The Role of Allotropy on Phase Formation in High Entropy Alloys
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866914929408212992 |
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| author | Kaufmann, Kevin Wang, Haoren Saini, Jaskaran Vecchio, Kenneth S. |
| author_facet | Kaufmann, Kevin Wang, Haoren Saini, Jaskaran Vecchio, Kenneth S. |
| contents | Identifying single phase, high-entropy systems has been a prominent research focus of materials engineering over the past decade. The considerable effort in computational modeling and experimental verification has yielded several methods and descriptors for predicting if a single phase will form; however, the details surrounding the resulting crystal structure have largely remained a mystery. Here, we present a compelling argument for the role of allotropy in determining the crystal structure of a single-phase, high-entropy alloy. High entropy alloys can contain 5 or more elements and must achieve a configurational entropy greater than 1.5R. This study shows that when these high entropy material conditions are met, the majority crystal structure of the non-allotrope forming element plays a dominant role in crystal structure determination. The theory is demonstrated via several approaches, including analysis of 434 unique known single-phase compositions from the literature, thermodynamic modeling of more than 1,400 compositions, and experimental synthesis of nine specific alloys that test this hypothesis. The results demonstrate allotropy can identify a subset of compositions unlikely to form a single phase and predict the crystal structure with a high degree of accuracy for a wide range of simple (e.g., 5 equiatomic elements) and more complex (e.g., Al0.3B0.6CoCrFeNiCu0.7Si0.1) high entropy alloys. Allotropy provides new insight into the underlying physics governing the resultant crystal structure in materials without a principle element. As high entropy materials continue to be an area of focus for developing materials with unique properties, this study is expected to serve as a significant tool in the screening of materials for specific crystal structures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_16836 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The Role of Allotropy on Phase Formation in High Entropy Alloys Kaufmann, Kevin Wang, Haoren Saini, Jaskaran Vecchio, Kenneth S. Materials Science Identifying single phase, high-entropy systems has been a prominent research focus of materials engineering over the past decade. The considerable effort in computational modeling and experimental verification has yielded several methods and descriptors for predicting if a single phase will form; however, the details surrounding the resulting crystal structure have largely remained a mystery. Here, we present a compelling argument for the role of allotropy in determining the crystal structure of a single-phase, high-entropy alloy. High entropy alloys can contain 5 or more elements and must achieve a configurational entropy greater than 1.5R. This study shows that when these high entropy material conditions are met, the majority crystal structure of the non-allotrope forming element plays a dominant role in crystal structure determination. The theory is demonstrated via several approaches, including analysis of 434 unique known single-phase compositions from the literature, thermodynamic modeling of more than 1,400 compositions, and experimental synthesis of nine specific alloys that test this hypothesis. The results demonstrate allotropy can identify a subset of compositions unlikely to form a single phase and predict the crystal structure with a high degree of accuracy for a wide range of simple (e.g., 5 equiatomic elements) and more complex (e.g., Al0.3B0.6CoCrFeNiCu0.7Si0.1) high entropy alloys. Allotropy provides new insight into the underlying physics governing the resultant crystal structure in materials without a principle element. As high entropy materials continue to be an area of focus for developing materials with unique properties, this study is expected to serve as a significant tool in the screening of materials for specific crystal structures. |
| title | The Role of Allotropy on Phase Formation in High Entropy Alloys |
| topic | Materials Science |
| url | https://arxiv.org/abs/2408.16836 |