Origins of the transformability of nickel-titanium shape memory alloys
| Autor: | Yintao Song, Richard D. James, Xian Chen, Colin Ophus, Vikram Gavini, Jim Ciston, Andrew M. Minor, Sambit Das, Chengyu Song, Yuriy Chumlyakov |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Physics and Astronomy (miscellaneous) 02 engineering and technology Shape-memory alloy 021001 nanoscience & nanotechnology 01 natural sciences Engineering physics Niti alloy Transformation (function) Nickel titanium Diffusionless transformation 0103 physical sciences General Materials Science Involution (philosophy) 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review Materials. 4 |
| ISSN: | 2475-9953 |
| Popis: | The near equiatomic NiTi alloy is the most successful shape memory alloy by a large margin. It is widely and increasingly used in biomedical devices. Yet, despite having a repeatable superelastic effect and excellent shape-memory, NiTi is very far from satisfying the conditions that characterize the most reversible phase-transforming materials. Thus, the scientific reasons underlying its vast success present an enigma. In this paper, we perform rigorous mathematical derivations and accurate density-functional theory calculations of transformation mechanisms to seek previously unrecognized twinlike defects that we term involution domains, and we observe them in real space in NiTi by aberration-corrected scanning transmission electron microscopy. Involution domains lead to an additional 216 compatible interfaces between phases in NiTi, and we theorize that this feature contributes importantly to its reliability. They are expected to arise in other transformations and to alter the conventional interpretation of the mechanism of the martensitic transformation. |
| Databáze: | OpenAIRE |
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