期刊
ACTA MATERIALIA
卷 134, 期 -, 页码 334-345出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2017.05.001
关键词
Concentrated solid solution alloys; Stacking fault energy; First-principles calculations; Vibrational entropy
资金
- Energy Dissipation to Defect Evolution (EDDE), an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Basic Energy Sciences
We report the stacking fault energy (SFE) for a series of face-centered cubic (fcc) equiatomic concentrated solid solution alloys (CSAs) derived as subsystems from the NiCoFeCrMn and NiCoFeCrPd high entropy alloys based on ab initio calculations. At low temperatures, these CSAs display very low even negative SFEs, indicating that hexagonal close-pack (hcp) is more energy favorable than fcc structure. The temperature dependence of SFE for some CSAs is studied. With increasing temperature, a hcp-to-fcc transition is revealed for those CSAs with negative SFEs, which can be attributed to the role of intrinsic vibrational entropy. The analysis of the vibrational modes suggests that the vibrational entropy arises from the high frequency states in the hcp structure that originate from local vibrational mode. Our results underscore the importance of vibrational entropy in determining the temperature dependence of SFE for CSAs. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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