Journal
INTERMETALLICS
Volume 149, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.intermet.2022.107655
Keywords
High-entropy alloy; L1(2) precipitate; Continuous precipitation; Discontinuous precipitation; Temperature effect
Categories
Funding
- National Natural Science Foundation of China [52171162, 51801169]
- Research Grants Council of Hong Kong [ECS 25202719, GRF 15227121, ECS 21205621, C1020-21 GF, C1017-21 GF]
- Shenzhen Science and Technology Program [JCYJ20210324142203009]
- State Key Laboratory for Advanced Metals and Materials Open Fund [2021-ZD04]
- Research Institute for Advanced Manufacturing at PolyU [P0041364]
- Guangdong Basic and Applied Basic Reuter Foundation [2020A1515110647]
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This study systematically investigates the effects of aging temperature, aging time, and grain size on the CP and DP behaviors of L1(2)-strengthened HEAs. The results show that low temperatures favor the DP reaction, while high temperatures facilitate the CP reaction. At intermediate temperatures, both the CP and DP occur simultaneously and compete with each other. Grain size refinement can promote the DP reaction and result in a DP-dominant microstructure.
Understanding of the competition between continuous precipitation (CP) and discontinuous precipitation (DP) is crucial for tailoring the microstructure and mechanical properties of precipitation-strengthened high-entropy alloys (HEAs). In this study, the effects of aging temperature, aging time, and grain size on the CP and DP be-haviors of L1(2)-strengthened HEAs were systematically investigated. Our results reveal that low temperatures favor the DP reaction while high temperatures facilitate the CP reaction, which is related to the nucleation site and diffusion path of the two precipitation modes. At intermediate temperatures, both the CP and DP occur simultaneously and compete with each other, and the solute concentration difference across the boundaries between the two precipitation regions serves as the driving force for the sweeping of the CP regions by the DP reaction. In addition, grain size refinement can promote the DP reaction by providing more nucleation sites and more fast diffusion paths, leading to the formation of the DP-dominant microstructure. This study not only sheds light on the fundamental understanding of the CP and DP mechanisms but also provides useful guidelines for the microstructure design of advanced L1(2)-strengthened HEAs.
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