Theoretical model for non-equilibrium solidification is constructed with consideration of diffuse interface and muliphase fhctuation.It can be degenerated to A(?)i(?) continuousgrowth model in the case of mono-atomic approximation.For large underecooling, thechange of heat eapacity should not be neglected and it usually gives an increase in the inter-face partition coefficient.Solute trapping may happen at a rather slow growth rate com-pared with that predicted by other models,because the undercooling and structural relaxa-tion ahead of the S/L interface lowers the interfacial diffusivity to a great extent. Phasefluctuation has two contending effects,decrease in energy barrier and increase in atomicdragging,therefore exerts dual influences on the partition coefficient.
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