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Search Publications by: James A. Warren (Fed)

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Displaying 26 - 50 of 94

Irreversible thermodynamics of creep in crystalline solids

November 15, 2013
Author(s)
Yuri Mishin, James A. Warren, Robert F. Sekerka, William J. Boettinger
We develop an irreversible thermodynamics framework for the description of creep deformation in crystalline solids by mechanisms that involve vacancy diffusion and lattice site generation and annihilation. The material undergoing the creep deformation is

A diffuse-interface Model of Reactive Wetting with Intermetallic Formation

May 1, 2012
Author(s)
Walter Villaneuva, William J. Boettinger, Geoffrey B. McFadden, James A. Warren
A diffuse-interface model of reactive wetting with intermetallic formation is developed that incorporates fluid flow, phase change, and solute diffusion. The model is based on the total molar Gibbs energy of a ternary system with four phases. Numerical

The Effect of Substrate Material on Silver Nanoparticle Antimicrobial Efficacy

December 1, 2010
Author(s)
Benita Dair, Dave M. Saylor, T. E. Cargal, Grace R. French, Kristen M. Kennedy, Rachel S. Casas, Jonathan E. Guyer, James A. Warren, Steven K. Pollack
With the advent of Nanotechnology, silver nanoparticles increasingly are being used in coatings, especially in medical device applications, to capitalize on their antimicrobial properties. The increased antimicrobial efficacy of nanoparticulate silver

Effect of Phase Change and Solute Diffusion on Spreading on a Dissolving Substrate

October 1, 2010
Author(s)
Walter Villanueva, William J. Boettinger, James A. Warren, Gustav Amberg
Dissolutive wetting is investigated numerically using a diffuse-interface model that incorporates fluid flow, solute diffusion, and phase change. A range of materials parameters are investigated that: 1) permits recovery of the hydrodynamic limit by

Predicting Microstructure Development During Casting of Drug Eluting Coatings

September 19, 2010
Author(s)
David M. Saylor, Jonathan E. Guyer, Daniel Wheeler, James A. Warren
We have devised a novel diffuse interface formulation to model the development of chem- ical and physical inhomogeneities, i.e. microstructure, during the process of casting drug eluting coatings. These inhomogeneities, which depend on the coating

Modeling Reactive Wetting when Inertial Effects are Dominant

June 30, 2010
Author(s)
Daniel Wheeler, James A. Warren, William J. Boettinger
Recent experimental studies of molten metal droplets wetting and spreading on high temperature reactive substrates have established that the majority of triple-line motion occurs when inertial effects are dominant. In light of these studies, this paper

A Multicomponent and Multiphase Model of Reactive Wetting

June 4, 2010
Author(s)
Walter Villanueva, William J. Boettinger, Geoffrey B. McFadden, James A. Warren
A diffuse-interface model of reactive wetting with intermetallic formation is presented. The model incorporates fluid flow, solute diffusion, and phase change that are based on the total molar Gibbs energy of a ternary system with four phases. Numerical

Grain boundaries exhibit the dynamics of glass-forming liquids

May 12, 2009
Author(s)
James A. Warren, Jack F. Douglas, Xuhang Tong, David J. Srolovitz
Polycrystalline materials are composites of crystalline particles or grains separated by thin amorphous grain boundaries (GBs). Although GBs have been exhaustively investigated at low temperatures, at which these regions are relatively ordered, much less

FiPy: PDEs in Python

February 23, 2009
Author(s)
Jonathan E. Guyer, Daniel Wheeler, James A. Warren
Partial differential equations (PDEs) are ubiquitous to the mathematical description of physical phenomena. They describe the relationships between functions of more than one independent variable and partial derivatives with respect to those variables

Phase Field Approach to Heterogeneous Crystal Nucleation in Alloys

January 11, 2009
Author(s)
James A. Warren, T Pusztai, L Kornyei, L Granasy
We extend the phase field model of heterogeneous crystal nucleation developed recently [L. Granasy, T. Pusztai, D. Saylor, and J. A. Warren, Phys. Rev. Lett. 98, 035703 (2007)] to binary alloys. Three approaches are considered to incorporate foreign walls

A Finite Volume PDE Solver Using Python (FiPy)

October 16, 2008
Author(s)
Jonathan E. Guyer, Daniel Wheeler, James A. Warren
We present an object oriented partial differential equation (PDE) solver written in Python based on a standard finite volume (FV) approach.The solution of coupled sets of PDEs is ubuquitous in the numerical simulation of science problems. Numerous PDE

Computational Materials Science and Industrial R&D: Accelerating Progress

October 16, 2008
Author(s)
S C. Glotzer, James A. Warren
Computtional materials research has made major advances over the past decade in accelerating the design, processing and performance of technologically important materials. materials simulation is, however, still in its infancy, as the nature of mateirals

Nature Materials News and Views on T. Haxhimali et al

October 16, 2008
Author(s)
James A. Warren
Simulations of dendritic solidification by T. Haxhimali et al. [1] for a pure material and comparisons with experiments in an A1Zn alloy system have shown that a standard theoretical rule of thumb for predicting solidification growth forms can dramatically

An Efficient Algorithm for Solving the Phase Field Crystal Model

June 1, 2008
Author(s)
Mowei Cheng, James A. Warren
We present and discuss the development an unconditionally stable algorithm to solving the evolution equations for the Phase Field Crystal (PFC) model. This algorithm allows for an arbitrarily large algorithmic time step. As the basis for our analysis of

Atomic Motion During the Migration of General [001] Tilt Grain Boundaries in Ni

August 24, 2007
Author(s)
Hao Zhang, David J. Srolovitz, Jack F. Douglas, James A. Warren
We generalize a previous study of the atomic motions governing grain boundary migration to consider arbitrary misorientations of [001] tilt boundaries. Our examination of the nature of atomic motions employed three statistical measures: the non-Gaussian

Phase Field Theory of Heterogeneous Crystal Nucleation

January 19, 2007
Author(s)
L Granasy, T Pusztai, D M. Saylor, James A. Warren
A phase field approach is developed to model wetting and heterogeneous crystal nucleation of an undercooled pure liquid in contact with a sharp wall. We discuss various choices for the boundary condition at the wall and determine the properties of critical

Accuracy of Unconditionally Stable Algorithms in Cahn-Hilliard Systems

January 11, 2007
Author(s)
Mowei Cheng, James A. Warren
Given an unconditionally stable algorithm for solving the Cahn-Hilliard equations, we provide the mathematical basis for arbitrary accuracy -- we present a general calculation for an analytical time step Δ Tau in terms of an algorithmic time step Δ Tau. By

Characterization of Atomic Motions Governing Grain Boundary Migration

September 24, 2006
Author(s)
Hao Zhang, David J. Srolovitz, Jack F. Douglas, James A. Warren
Molecular dynamics simulations were employed to study atomic motion within stationary and migrating asymmetric tilt grain boundaries. We employ several measures of the complexity of the atomic trajectories, including the van Hove correlation function, the

Numerical Modeling of Diffusion-Induced Deformation

September 11, 2006
Author(s)
J A. Dantzig, William J. Boettinger, James A. Warren, Geoffrey B. McFadden, Sam R. Coriell, R F. Sekerka
We present a numerical approach to modeling the deformation induced the the Kirkendall effect in binary alloys. The governing equations for isothermal binary diffusion are formulated with respect to inert markers and also with respect to the volume

Polycrystalline Patterns in Far-From-Equilibrium Freezing: A Phase Field Study

August 1, 2006
Author(s)
L Granasy, T Pusztai, T Borzsonyi, G Toth, G -. Tegze, James A. Warren, Jack F. Douglas
We discuss the formation of polycrystalline microstructures with the framework of phase field theory. First, the model is tested for crystal nucleation in a hard sphere system. It is shown that, when evaluating the model parameters from molecular dynamics
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