Insight into high-entropy effect in body-centered cubic superconducting alloys

Abstract

We have characterized the superconducting critical temperature ($T_{\mathrm{c}}$), the Debye temperature (${\theta }_{\mathrm{D}}$), the electronic specific heat coefficient, and the Vickers microhardness of HfNbTiVZr, NbTiZr, HfNbTi, HfNbZr, and HfNbTa, all possessing a body-centered cubic (bcc) structure. By compiling a comparable dataset for other equiatomic quinary bcc high-entropy alloy (HEA) superconductors, we have examined the validity of the hypothesis regarding the high-entropy effect in bcc HEA superconductors, as proposed in our previous work. This hypothesis attributes the observed negative correlation between the electron-phonon coupling constant (${\lambda }_{\mathrm{e}-\mathrm{p}}$) and ${\theta }_{\mathrm{D}}$ to a reduced phonon lifetime at higher ${\theta }_{\mathrm{D}}$, arising from the uncertainty principle in highly disordered quinary alloys. However, a pronounced change in this negative correlation is not evident in equiatomic ternary alloys with a lower degree of atomic disorder, thereby providing limited support for the hypothesis. Alternatively, by assembling the full dataset of bcc alloys spanning binary through senary systems, we have identified a universal negative correlation between ${\lambda }_{\mathrm{e}-\mathrm{p}}$ and ${\theta }_D$. This result would be useful for the materials design of bcc superconducting alloys. We further propose that the Vickers microhardness offers an alternative means to evaluate ${\theta }_D$ and may serve as a rapid screening metric for identifying bcc alloys with desired properties.

References in corpus (6)

• Effect of Electron Count and Chemical Complexity in the Ta-Nb-Hf-Zr-Ti High-Entropy Alloy Superconductor
• Isoelectronic Substitutions and Aluminium Alloying in the Ta-Nb-Hf-Zr-Ti High-Entropy Alloy Superconductor
• Fishtail effect and the vortex phase diagram of high-entropy alloy superconductor
• Superconductivity of Ta-Hf and Ta-Zr alloys: Potential alloys for use in superconducting devices
• Superconductivity with high upper critical field in Ta-Hf Alloys
• Enhanced $T_{\mathrm{c}}$ in eutectic high-entropy alloy superconductors Hf-Nb-Sc-Ti-Zr