1. Introducing a new heterogeneous nanocomposite thin film with superior mechanical properties and thermal stability.
- Author
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Zhao, Hong, Zheng, Zhong, Sun, Lixian, Liu, Hongwei, Tsoutas, Kostadinos, Akhavan, Behnam, Liu, Yanping, Bilek, Marcela M., and Liu, Zongwen
- Subjects
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THIN films , *THERMAL stability , *THERMAL properties , *FACE centered cubic structure , *THERMAL instability - Abstract
[Display omitted] • The as-deposited AlCrFeCoNiCu 0.5 films were annealed at 500 °C for up to 72 h. • Four new phases were formed during the 72 h of annealing. • The formation of a new heterogeneous nanocomposite thin film was revealed. • A 30% enhancement of mechanical properties was achieved after 72 h annealing. • The as-annealed thin films exhibited superior thermal stability. High entropy alloy (HEA) films offer excellent mechanical properties due to their random solid solution structure. However, their large grain boundary volume fraction can cause thermal instability, resulting in phase decomposition that affects their high-temperature performance. Nevertheless, it remains an interesting question whether phase decomposition can be used as a processing tool to create new HEA materials. In this study, AlCrFeCoNiCu0.5 HEA thin films were fabricated and annealed at 500 °C for up to 72 h. The 72-hour annealed thin film exhibited a 30 % increase in mechanical properties, exceeding most other HEA thin films. Characterization using X-ray and electron microscopy revealed a decomposition-induced phase transformation, which produced four new phases, including Cu-rich FCC phase, Cr-rich BCC phase, and ordered B2 phase of AlNi and FeCo. The enhanced mechanical properties were due to back stress strengthening and BCC + B2 phase strengthening. The 72-hour annealed thin film also showed excellent thermal stability through a new round of annealing, exhibiting a low variation in microstructure and chemical composition after being annealed at 500 °C for 100 h. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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