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Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range

We determined the entropy of high entropy alloys by investigating single-crystalline nickel and five high entropy alloys: two fcc-alloys, two bcc-alloys and one hcp-alloy. Since the configurational entropy of these single-phase alloys differs from alloys using a base element, it is important to quan...

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Autores principales: Haas, Sebastian, Mosbacher, Mike, Senkov, Oleg N., Feuerbacher, Michael, Freudenberger, Jens, Gezgin, Senol, Völkl, Rainer, Glatzel, Uwe
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7513177/
https://www.ncbi.nlm.nih.gov/pubmed/33265743
http://dx.doi.org/10.3390/e20090654
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author Haas, Sebastian
Mosbacher, Mike
Senkov, Oleg N.
Feuerbacher, Michael
Freudenberger, Jens
Gezgin, Senol
Völkl, Rainer
Glatzel, Uwe
author_facet Haas, Sebastian
Mosbacher, Mike
Senkov, Oleg N.
Feuerbacher, Michael
Freudenberger, Jens
Gezgin, Senol
Völkl, Rainer
Glatzel, Uwe
author_sort Haas, Sebastian
collection PubMed
description We determined the entropy of high entropy alloys by investigating single-crystalline nickel and five high entropy alloys: two fcc-alloys, two bcc-alloys and one hcp-alloy. Since the configurational entropy of these single-phase alloys differs from alloys using a base element, it is important to quantify the entropy. Using differential scanning calorimetry, c(p)-measurements are carried out from −170 °C to the materials’ solidus temperatures T(S). From these experiments, we determined the thermal entropy and compared it to the configurational entropy for each of the studied alloys. We applied the rule of mixture to predict molar heat capacities of the alloys at room temperature, which were in good agreement with the Dulong-Petit law. The molar heat capacity of the studied alloys was about three times the universal gas constant, hence the thermal entropy was the major contribution to total entropy. The configurational entropy, due to the chemical composition and number of components, contributes less on the absolute scale. Thermal entropy has approximately equal values for all alloys tested by DSC, while the crystal structure shows a small effect in their order. Finally, the contributions of entropy and enthalpy to the Gibbs free energy was calculated and examined and it was found that the stabilization of the solid solution phase in high entropy alloys was mostly caused by increased configurational entropy.
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spelling pubmed-75131772020-11-09 Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range Haas, Sebastian Mosbacher, Mike Senkov, Oleg N. Feuerbacher, Michael Freudenberger, Jens Gezgin, Senol Völkl, Rainer Glatzel, Uwe Entropy (Basel) Article We determined the entropy of high entropy alloys by investigating single-crystalline nickel and five high entropy alloys: two fcc-alloys, two bcc-alloys and one hcp-alloy. Since the configurational entropy of these single-phase alloys differs from alloys using a base element, it is important to quantify the entropy. Using differential scanning calorimetry, c(p)-measurements are carried out from −170 °C to the materials’ solidus temperatures T(S). From these experiments, we determined the thermal entropy and compared it to the configurational entropy for each of the studied alloys. We applied the rule of mixture to predict molar heat capacities of the alloys at room temperature, which were in good agreement with the Dulong-Petit law. The molar heat capacity of the studied alloys was about three times the universal gas constant, hence the thermal entropy was the major contribution to total entropy. The configurational entropy, due to the chemical composition and number of components, contributes less on the absolute scale. Thermal entropy has approximately equal values for all alloys tested by DSC, while the crystal structure shows a small effect in their order. Finally, the contributions of entropy and enthalpy to the Gibbs free energy was calculated and examined and it was found that the stabilization of the solid solution phase in high entropy alloys was mostly caused by increased configurational entropy. MDPI 2018-08-30 /pmc/articles/PMC7513177/ /pubmed/33265743 http://dx.doi.org/10.3390/e20090654 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Haas, Sebastian
Mosbacher, Mike
Senkov, Oleg N.
Feuerbacher, Michael
Freudenberger, Jens
Gezgin, Senol
Völkl, Rainer
Glatzel, Uwe
Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title_full Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title_fullStr Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title_full_unstemmed Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title_short Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range
title_sort entropy determination of single-phase high entropy alloys with different crystal structures over a wide temperature range
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7513177/
https://www.ncbi.nlm.nih.gov/pubmed/33265743
http://dx.doi.org/10.3390/e20090654
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