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Ab-initio calculations, Debye-Wang model and thermodynamic modeling for the short-range order and crystal chemistry characterisation of the τ8-Al₂Fe₃Si₄ solid solution

Paul Lafaye, Kyota Poëti and Jean-Philippe Harvey

Article (2024)

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Abstract

This paper presents a comprehensive examination of the τ8-Al₂Fe₃Si₄ solid solution, investigating its crystal chemistry and short-range order. To do so, Density functional theory (DFT) calculations were performed, simulating partial substitutions of Al and Si on the four mixed sites of the structure. Our results indicates a negligible contribution from the SRO, allowing the Bragg–Williams approximation to be used to describe its crystal chemistry. Subsequently, systematic substitutions of Al and Si on all mixed sites generated a complete set of ordered structures, called end-members. The formation enthalpies, equation of state and elastic constants for each end-member were calculated, allowing the Gibbs free energy of the solid solution to be derived using the Debye–Wang model. On the basis of this new theoretical insights, a thermodynamic model was developed, predicting the Si occupancy factors in all the mixed sites of the structure at different temperatures, allowing the quantification of its chemical ordering.

Uncontrolled Keywords

τ8-Al₂Fe₃Si₄; crystal chemistry; first-principles calculations; debye model; short-range order

Subjects: 1800 Chemical engineering > 1800 Chemical engineering
Department: Department of Chemical Engineering
Research Center: CRCT - Centre for Research in Computational Thermochemistry
Funders: CRSNG/NSERC, Alliance Grant
Grant number: RGPIN-2017-06168, ALLRP 560998 - 20
PolyPublie URL: https://publications.polymtl.ca/57912/
Journal Title: Physica B: Condensed Matter (vol. 681)
Publisher: Elsevier
DOI: 10.1016/j.physb.2024.415834
Official URL: https://doi.org/10.1016/j.physb.2024.415834
Date Deposited: 03 Apr 2024 15:55
Last Modified: 15 Apr 2024 21:20
Cite in APA 7: Lafaye, P., Poëti, K., & Harvey, J.-P. (2024). Ab-initio calculations, Debye-Wang model and thermodynamic modeling for the short-range order and crystal chemistry characterisation of the τ8-Al₂Fe₃Si₄ solid solution. Physica B: Condensed Matter, 681, 415834 (7 pages). https://doi.org/10.1016/j.physb.2024.415834

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