A strongly nonlinear-analysis of the morphological instability of a freezing binary alloy - solutal convection, density change, and nonequilibrium effects
A strongly nonlinear-analysis of the morphological instability of a freezing binary alloy - solutal convection, density change, and nonequilibrium effects
In this paper, amplitude equations for the development of morphological instability of a freezing binary alloy are derived using a strongly nonlinear analysis. The effects of density change in the system are considered. In particular, the density of the liquid phase is allowed to depend on its composition and to be different from that of the solid. Both necessarily give rise to convection in the melt when the system becomes unstable. It is found that such convection can act either to stabilize and promote supercritical behaviour or conversely to destabilize and promote subcritical behaviour, the precise behaviour being crucially dependent upon the relative densities of the solid and liquid phases. The effect of nonequilibrium segregation is also studied and it is shown that buoyancy-driven convection can act to favour the onset of instability through overstable modes.
Directional solidification, stability, segregation
173-192
Wheeler, A.A.
eb831100-6e51-4674-878a-a2936ad04d73
1991
Wheeler, A.A.
eb831100-6e51-4674-878a-a2936ad04d73
Wheeler, A.A.
(1991)
A strongly nonlinear-analysis of the morphological instability of a freezing binary alloy - solutal convection, density change, and nonequilibrium effects.
IMA Journal of Applied Mathematics, 47 (2), .
Abstract
In this paper, amplitude equations for the development of morphological instability of a freezing binary alloy are derived using a strongly nonlinear analysis. The effects of density change in the system are considered. In particular, the density of the liquid phase is allowed to depend on its composition and to be different from that of the solid. Both necessarily give rise to convection in the melt when the system becomes unstable. It is found that such convection can act either to stabilize and promote supercritical behaviour or conversely to destabilize and promote subcritical behaviour, the precise behaviour being crucially dependent upon the relative densities of the solid and liquid phases. The effect of nonequilibrium segregation is also studied and it is shown that buoyancy-driven convection can act to favour the onset of instability through overstable modes.
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Published date: 1991
Keywords:
Directional solidification, stability, segregation
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Local EPrints ID: 818
URI: http://eprints.soton.ac.uk/id/eprint/818
ISSN: 0272-4960
PURE UUID: 3f5f394f-d38f-4e23-9d1b-497ffd36ed4d
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Date deposited: 25 Mar 2004
Last modified: 11 Dec 2021 13:19
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Author:
A.A. Wheeler
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