The Effect of Scandium on the Structure, Microstructure and Superconductivity of Equimolar Sc-Hf-Nb-Ta-Ti-Zr Refractory High-Entropy Alloys
Journal article, 2022

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.

High-entropy alloys

Structure and microstructure



Mitja Krnel

Jozef Stefan Institute

A. Jelen

Jozef Stefan Institute

S. Vrtnik

Jozef Stefan Institute

J. Luzar

Jozef Stefan Institute

Darja Gačnik

Jozef Stefan Institute

P. Koželj

Jozef Stefan Institute

University of Ljubljana

Magdalena Wencka

Polish Academy of Sciences

Jozef Stefan Institute

A. Meden

University of Ljubljana

Q. Hu

Jiangxi Academy of Sciences

Sheng Guo

Chalmers, Industrial and Materials Science, Materials and manufacture

J. Dolinšek

University of Ljubljana

Jozef Stefan Institute


1996-1944 (ISSN)

Vol. 15 3 1122

Subject Categories

Physical Chemistry

Materials Chemistry

Metallurgy and Metallic Materials





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