-segregation model is assumed as cellular or dendritic eutectic solidification. This model assumes a partial diffusion in the solid; the diffusion of the first solute element in the first solid phase works completely or finitely but no other diffusions work in either solid. This is also a model of the solidification of an iron-carbon-metallic ternary alloy. Two kinds of formulations are made; the first is the general formulation between the solid compositions or the liquid compositions and the volume fractions of the two solids and the second is with a simplified phase diagram. Comparison of the results between Scheil-type solidification, complete diffusion of the first solute in the first phase and finite diffusion of the first solute in the first phase has been made for three cases of simplified phase diagrams. The affect of the solutal transition in the phase diagram has been demonstrated and the affect of diffusivities in the solid on the micro-segregation along the monovariant line has been illustrated.