About this Abstract |
| Meeting |
11th International Symposium on Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
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| Symposium
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Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
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| Presentation Title |
Effect of Boron content on solidification behavior and microstructure of Nickel-Cobalt-Based superalloys |
| Author(s) |
Nan Jiang, Minqing Wang, Jinhui Du, Xiaopeng Xu, Sifan Yu |
| On-Site Speaker (Planned) |
Nan Jiang |
| Abstract Scope |
This study systematically investigates the effects of boron(B) content (0.02–0.2 wt.%) on the solidification microstructure, dendritic segregation, and phase transformation temperatures of nickel-cobalt-based superalloys. Experiments demonstrate that increasing B content significantly refines the dendritic structure, reducing the secondary dendrite average spacing (SDAS) from 46.6 μm (at 2/R) in low-B alloys to 34.8 μm in high-B alloys. This mechanism is primarily attributed to the strong composition undercooling effect caused by B enrichment at the solid-liquid interface. Regarding precipitated phases, B altered the phase composition within dendrites: the volume fraction of Laves phase increased significantly from 3.76% to 8.00% with increasing B content, transforming from isolated particles to a continuous network morphology. Concurrently, M3B2-type tetragonal borides rich in W and Cr precipitated extensively in high-B alloys. Conversely, precipitation of the β-NiAl phase is significantly suppressed. Elemental segregation analysis indicates that B intensifies segregation of refractory elements W and Ta, with the segregation coefficient KTa decreasing from 0.85 to 0.41, greatly promoting the formation of Ta-rich phases (Laves phases) during late solidification. Thermal analysis shows that B lowers the liquidus temperature and alters the final solidification path by forming low-melting-point eutectic liquid films. These results provide a theoretical basis for alloy design and casting control. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |