Grain Growth Kinetics in (Cr,Mo,Ta,V,W)C1-{\delta} High-Entropy Carbide Ceramics

Ali Sarikhani; Gregory E. Hilmas; David W. Lipke; Douglas E. Wolfe; Stefano Curtarolo; Shen J. Dillon; Ahmad Mirzaei; William G. Fahrenholtz

arXiv · 2604.08961

Grain Growth Kinetics in (Cr,Mo,Ta,V,W)C1-{\delta} High-Entropy Carbide Ceramics

Ali Sarikhani·Gregory E. Hilmas·David W. Lipke·Douglas E. Wolfe·Stefano Curtarolo·Shen J. Dillon·Ahmad Mirzaei·William G. Fahrenholtz

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Abstract

Understanding grain-boundary mobility during spark plasma sintering can enable microstructure control in high-entropy carbides, yet quantitative grain-growth kinetics remain scarce. In this work, grain growth kinetics and densification behavior were investigated for single-phase fully dense (Cr,Mo,Ta,V,W)C1-{\delta} high-entropy carbide ceramics. Specimens were densified by spark plasma sintering for a constant dwell time of 10 min at temperatures between 1750 {\deg}C and 1950 {\deg}C to isolate the role of temperature on microstructural evolution. Increasing sintering temperature produced grain growth and increased lattice parameter, while maintaining a single-phase rock salt structure. Elemental mapping showed a progressive reduction of Ta segregation with increasing sintering temperature, suggesting enhanced chemical homogenization at elevated temperatures. Grain growth kinetics were analyzed using a normal grain growth model with an assumed growth exponent of n=3, physically reasonable for grain-boundary-controlled growth influenced by solute and vacancy pinning. Arrhenius analysis of the growth factor yielded an apparent activation energy of approximately 620 kJ mol-1, comparable to diffusion-controlled processes in refractory transition-metal carbides. Densification curves revealed rapid consolidation prior to reaching the peak temperature followed by temperature-dominated grain coarsening. These results establish quantitative relationships between densification temperature, grain growth, and diffusion kinetics in a carbide system, providing insight into the microstructural stability of high-entropy, ultra-high-temperature carbide ceramics.

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Ali Sarikhani, Gregory E. Hilmas, David W. Lipke, Douglas E. Wolfe, Stefano Curtarolo, Shen J. Dillon, Ahmad Mirzaei, William G. Fahrenholtz. 2026-04-10. Grain Growth Kinetics in (Cr,Mo,Ta,V,W)C1-{\delta} High-Entropy Carbide Ceramics. https://arxiv.org/abs/2604.08961

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