Abstract
Niobium (Nb) presents a challenge for achieving homogeneous solid solutions in high-entropy boride and carbide ceramics. In this work, we synthesized (Hf,Ta,Ti,Zr)B2 (Zr-HEB) and (Hf,Ta,Ti,Nb)B2 (Nb-HEB) ceramics by boro/carbothermal reduction, followed by densification via spark plasma sintering (SPS). Diffusion couples were prepared to investigate the interdiffusion behavior of Nb and zirconium (Zr) in these complex systems at temperatures between 2000°C and 2200°C. Aside from Nb and Zr, the other elements exhibited no significant concentration gradient across the diffusion interface. Nb exhibited lower diffusion coefficients ((Formula presented.) Nb = 1.7 x 10−17–1.2 x 10−16 m2/s) compared to Zr ((Formula presented.) Zr = 1.9 x 10−17–1.7 x 10−16 m2/s) over the temperature range of 2000°C–2200°C. However, at 2200°C, their interdiffusion coefficients were comparable. The calculated activation energy for diffusion of Nb into Zr-HEB (QNb = 1008 ± 76 kJ/mol) was nearly twice that of Zr into Nb-HEB (QZr = 565 ± 54 kJ/mol). The slower diffusion of Nb is derived from the electronegativity difference between Nb and boron (B) and the bonding characteristics of NbB2 compared to the other diborides.
Recommended Citation
A. C. Feltrin et al., "Nb–Zr Interdiffusion In The (Hf,Ta,Ti,Nb)B2–(Hf,Ta,Ti,Zr)B2 High-Entropy Boride System," Journal of the American Ceramic Society, vol. 109, no. 7, article no. e70958, Wiley, Jul 2026.
The definitive version is available at https://doi.org/10.1111/jace.70958
Department(s)
Materials Science and Engineering
Publication Status
Full Access
Keywords and Phrases
diffusion couple; interdiffusion; Kirkendall effect; niobium; zirconium
International Standard Serial Number (ISSN)
1551-2916; 0002-7820
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2026 Wiley, All rights reserved.
Publication Date
01 Jul 2026
Comments
Office of Naval Research, Grant N00014–21–1–2515