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Open AccessArticle

DFT-CEF Approach for the Thermodynamic Properties and Volume of Stable and Metastable Al–Ni Compounds

1
ICAMS, Ruhr Universität Bochum, 44801 Bochum, Germany
2
Caracterización de Materiales, Universidad Nacional del Comahue/IITCI-CONICET, 8300 Neuquén, Argentina
3
Instituto Sabato, Universidad Nacional de San Martín, 1499 Buenos Aires, Argentina
4
Gerencia de Materiales, Comisión Nacional de Energía Atómica, 1499 Buenos Aires, Argentina
*
Author to whom correspondence should be addressed.
Current address: Institute of Materials Research, German Aerospace Center (DLR), 51147 Cologne, Germany.
Current address: Dipartimento di Chimica, Università di Torino, 10125 Torino, Italy.
§
Current address: Clouth Sprenger GmbH, Pferdsweide 47, 47441 Moers, Germany.
Metals 2020, 10(9), 1142; https://doi.org/10.3390/met10091142
Received: 23 July 2020 / Revised: 18 August 2020 / Accepted: 19 August 2020 / Published: 24 August 2020
The Al–Ni system has been intensively studied both experimentally and theoretically. Previous first-principles calculations based on density-functional theory (DFT) typically investigate the stable phases of this system in their experimental stoichiometry. In this work, we present DFT calculations for the Al–Ni system that cover stable and metastable phases across the whole composition range for each phase. The considered metastable phases are relevant for applications as they are observed in engineering alloys based on Al–Ni. To model the Gibbs energies of solid phases of the Al–Ni system, we combine our DFT calculations with the compound energy formalism (CEF) that takes the Bragg–Williams–Gorsky approximation for the configurational entropy. Our results indicate that the majority of the investigated configurations have negative energy of formation with respect to Al fcc and Ni fcc. The calculated molar volumes for all investigated phases show negative deviations from Zen’s law. The thermodynamic properties at finite temperatures of individual phases allow one to predict the configurational contributions to the Gibbs energy. By applying a fully predictive approach without excess parameters, an acceptable topology of the DFT-based equilibrium phase diagram is obtained at low and intermediate temperatures. Further contributions can be added to improve the predictability of the method, such as phonons or going beyond the Bragg–Williams–Gorsky approximation that overestimates the stability range of the ordered phases. This is clearly demonstrated in the fcc order/disorder predicted metastable phase diagram. View Full-Text
Keywords: DFT; Calphad; multiphase equilibria; thermodynamic properties DFT; Calphad; multiphase equilibria; thermodynamic properties
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MDPI and ACS Style

Tumminello, S.; Palumbo, M.; Koßmann, J.; Hammerschmidt, T.; Alonso, P.R.; Sommadossi, S.; Fries, S.G. DFT-CEF Approach for the Thermodynamic Properties and Volume of Stable and Metastable Al–Ni Compounds. Metals 2020, 10, 1142.

AMA Style

Tumminello S, Palumbo M, Koßmann J, Hammerschmidt T, Alonso PR, Sommadossi S, Fries SG. DFT-CEF Approach for the Thermodynamic Properties and Volume of Stable and Metastable Al–Ni Compounds. Metals. 2020; 10(9):1142.

Chicago/Turabian Style

Tumminello, Silvana; Palumbo, Mauro; Koßmann, Jörg; Hammerschmidt, Thomas; Alonso, Paula R.; Sommadossi, Silvana; Fries, Suzana G. 2020. "DFT-CEF Approach for the Thermodynamic Properties and Volume of Stable and Metastable Al–Ni Compounds" Metals 10, no. 9: 1142.

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