Thermal Stability of Microstructure of High-Entropy Alloys Based on Refractory Metals Hf, Nb, Ta, Ti, V, and Zr

0558570 - ÚFP 2023 RIV CH eng J - Journal Article
Vlasák, T. - Čížek, J. - Melikhova, O. - Lukáč, František - Preisler, D. - Janeček, M. - Harcuba, P. - Zimina, M. - Srba, O.
Thermal Stability of Microstructure of High-Entropy Alloys Based on Refractory Metals Hf, Nb, Ta, Ti, V, and Zr.
Metals. Roč. 12, č. 3 (2022), č. článku 394. E-ISSN 2075-4701
Institutional support: RVO:61389021
Keywords : High-entropy alloys * Refractory metals * Solid solution
OECD category: Materials engineering
Impact factor: 2.9, year: 2022
Method of publishing: Open access
https://www.mdpi.com/2075-4701/12/3/394

In the present work, a series of high-entropy alloys based on refractory metals Hf, Nb, Ta, Ti, V, and Zr with various compositions have been systematically investigated. Our study revealed that a bcc single-phase solid solution of a Hf-Nb-Ta-Ti-V-Zr system is thermodynamically stable only at high temperatures above 1000◦ C. At lower temperatures, the phase separation into disordered bcc phases with slightly different chemical compositions occurs. Despite the phase separation, a single-phase random solid solution can be saved at room temperature as a metastable phase by rapid cooling of the sample from high temperature. The microstructure of a single-phase metastable random solid solution was characterized and compared with the microstructure of the as-cast state. Furthermore, the mechanical properties of annealed and as-cast alloys were compared. Interestingly, both states exhibit comparable mechanical properties. It indicates that from the point of view of practical applications, a mechanical mixture of disordered bcc solutions is as good as single-phase random solid solution.
Permanent Link: http://hdl.handle.net/11104/0332210