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Displaying 151 - 175 of 193

Microsegregation in Peltier Interface Demarcation

July 1, 2000

Author(s)

Y Dabo, H N. Thi, Sam R. Coriell, Geoffrey B. McFadden, Q Li, B Billia

Experimental results on solute microsegregation induced by Peltier Interface Demarcation (PID) technique during directional solidification of Bi-1 wt % Sb alloys are presented. These data are compared with the results of numerical simulation and the theory

A Phase-Field/Fluid Motion Model of Solidification: Investigation of Flow Effects During Directional Solidification and Dendritic Growth

June 1, 2000

Author(s)

D M. Anderson, William J. Boettinger, Geoffrey B. McFadden, A A. Wheeler

The phase-field model of diffusion-controlled solidification has recently been extended to include the effects of fluid flow in the melt. The phase-field model is based on coupling the equations for heat flow in the liquid and solid phases with an

Convective and Morphological Instabilities During Crystal Growth

June 1, 2000

Author(s)

Sam R. Coriell, Geoffrey B. McFadden, B T. Murray

We have studied the effects of interface morphology on the dynamics of dendritic growth. The Ivantsov solution for an isothermal paraboloid of revolution growing into a pure, supercooled melt provides a relation between the bulk supercooling and a

On the Properties of Alpha/Alpha + Beta Diffusion Couples

January 1, 2000

Author(s)

William J. Boettinger, Sam R. Coriell, Carelyn E. Campbell, Geoffrey B. McFadden

The properties of diffusion couples in a ternary system are examined theoretically when one end member is composed of single-phase material (alpha) and the other end member is composed of two-phase material (α + Β). Using the model of Morral and co-workers

Thin Interface Asymptotics for an Energy/Entropy Approach to Phase-Field Models with Unequal Conductivities

September 1, 1999

Author(s)

Geoffrey B. McFadden, A A. Wheeler, D M. Anderson

Karma and Rappel (1) recently developed a new sharp interface asymptotic analysis of the phase-field equations that is especially appropriate for modeling dendritic growth at low undercoolings. Their approach relieves a stringent restriction on the

Effect of Surface Free Energy Anisotrophy on Dendrite Tip Shape

August 1, 1999

Author(s)

Richard J. Braun, J Zhang, John W. Cahn, Geoffrey B. McFadden, A A. Wheeler

We describe a mean field, free energy model that allows the computation of realistic phase diagrams for a particular set of ordering transitions in face-centered-cubic (FCC) binary alloys. The model is based on a sixth-order Landau expansion of the free

Shape Parameter for a Non-Axisymmetric Isothermal Dendrite

June 1, 1999

Author(s)

Geoffrey B. McFadden, Sam R. Coriell, R F. Sekerka

In previous work, we found approximate solutions for paraboloids having perturbations with four-fold axial symmetry in order to model dendritic growth in cubic materials. These solutions provide self-consistent corrections through second order in a shape

Steps, Kinetic Anisotropy, and Long Wavelength Instabilities in Directional Solidification

May 1, 1999

Author(s)

H P. Grimm, S H. Davis, Geoffrey B. McFadden

We consider the effect of anisotropic kinetics on long-wavelength instabilities during the directional solidification of a binary alloy having a vicinal interface. Linear theory predicts that a planar solidification front is stabilized under the effect of

Selection Mechanisms for Multiple Similarity Solutions for Solidification and Melting

April 1, 1999

Author(s)

Sam R. Coriell, Geoffrey B. McFadden, R F. Sekerka

When a solid phase of uniform temperature Ts∞ and Composition Cs∞ is brought into contact with a liquid phase of uniform temperature TL∞ and composition CL∞, there exist similarity solutions for which the position X of the solid-liquid interface is

A Phase-Field Model of Solidification With Convection

March 1, 1999

Author(s)

D M. Anderson, Geoffrey B. McFadden, A A. Wheeler

We develop a phase-field model for the solidification of a pure material that includes convection in the liquid phase. The model permits the interface to have an anisotropic surface energy, and allows a quasi-incompressible thermodynamic description in

Analytic Solution for a Non-Axisymmetric Isothermal Dendrite

March 1, 1999

Author(s)

Geoffrey B. McFadden, Sam R. Coriell, R F. Sekerka

The Ivantsov solution for an isothermal paraboloidal dendrite growing into a pure, undercooled melt provides a relation between the bulk undercooling and a dimensionless product, the Peclet number, of the growth velocity and tip radius of the dendrite

A Phase-Field Model of Solidification with Convection

September 1, 1998

Author(s)

D M. Anderson, W J. Boettinger, Geoffrey B. McFadden, A A. Wheeler

Anisotropy of Interfaces in an Ordered HCP Binary Alloy

September 1, 1998

Author(s)

John W. Cahn, S C. Han, Geoffrey B. McFadden

A multiple-order parameter mean field theory of ordering on a binary hexagonal-close-packed (HCP) crystal structure is developed, and adapted to provide a continuum formulation that incorporates the underlying symmetries of the HCP crystal in both the bulk

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