ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Phase-field study of solute trapping during rapid solidification of a binary diluted alloy

Date: 13.09.2011
Place: EUROMAT 2011 - European Congress on Advanced Materials and Processes, Montpellier, France

Ekaterina Abramova
Denis Danilov, Udmurt State University, Izhevsk, Russian Federation
Peter Galenko, Faculty of Physics and Astronomy, Deutsches Zentrum für Luft- und Raumfahrt, Köln, Germany
Dieter Herlach, Deutsches Zentrum für Luft- und Raumfahrt, Köln, Germany
Vladimir Lebedev, Udmurt State University, Izhevsk, Russian Federation

A phase-field model is developed to the case of rapid solidification in which local non-equilibrium phenomena occur in the bulk phases and within the diffuse solid-liquid interface. The model takes into account solute diffusion speed in bulk phases, characteristic scale of the solute diffusion speed within the diffuse interface, maximum speed of the diffuse interface and the velocity scale for the diffuse interface as four specific kinetic parameters. As a result, the model is described by a system of hyperbolic equations for the atomic diffusion transport as well as for the phase field. This model is applied to the problem of solute trapping, which is accompanied by the entrapment of solute atoms beyond chemical equilibrium by a rapidly moving interface. Solute concentration profiles, solute partitioning and kinetic phase diagrams are analyzed as a function of the solidification velocity.
The model predicts the beginning of complete solute trapping and diffusionless solidification at a finite solidification velocity equals the solute diffusion speed in bulk liquid. This result is analyzed in comparison with accessible experimental data and data of atomistic modelling on solute trapping by rapidly moving interfaces.

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