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The Effect of Scandium Ternary Intergrain Precipitates in Al-Containing High-Entropy Alloys
Sephira Riva,
Shahin Mehraban,
Nicholas Lavery 
,
Stefan Schwarzmüller,
Oliver Oeckler,
Stephen Brown,
Kirill Yusenko,
Steve Brown
,
Stefan Schwarzmüller,
Oliver Oeckler,
Stephen Brown,
Kirill Yusenko,
Steve Brown
Entropy, Volume: 20, Issue: 7, Start page: 488
Swansea University Authors:
Nicholas Lavery , Steve Brown
-
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DOI (Published version): 10.3390/e20070488
Abstract
We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al2CoCrFeNi, Al0.5CoCrCuFeNi, and AlCoCrCu0.5FeNi high-entropy alloys. Out of the three model alloys, Al2CoCrFeNi adopts a disordered CsCl str...
| Published in: | Entropy |
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| ISSN: | 1099-4300 |
| Published: |
2018
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa40823 |
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| Abstract: |
We investigate the effect of alloying with scandium on microstructure, high-temperature phase stability, electron transport, and mechanical properties of the Al2CoCrFeNi, Al0.5CoCrCuFeNi, and AlCoCrCu0.5FeNi high-entropy alloys. Out of the three model alloys, Al2CoCrFeNi adopts a disordered CsCl structure type. Both of the six-component alloys contain a mixture of body-centered cubic (bcc) and face centered cubic (fcc) phases. The comparison between in situ high-temperature powder diffraction data and ex situ data from heat-treated samples highlights the presence of a reversible bcc to fcc transition. The precipitation of a MgZn2-type intermetallic phase along grain boundaries following scandium addition affects all systems differently, but especially enhances the properties of Al2CoCrFeNi. It causes grain refinement; hardness and electrical conductivity increases (up to 20% and 14% respectively) and affects the CsCl-type → fcc equilibrium by moving the transformation to sensibly higher temperatures. The maximum dimensionless thermoelectric figure of merit (ZT) of 0.014 is reached for Al2CoCrFeNi alloyed with 0.3 wt.% Sc at 650 °C. |
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| Keywords: |
high-entropy alloys; in situ X-ray diffraction; grain refinement; thermoelectric properties; scandium effect |
| College: |
Faculty of Science and Engineering |
| Issue: |
7 |
| Start Page: |
488 |