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DFT-CEF approach for the thermodynamic properties and volume of stable and metastable Al-Ni compounds

Tumminello, Silvana and Palumbo, M. and Koßmann, Jörg and Hammerschmidt, Thomas and Alonso, P.R. and Sommadossi, S. and Fries, S. G. (2020) DFT-CEF approach for the thermodynamic properties and volume of stable and metastable Al-Ni compounds. Metals. Multidisciplinary Digital Publishing Institute (MDPI). doi: 10.3390/met10091142. ISSN 2075-4701.

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The Al-Ni system has been intensively studied both experimentally and theoretically. The published 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 to predict the configurational contributions to the Gibbs energy. 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.

Item URL in elib:https://elib.dlr.de/137154/
Document Type:Article
Title:DFT-CEF approach for the thermodynamic properties and volume of stable and metastable Al-Ni compounds
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Tumminello, SilvanaGerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Palumbo, M.Universität Turin, ItalienUNSPECIFIED
Koßmann, JörgClouth Sprenger GmbH, Pferdsweide 47 (47441) Moers, GermanyUNSPECIFIED
Hammerschmidt, ThomasRuhr-Universität BochumUNSPECIFIED
Alonso, P.R.Instituto Sabato, Universidad Nacional de San Martín, Buenos Aires, Argentina and Gerencia de Materiales, Comisión Nacional de Energía Atómica, Buenos Aires, ArgentinaUNSPECIFIED
Sommadossi, S.Caracterización de Materiales, Universidad Nacional del Comahue / IITCI-CONICET, Neuquén, ArgentinaUNSPECIFIED
Fries, S. G.ICAMS, Ruhr University Bochum, Bochum, GermanyUNSPECIFIED
Date:24 August 2020
Journal or Publication Title:Metals
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.3390/met10091142
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
Keywords:DFT; Calphad; multiphase equilibria, thermodynamic properties
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Road Transport
DLR - Research area:Transport
DLR - Program:V ST Straßenverkehr
DLR - Research theme (Project):V - NGC Antriebssystem und Energiemanagement
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Frank, Adina
Deposited On:06 Nov 2020 10:23
Last Modified:06 Nov 2020 10:23

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