About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
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Symposium
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Advances in Multi-Principal Element Alloys III: Mechanical Behavior
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Presentation Title |
Absence of Equilibrium B2 Phase in Three Al-Nb-Ta-Ti- Zr Refractory High-entropy Alloys Above 700°C |
Author(s) |
An-Chen Fan, Yun-Syuan Chen, Chong-Chi Chi, Daniel B. Miracle, Chih-Hao Hsu, Kai-Cheng Yang, Shu-Yi Tung, Ming-Yen Lu, Ming-Hung Tsai |
On-Site Speaker (Planned) |
Ming-Hung Tsai |
Abstract Scope |
Refractory high-entropy superalloys (RHESAs), or RHEAs with superalloy-like BCC+B2 microstructure, can exhibit superior strength at elevated temperatures compared to single-phased BCC RHEAs. However, the understanding of the equilibrium conditions of the B2 phase in RHEAs remains elusive. Here, three alloys potentially containing the B2 phase in the Al-Nb-Ta-Ti-Zr system were chosen to investigate the equilibrium phase constituents, microstructures, and phase compositions at different temperatures. Surprisingly, we discover nanoscale interconnected BCC+B2 structures in the macroscopic “B2” phases in these alloys. Our analysis reveals that the B2 phases within the interconnected structures are formed during quenching via spinodal decomposition, indicating the absence of equilibrium B2 phase in the alloys above 700°C. In fact, the accurate identification of the B2 phase is further complicated by an (Al,Zr)-rich intermetallic phase, which can easily be misidentified as the B2 phase. Challenges associated with correctly identifying the equilibrium B2 phase in these materials are also discussed. |
Proceedings Inclusion? |
Planned: |
Keywords |
High-Entropy Alloys, Characterization, High-Temperature Materials |