Effect of transport mechanism on the coarsening of bicontinuous structures: A comparison between bulk and surface diffusion

Andrews, W. Beck; Elder, Kate L. M.; Voorhees, Peter W.

doi:10.1103/physrevmaterials.4.103401

Cited by 12 publications

(4 citation statements)

References 58 publications

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“…The term doubly degenerate refers to the degeneracy in both the mobility and the stabilizing function. Although the role of the stabilizing function is not apparent from the asymptotics, it has been shown to perform better in numerical calculations [32,39,47,48]. Interestingly, a rescaling of Eqs.…”

Section: Fourth-order Conservative Equation [Cahn-hilliard (Ch) Equation]mentioning

confidence: 99%

Multiphase-field model for surface diffusion and attachment kinetics in the grand-potential framework

et al. 2021

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Grand-potential based multiphase-field model is extended to include surface diffusion. Diffusion is elevated in the interface through a scalar degenerate term. In contrast to the classical Cahn-Hilliard-based formulations, the present model circumvents the related difficulties in restricting diffusion solely to the interface by combining two second-order equations, an Allen-Cahn-type equation for the phase field supplemented with an obstacletype potential and a conservative diffusion equation for the chemical potential or composition evolution. The sharp interface limiting behavior of the model is deduced by means of asymptotic analysis. A combination of surface diffusion and finite attachment kinetics is retrieved as the governing law. Infinite attachment kinetics can be achieved through a minor modification of the model, and with a slight change in the interpretation, the same model handles the cases of pure substances and alloys. Relations between model parameters and physical properties are obtained which allow one to quantitatively interpret simulation results. An extensive study of thermal grooving is conducted to validate the model based on existing theories. The results show good agreement with the theoretical sharp-interface solutions. The obviation of fourth-order derivatives and the usage of the obstacle potential make the model computationally cost-effective.

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Section: Fourth-order Conservative Equation [Cahn-hilliard (Ch) Equation]mentioning

confidence: 99%

Multiphase-field model for surface diffusion and attachment kinetics in the grand-potential framework

et al. 2021

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“…Coarsening of nanoporous metals is often compared to simulations that coarsen computationally generated (CG) bicontinuous structures, e.g., those formed in simulations of spinodal decomposition (31). Evolution of these structures has been studied with phase-field (31)(32)(33)(34)(35) and kinetic Monte Carlo (KMC) (36)(37)(38) methods. In certain volume fraction ranges, particle detachment is observed during simulations of coarsening, altering the topology of the structure.…”

Section: Significancementioning

confidence: 99%

Grain boundary formation through particle detachment during coarsening of nanoporous metals

Elder

Andrews

Ziehmer

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Grain boundary formation during coarsening of nanoporous gold (NPG) is investigated wherein a nanocrystalline structure can form by particles detaching and reattaching to the structure. MicroLaue and electron backscatter diffraction measurements demonstrate that an in-grain orientation spread develops as NPG is coarsened. The volume fraction of the NPG sample is near the limit of bicontinuity, at which simulations predict that a bicontinuous structure begins to fragment into independent particles during coarsening. Phase-field simulations of coarsening using a computationally generated structure with a volume fraction near the limit of bicontinuity are used to model particle detachment rates. This model is tested by using the measured NPG structure as an initial condition in the phase-field simulations. We predict that up to ∼5% of the NPG structure detaches as a dealloyed Ag75Au25 sample is annealed at 300 °C for 420 min. The quantity of volume detached is found to be highly dependent on the volume fraction and volume fraction homogeneity of the nanostructure. As the void phase in the experiments cannot support independent particles, they must fall and reattach to the structure, a process that results in the formation of new grain boundaries. This particle reattachment process, along with other classic processes, leads to the formation of grain boundaries during coarsening in nanoporous metals. The formation of grain boundaries can impact a variety of applications, including mechanical strengthening; thus, the consideration and understanding of particle detachment phenomena are essential when studying nanoporous metals.

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“…For instance, continuum simulations (e.g. phase-field modeling 8 , 15 , 16 ) and atomistic simulations including kinetic Monte Carlo simulations 17 – 21 and molecular dynamics 22 , 23 model the morphological evolution during both dealloying and coarsening. Simulations also have offered a fundamental understanding of the processing–structure–property relationships such as explaining the atomistic origins on the anomalous compliance 23 and enhanced catalytic properties 17 .…”

Section: Introductionmentioning

confidence: 99%

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Liu

Ronne

et al. 2021

Nat Commun

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Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.

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Effect of transport mechanism on the coarsening of bicontinuous structures: A comparison between bulk and surface diffusion

Cited by 12 publications

References 58 publications

Multiphase-field model for surface diffusion and attachment kinetics in the grand-potential framework

Multiphase-field model for surface diffusion and attachment kinetics in the grand-potential framework

Grain boundary formation through particle detachment during coarsening of nanoporous metals

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

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