Computer Simulation of Final‐Stage Sintering: I, Model Kinetics, and Microstructure

Hassold, Gregory N.; Chen, I‐Wei; Srolovitz, David J.

doi:10.1111/j.1151-2916.1990.tb06686.x

Cited by 120 publications

(60 citation statements)

References 22 publications

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“…If the viscous moduli are constant on some interval (27) is reduced to which can be used for approximating the real non-linear dependence of the viscous moduli on microstructural parameters by piecewise constant functions. Assuming that we can have enough points inside the interval [ t o r t , ] that we can form as many equations as needed to calculate all the required components of the moduli tensorix, we can then determine the sintering stress from (25).…”

Section: Summation In a Repeating Index Is Implied VI What Happens Ifmentioning

confidence: 99%

Microstructural and continuum evolution modeling of sintering.

Braginsky¹,

Olevsky²,

Johnson

et al. 2003

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All ceramics and powder metals, including the ceramics components that Sandia uses in critical weapons components such as PZT voltage bars and current stacks, multilayer ceramic MET'S, ahmindmolybdenum & alumina cermets, and ZnO varistors, are manufactured by sintering. Sintering is a critical, possibly the most important, processing step during manufacturing of ceramics. The microstructural evolution, the macroscopic shrinkage, and shape distortions during sintering will control the engineering performance of the resulting ceramic component. Yet, modeling and prediction of sintering behavior is in its infancy, lagging far behind the other manufacturing models, such as powder synthesis and powder compaction models, and behind models that predict engineering properties and reliability. In this project, we developed a model that was 3 capable of simulating microstructural evolution during sintering, providing constitutive equations for macroscale simulation of shrinkage and distortion during sintering. And we developed macroscale sintering simulation capability in JAS3D.The mesoscale model can simulate microstructural evolution in a complex powder compact of hundreds or even thousands of particles of arbitrary shape and size by 1. curvature-driven grain growth, 2. pore migration and coalescence by surface diffusion, 3. vacancy formation, grain boundary difhsion and annihilation. This model was validated by comparing predictions of the simulation to analytical predictions for simple geometries. The model was then used to simulate sintering in complex powder compacts. Sintering stress and materials viscous moduli were obtained from the simulations. These constitutive equations were then used by macroscopic simulations for simulating shrinkage and shape changes i n FEM simulations.The continuum theory of sintering embodied in the constitutive description of Skorohod and Olevsky was combined with results from microstructure evolution simulations to model shrinkage and deformation during. The continuum portion is based on a finite element formulation that allows 3D components to be modeled using SNL's nonlinear large-deformation finite element code, JAS3D. This tool provides a capability to model sintering of complex three-dimensional components. The model was verified by comparing to simulations results published in the literature. The model was validated using experimental results from various laboratory experiments performed by Garino. In addition, the mesoscale simulations were used to study anisotropic shrinkage in aligned, elongated powder compacts. Anisotropic shrinkage occurred in all compacts with aligned, elongated particles. However, the direction of higher shrinkage was in some cases along the direction of elongation and in other cases in the perpendicular direction depending on the details of the powder compact. In compacts of simplepacked, mono-sized, elongated particles, shrinkage was higher in the direction of elongation. In compacts of close-packed, mono-sized, elongated particles and of elonga...

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Section: Summation In a Repeating Index Is Implied VI What Happens Ifmentioning

confidence: 99%

Microstructural and continuum evolution modeling of sintering.

Braginsky¹,

Olevsky²,

Johnson

et al. 2003

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“…The sintering characteristics that can be investigated by using Monte Carlo simulations are microstructural evolution, grain growth, and grain size distribution. Braginsky et al 9) and Hassold, et al 10) developed certain models that used Monte Carlo simulations to simulate certain microstructure evolutions such as pore shrinkage, grain growth, pore breakaway during sintering. Neural networks are composed of simple elements which operate in parallel.…”

Section: )mentioning

confidence: 99%

A comparative study of different sintering models for Al<sub>2</sub>O<sub>3</sub>

Nguyen

Sistla

Kempen

et al. 2016

J. Ceram. Soc. Japan

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Based on various deformation mechanisms occurring during solid state sintering (pressureless and pressure assisted), a multitude of sintering models have been developed and presented in literature. As reported in literature, most of the simulation results line up well with experimental data. Unfortunately, none of them can be used arbitrarily and none of them are applicable to a generalized case. This paper focuses on a comparative study of three commonly applied models. The first model is based on a physical approach (Riedel) and the other two are phenomenologically based models (the modified SkorohodOlevsky Viscous Sintering (SOVS) model and a modified Abouaf model). The material models have been implemented through FORTRAN Subroutines used for the FE-Software ABAQUS. The simulation results demonstrate their advantages and disadvantages based on sintering simulations of an aluminum oxide based ceramic cylinder and a bilayer laminate. A guideline to select a suitable model and the adjustment of input parameters under different sintering conditions for general usage is also discussed.

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“…They are easy to code, readily extendable from two dimensions to three dimensions (2-D to 3-D), and can simulate the underlying physics of many materials evolution processes based on the statistical-mechanical nature of the model. These processes include curvature-driven grain growth [52,53], anisotropic grain growth [54], recrystallization [55], grain growth in the presence of a pinning phase [56,57], Ostwald ripening [58][59][60], and particle sintering [11,[61][62][63].…”

Section: Assessment Of the Thermodynamic Parametersmentioning

confidence: 99%

Mesoscale Benchmark Demonstration Problem 1: Mesoscale Simulations of Intra-granular Fission Gas Bubbles in UO2 under Post-irradiation Thermal Annealing

Li¹,

Hu²,

Montgomery³

et al. 2012

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SUMMARYA study was conducted to evaluate the capabilities of different numerical methods used to represent microstructure behavior at the mesoscale for irradiated material using an idealized benchmark problem. The purpose of the mesoscale benchmark problem was to provide a common basis for assessing several mesoscale methods to identify the strengths and areas of improvement in the predictive modeling of microstructure evolution. In this work, mesoscale models (phase-field, Potts, and kinetic Monte Carlo) developed by Pacific Northwest National Laboratory, Idaho National Laboratory, Sandia National Laboratory, and Oak Ridge National Laboratory were used to calculate the evolution kinetics of intragranular fission gas bubbles in UO 2 fuel under post-irradiation thermal annealing conditions. The benchmark problem was constructed to include important microstructural evolution kinetics of intragranular fission gas bubble behavior, such as the atomic diffusion of Xe atoms, U vacancies, and O vacancies; the effect of vacancy capture and emission from defects; and the elastic interaction on nonequilibrium gas bubbles. An idealized set of assumptions and a common set of thermodynamic and kinetic data were imposed on the benchmark problem to simplify the mechanisms considered. The modeling capabilities of different methods are compared against selected experimental and simulation results. These comparisons find that while the phase-field methods and Potts kinetic Monte Carlo methods are able to incorporate several of the mechanisms that influence intra-granular bubble growth and coarsening, the Potts model is challenged by the low solubility and long-range diffusion necessary to simulate this problem correctly. The statistical-mechanical nature of Potts kMC requires large ensembles with long simulation times to treat this problem. Future efforts are recommended to construct increasingly more complex mesoscale benchmark problems to further verify and validate the predictive capabilities of the mesoscale modeling methods used in this study.

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Computer Simulation of Final‐Stage Sintering: I, Model Kinetics, and Microstructure

Cited by 120 publications

References 22 publications

Microstructural and continuum evolution modeling of sintering.

Microstructural and continuum evolution modeling of sintering.

A comparative study of different sintering models for Al<sub>2</sub>O<sub>3</sub>

Mesoscale Benchmark Demonstration Problem 1: Mesoscale Simulations of Intra-granular Fission Gas Bubbles in UO2 under Post-irradiation Thermal Annealing

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