The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys

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

doi:10.3390/ma15031122

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The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys

¹,

¹,

^1,2

^1,3,

⁴,

^5,*,

⁶

and

Janez Dolinšek

^1,2,*

Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia

Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia

Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, PL-60-179 Poznań, Poland

⁴

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia

⁵

Institute of Applied Physics, Jiangxi Academy of Sciences, Changdong Road 7777, Nanchang 330096, China

⁶

Industrial and Materials Science, Chalmers University of Technology, SE-41296 Göteborg, Sweden

Authors to whom correspondence should be addressed.

Materials 2022, 15(3), 1122; https://doi.org/10.3390/ma15031122

Received: 24 December 2021 / Revised: 24 January 2022 / Accepted: 28 January 2022 / Published: 31 January 2022

(This article belongs to the Section Metals and Alloys)

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Abstract

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. View Full-Text

Keywords: high-entropy alloys; structure and microstructure; superconductivity

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MDPI and ACS Style

Krnel, M.; Jelen, A.; Vrtnik, S.; Luzar, J.; Gačnik, D.; Koželj, P.; Wencka, M.; Meden, A.; Hu, Q.; Guo, S.; Dolinšek, J. The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys. Materials 2022, 15, 1122. https://doi.org/10.3390/ma15031122

AMA Style

Krnel M, Jelen A, Vrtnik S, Luzar J, Gačnik D, Koželj P, Wencka M, Meden A, Hu Q, Guo S, Dolinšek J. The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys. Materials. 2022; 15(3):1122. https://doi.org/10.3390/ma15031122

Chicago/Turabian Style

Krnel, Mitja, Andreja Jelen, Stanislav Vrtnik, Jože Luzar, Darja Gačnik, Primož Koželj, Magdalena Wencka, Anton Meden, Qiang Hu, Sheng Guo, and Janez Dolinšek. 2022. "The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys" Materials 15, no. 3: 1122. https://doi.org/10.3390/ma15031122

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The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys

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