The effect of scandium on the structure, microstructure and superconductivity of equimolar Sc-Hf-Nb-Ta-Ti-Zr refractory high-entropy alloys

Krnel, Mitja (author), Jelen, Andreja (author), Vrtnik, Stanislav (author), Luzar, Jože (author), Gačnik, Darja (author), Koželj, Primož (author), Wencka, Magdalena (author), Meden, Anton (author), Hu, Qiang (author), Guo, Sheng (author), Dolinšek, Janez (author)

In this study, we investigate the scandium-containing Sc-Hf-Nb-Ta-Ti-Zr system of refractory high-entropy alloys (HEAs). Using the arc-melting method, we synthesized nine equimolar alloys (five 4-, three 5- and one 6-component), with all of them containing Sc. The alloys were characterized by XRD, electron microscopy and EDS, while superconductivity was investigated via electrical resistivity, specific heat and the Meissner effect. The results were compared to the parent Hf-Nb-Ta-Ti-Zr refractory HEAs, forming a single-phase body-centered cubic (bcc) structure and quite homogeneous microstructure. The addition of Sc produces a two-phase structure in the Sc-Hf-Nb-Ta-Ti-Zr alloys, with one phase being bcc and the other hexagonal close-packed (hcp). The hcp phase absorbs practically all Sc, whereas the Sc-poor bcc phase is identical to the bcc phase in the Hf-Nb-Ta-Ti-Zr parent system. Upon the Sc addition, the microstructure becomes very inhomogeneous. Large bcc dendrites (10–100 µm) are homogeneous in the central parts, but become a fine dispersion of sub-micron precipitates of the bcc and hcp phases close to the edges. The interdendritic regions are also a fine dispersion of the two phases. Superconductivity of the Sc-Hf-Nb-Ta-Ti-Zr alloys originates from the bcc phase fraction, which demonstrates identical superconducting parameters as the bcc Hf-Nb-Ta-Ti-Zr parent alloys, while the Sc-containing hcp phase fraction is non-superconducting.

• Language: English
• Keywords: high-entropy alloys, structure and microstructure, superconductivity
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics; FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 20 str.
• Numbering: Vol. 15, iss. 3, art. 1122
• PID: 20.500.12556/RUL-136988
• UDC: 53
• ISSN on article: 1996-1944
• DOI: 10.3390/ma15031122
• COBISS.SI-ID: 95789315
• Publication date in RUL: 27.05.2022

Record is a part of a journal

• Title: Materials
• Shortened title: Materials
• Publisher: MDPI
• ISSN: 1996-1944
• COBISS.SI-ID: 33588485

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 01.02.2022

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0125
• Name: Magnetna resonanca in dielektrična spektroskopija pametnih novih materialov

• Funder: Other - Other funder or multiple funders
• Funding programme: National Science Foundation of China
• Project number: 52061016