Microstructure and Superconductivity of Mechanically Alloyed Nb_0.67(TiZrHf)_0.33 High-Entropy Alloy

A superconducting high-entropy alloy (HEA) Nb_0.67(TiZrHf)_0.33 powder was successfully synthesized via mechanical alloying for the first time. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, magnetic measurements, and specific heat were used to investigate its structural and physical properties. The alloy was crystallized in a single-phase body-centered cubic structure with a small amount of non-magnetic impurities coming from ball milling. Specific heat data confirms the presence of bulk superconductivity in the as-synthesized state, with the broadness of the thermodynamic anomaly reflecting the significant chemical disorder and distribution of critical temperatures typical of HEAs. Tc is in the range 6-7.5 K, and the upper critical field μ0Hc2 is in the range 6.4-7.6 T. These results demonstrate that mechanical synthesis is a viable route for producing superconducting HEA powders, which are promising candidates for consolidation via sintering and provide a robust platform for investigating superconductivity in highly disordered systems.