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Summary: Experimental constraints on nonequilibrium interface kinetic models
Michael J. Aziz
Division of Engineering and Applied Sciences, Harvard University, Cambridge MA 02138, USA
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Abstract
Experimental results relevant to models for nonequilibrium interface kinetics during rapid solidification are reviewed. Models are
examined critically in light of these experiments. The kinetic Ising model is shown to compare unfavorably with experiment. The
Continuous Growth Model without solute drag and its extension to non-(001) interfaces, the Aperiodic Stepwise Growth Model, account
well for all relevant experimental results.
Keywords: rapid solidification, undercooling, solute trapping
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1. Introduction
When rapid solidification occurs, deviations from local
interfacial equilibrium become readily apparent. Solute trapping
occurs: k, the ratio of solute concentration in the solid to that in
the liquid at the interface, deviates from its equilibrium value and
approaches unity. Kinetic undercooling occurs: the crystal/melt
interface becomes undercooled with respect to the equilibrium
liquidus temperature for the liquid composition at the interface.
The objective of nonequilibrium interface kinetic models is to
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