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Thermodynamic Modelling of Hydrogen-Multicomponent Alloy Systems: Calculating Pressure-Composition-Temperature Diagrams

preprint
submitted on 21.04.2021, 11:46 and posted on 22.04.2021, 10:08 by Guilherme Zepon, Bruno Silva, Claudia Zlotea, Walter José Botta, Yannick Champion

The applicability of an alloy as a hydrogen storage media mostly relies on its pressure-composition-temperature (PCT) diagram. Since the PCT diagram is composition-dependent, the vast compositional filed of high entropy alloys, complex concentrated alloys or multicomponent alloys can be explored to design alloys with optimized properties for each application. In this work, we present a thermodynamic model to calculate PCT diagrams of body-centered (BCC) multicomponent alloys. The entropy of the phases is described using the ideal configurational entropy for interstitial solid solutions with site blocking effect. As a first approximation, it is assumed that the H partial molar enthalpy of a phase is constant, so the enthalpy of H mixing varies linearly with the H concentration. Moreover, the H partial enthalpy of a phase for a multicomponent alloy was approximated by a simple ideal mixture law of this quantity for the alloy’s components with the same structure. Experimental data and DFT calculations were used for parametrization of the enthalpy terms of eight elements (Ti, V, Cr, Ni, Zr, Nb, Hf, and Ta), which are the components of the alloys tested in this work. Experimental PCTs of six BCC multicomponent alloys of four different systems were compared against the calculated ones and the agreement was remarkable. The model and parameters presented here can be regarded as a basis for developing powerful alloy design tools for different hydrogen storage applications.

Funding

Serrapilheira Institute (grant number Serra-1709-17362)

CAPES-COFECUB (CAPES project numbers: 88887.387428/2019-00 and 88887.191910/2018-00, COFECUB project number: Ph-C951/19)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001

History

Email Address of Submitting Author

zepon@ufscar.br

Institution

Federal University of São Carlos, Department of Materials Engineering

Country

Brazil

ORCID For Submitting Author

0000-0002-5852-9076

Declaration of Conflict of Interest

No conflict of interest

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