The use of equilibrium phase diagram for the calculation of non-equilibrium precipitates in dendritic solidification. Theory

Abstract

New model for solute redistribution in cellular/dendritic growth has been applied to describe the amount of non-equilibrium precipitates. The model contains both extreme modes of solidification: the equilibrium solidification (lever rule) and the non-equilibrium solidification ( Scheil's model). The current theory is given in two steps: first, to describe the effect of partitioning on the behaviour of liquid and solid/liquid interface, next the effect of back-diffusion on the solute microsegregation and redistribution within the solid. The position on liquidus line when solidification is completed and an amount of non-equilibrium precipitates can be calculated. The phase diagram is used to show the location of the redistribution curve within the region contained between liquidus and solidus lines.