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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MDPI AG
2018-08-01
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| Series: | Entropy |
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| Online Access: | http://www.mdpi.com/1099-4300/20/9/654 |
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| author | Sebastian Haas Mike Mosbacher Oleg N. Senkov Michael Feuerbacher Jens Freudenberger Senol Gezgin Rainer Völkl Uwe Glatzel |
| author_facet | Sebastian Haas Mike Mosbacher Oleg N. Senkov Michael Feuerbacher Jens Freudenberger Senol Gezgin Rainer Völkl Uwe Glatzel |
| author_sort | Sebastian Haas |
| collection | DOAJ |
| 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, cp-measurements are carried out from −170 °C to the materials’ solidus temperatures TS. 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. |
| first_indexed | 2024-12-10T08:16:14Z |
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| id | doaj.art-980ac8d1a11c45d6b8fe00869e7c67aa |
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| issn | 1099-4300 |
| language | English |
| last_indexed | 2024-12-10T08:16:14Z |
| publishDate | 2018-08-01 |
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| spelling | doaj.art-980ac8d1a11c45d6b8fe00869e7c67aa2022-12-22T01:56:27ZengMDPI AGEntropy1099-43002018-08-0120965410.3390/e20090654e20090654Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature RangeSebastian Haas0Mike Mosbacher1Oleg N. Senkov2Michael Feuerbacher3Jens Freudenberger4Senol Gezgin5Rainer Völkl6Uwe Glatzel7Metals and Alloys, University Bayreuth, 95447 Bayreuth, GermanyMetals and Alloys, University Bayreuth, 95447 Bayreuth, GermanyUES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432, USAInstitut für Mikrostrukturforschung, Forschungszentrum Jülich, 52425 Jülich, GermanyLeibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), 01069 Dresden, GermanyNETZSCH Group, Analyzing & Testing, 95100 Selb, GermanyMetals and Alloys, University Bayreuth, 95447 Bayreuth, GermanyMetals and Alloys, University Bayreuth, 95447 Bayreuth, GermanyWe 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, cp-measurements are carried out from −170 °C to the materials’ solidus temperatures TS. 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.http://www.mdpi.com/1099-4300/20/9/654HEAentropymulticomponentdifferential scanning calorimetry (DSC)specific heat |
| spellingShingle | Sebastian Haas Mike Mosbacher Oleg N. Senkov Michael Feuerbacher Jens Freudenberger Senol Gezgin Rainer Völkl Uwe Glatzel Entropy Determination of Single-Phase High Entropy Alloys with Different Crystal Structures over a Wide Temperature Range Entropy HEA entropy multicomponent differential scanning calorimetry (DSC) specific heat |
| 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 | HEA entropy multicomponent differential scanning calorimetry (DSC) specific heat |
| url | http://www.mdpi.com/1099-4300/20/9/654 |
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