A model of grain growth in UN integrating molecular dynamics, phase-field modeling, and uncertainty quantification
Abstract
Grain growth kinetics and grain-boundary (GB) properties in uranium mononitride (UN) are investigated through an integrated multiscale framework combining molecular dynamics (MD), phase-field modeling, and surrogate-assisted uncertainty quantification. MD simulations yield GB energies for 27 symmetric tilt boundaries from 0--2000~K, which are consistent with available DFT values. The average GB energy is nearly temperature-independent below 1000~K and increases at higher temperatures. A mechanistic pore-drag model applied to the only available grain growth dataset for actinide nitrides yields a mobility reduction factor of s ≈ 0.93--$0.99$, statistically indistinguishable from unity, confirming that pore drag is negligible under the experimental conditions. The intrinsic GB mobility is therefore extracted directly from the effective mobility, yielding M0 = 2.05×10−15~m4/(J·s) and QM = 0.89~eV. Phase-field simulations conducted from 1500--2000~K confirm normal curvature-driven grain growth, with grain size distributions converging to the Hillert-like form. A surrogate-assisted global sensitivity analysis---combining principal component analysis, Gaussian process regression, and Sobol decomposition---reveals that the mobility prefactor M0 dominates output variance at all times, followed by the activation energy QM, while the GB energy γ contributes minimally. These results establish the first quantitative grain growth framework for UN and identify the reduction of uncertainty in M0 and QM as the highest-priority target for future experimental efforts.
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BibTeX
@misc{abdulhameed2026model,
title = {{A model of grain growth in UN integrating molecular dynamics, phase-field modeling, and uncertainty quantification}},
author = {Mohamed AbdulHameed and Fadel M. Nasr and Wen Jiang and Mahmoud Yaseen and Benjamin Beeler},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.10977},
eprint = {2609.10977},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.10977},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A model of grain growth in UN integrating molecular dynamics, phase-field modeling, and uncertainty quantification
AU - Mohamed AbdulHameed
AU - Fadel M. Nasr
AU - Wen Jiang
AU - Mahmoud Yaseen
AU - Benjamin Beeler
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.10977
UR - https://arxiv.org/abs/2609.10977
AB - Grain growth kinetics and grain-boundary (GB) properties in uranium mononitride (UN) are investigated through an integrated multiscale framework combining molecular dynamics (MD), phase-field modeling, and surrogate-assisted uncertainty quantification. MD simulations yield GB energies for 27 symmetric tilt boundaries from 0--2000~K, which are consistent with available DFT values. The average GB energy is nearly temperature-independent below 1000~K and increases at higher temperatures. A mechanistic pore-drag model applied to the only available grain growth dataset for actinide nitrides yields a mobility reduction factor of s ≈ 0.93--$0.99$, statistically indistinguishable from unity, confirming that pore drag is negligible under the experimental conditions. The intrinsic GB mobility is therefore extracted directly from the effective mobility, yielding M_0 = 2.05×10^−15~m^4/(J·s) and Q_M = 0.89~eV. Phase-field simulations conducted from 1500--2000~K confirm normal curvature-driven grain growth, with grain size distributions converging to the Hillert-like form. A surrogate-assisted global sensitivity analysis---combining principal component analysis, Gaussian process regression, and Sobol decomposition---reveals that the mobility prefactor M_0 dominates output variance at all times, followed by the activation energy Q_M, while the GB energy γ contributes minimally. These results establish the first quantitative grain growth framework for UN and identify the reduction of uncertainty in M_0 and Q_M as the highest-priority target for future experimental efforts.
ER -