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Search Publications by: Geoffrey B. McFadden (Assoc)

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Displaying 51 - 75 of 96

Phase Field Modeling of Electrochemistry. II. Kinetics

February 1, 2004
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
The kinetic behavior of the phase field model described in (J.E. Guyer, W.J. Boettinger, J.A. Warren and G. B. McFadden, Phase field modeling of electrochemistry: Equilibrium, unpublished) is explored for advancing (plating) and receding (corroding)

The Effect of Anisotropic Surface Energy on the Rayleigh Instability

October 1, 2003
Author(s)
Katharine F. Gurski, Geoffrey B. McFadden
We determine the linear stability of a rod or wire subject to capillary forces arising from an anisotropic surface energy. The rod is assumed to be smooth with a uniform cross section given by a 2-D equilibrium shape. The stability analysis is based on

Influence of a Catalytic Surfactant on Roughness Evolution During Film Growth

July 24, 2003
Author(s)
Daniel Wheeler, Thomas P. Moffat, Geoffrey B. McFadden, Sam R. Coriell, Daniel Josell
celerator Coverage (CEAC) based mechanism for the impact of additives on the evolution of surface roughness is explained; the CEAC mechanism accounts for the conservation of locl coverage of adsorbed catalyst on a deforming interface. It has recently been

A Mechanism for Brightening: Linear Stability Analysis of the Curvature Enhanced Coverage Model

January 6, 2003
Author(s)
Geoffrey B. McFadden, Sam R. Coriell, Thomas P. Moffat, Daniel Josell, Daniel Wheeler, W Schwarzacher
This work presents experiments and theory describing a mechanism for how brighteners in electrolytes function. The mechanism involves change of local coverage of a deposition rate enhancing catalyst adsorbed on the surface through change of local surface

Phase-Field Models of Solidification

November 1, 2002
Author(s)
Geoffrey B. McFadden
Phase-field models of solidification are presented in the context of diffuse-interface theories based on conserved and non-conserved Order parameters. Phase-field models for single-component materials are derived, and the sharp interface limits that relate

Convective and Morphological Instabilities During Crystal Growth

June 1, 2002
Author(s)
Geoffrey B. McFadden, Sam R. Coriell, B T. Murray
During crystal growth or solidification of a binary alloy from a liquid phase, temperature and solute gradients are inherently present and can give rise to fluid flow in the melt. The interaction of fluid flow with the crystal-meltinterface plays an

On the Gibbs Adsorption Equation and Diffuse Interface Models

May 1, 2002
Author(s)
Geoffrey B. McFadden, A A. Wheeler
In this paper we discuss some applications of the classical Gibbs adsorption equations to specific diffuse interface models that are based on conserved and non-conserved order parameters. Such models are natural examples of the general methodology

Phase Field Modeling Applied to the Double Layer

May 1, 2002
Author(s)
Jonathan E. Guyer, William J. Boettinger, James A. Warren, Geoffrey B. McFadden
We present the first application of phase field modeling to electrochemistry. A free energy functional that includes the electrostatic effect of charged particles leads to rich interactions between concentration, electrostatic potential, and phase

Applications of Morphological Stability Theory

April 1, 2002
Author(s)
Sam R. Coriell, Geoffrey B. McFadden
Recent applications of mormhological stability theory are reviewed. For growth of a binary alloy from the melt, the temperature-dependence of the solute diffusivity can have a significant effect on the critical wavelength at the onset of instability. The

Model of Electrochemical Double Layer" Using the Phase Field Method

March 20, 2002
Author(s)
William J. Boettinger, Geoffrey B. McFadden, James A. Warren, Jonathan E. Guyer
We present the first application of phase field modeling to electrochemistry. A free energy functional that includes the electrostatic effect of charged particles leads to rich interactions between concentration, electrostatic potential, and phase

A Phase-Field Model of Convection with Solidification

January 1, 2002
Author(s)
D M. Anderson, Geoffrey B. McFadden, A A. Wheeler
A phase-field model for the solidification of a pure material that incorporates convection has recently been developed. This model is a two-fluid model in which the solid phase is modeled as a sufficiently viscous fluid. The model allows for the solid and

Separation of Scales for Growth of an Alloy Needle Crystal

October 1, 2001
Author(s)
R F. Sekerka, Sam R. Coriell, Geoffrey B. McFadden
We reexamine the problem of a needle crystal (a model for a dendrite primary stalk) having the shape of a paraboloid of revolution growing at constant velocity from a supercooled binary alloy with given bulk concentration and far-field temperature. The

A Phase-Field Model With Convection: Sharp-Interface Asymptotics

May 1, 2001
Author(s)
D M. Anderson, Geoffrey B. McFadden, A A. Wheeler
We have previously developed a phase-field model of solidification that includes convection in the melt. This model represents the two phases as viscous liquids, where the putative solid phase has a viscosity much larger than the liquid phase. The object

Effect of Flow Due to Density Change on Eutectic Growth

April 1, 2001
Author(s)
Sam R. Coriell, Geoffrey B. McFadden, William F. Mitchell, B T. Murray, J B. Andrews, Y B. Arikawa
The Jackson-Hunt model of eutectic growth is extended to allow for different densities of the phases. The density differences give rise to fluid flow which is calculated from a series solution of the fluid flow equations in the Stokes flow approximation

A Phase-Field Model for Highly Anisotropic Interfacial Energy

March 1, 2001
Author(s)
J J. Eggleston, Geoffrey B. McFadden, P W. Voorhees
A computationally efficient phase-field model is developed for two-phase systems with anisotropic interfacial energy. The approach allows for anisotropies sufficiently high that the interface has corners or missing crystallographic orientations. The method

On the Gibbs Adsorption Equation for Diffuse Interface Models

March 1, 2001
Author(s)
Geoffrey B. McFadden, A A. Wheeler
In this paper we discuss some applications of the classical Gibbs adsorption equations to specific diffuse interface models that are based on conserved and non-conserved order parameters. Such models are natural examples of the general methodology

A Phase-Field Model for High Anisotropic InterfaciEnergy

January 1, 2001
Author(s)
Geoffrey B. McFadden, J J. Eggleston, P W. Voorhees
A computationally efficient phase-field model is developed for two-phase systems with anisotropic interfacial energy. The approach allows for anisotropies sufficiently high that the interface has corners or missing crystallographic orientations. The method

A Phase-Field Model With Convection: Numerical Simulations

December 1, 2000
Author(s)
D M. Anderson, Geoffrey B. McFadden, A A. Wheeler
In a previously developed phase-field model of solidification that includes convection in the melt, the two phases are represented as viscous liquids, where the putative solid phase has a viscosity much larger than the liquid phase. In this paper we report

Morphological Stability of a Binary Alloy: Temperature-Dependent Diffusivity

November 1, 2000
Author(s)
Sam R. Coriell, Geoffrey B. McFadden, S R. Vanaerenbergh
The effect of the temperature dependence of the diffusion coefficient on the morphological stability of a binary alloy during directional solidification is treated by a linear stability analysis. The Soret effect is also included in the analysis. Specific

The Effect of Oscillatory Shear Flow on Step Bunching

September 1, 2000
Author(s)
B T. Murray, Sam R. Coriell, A A. Chernov, Geoffrey B. McFadden
During crystal growth, an imposed shear flow at the crystal-fluid interface can impact the conditions for the onset of morphological instability. In previous work, we studied the effect of time-independent shear flows and anisotropic interface kinetics on

Effect of Surface Free Energy Anisotropy on Dendrite Tip Shape

July 1, 2000
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

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