Low-frequency conductivity of low wear high-entropy alloys

Abstract

High-entropy alloys (HEAs) provide new research avenues for alloy combinations in the periodic table, opening numerous possibilities in novel-alloy applications. However, their electrical characteristics have been relatively underexplored. The challenge in establishing an HEA electrical conductivity model lies in the changes in electronic characteristics caused by lattice distortion and complexity of nanostructures. Here we show a low-frequency electrical conductivity model for the Nb-Mo-Ta-W HEA system. The cocktail effect is found to explain trends in electrical-conductivity changes in HEAs, while the magnitude of the reduction is understood by the calculated plasma frequency, free electron density, and measured relaxation time by terahertz spectroscopy. As a result, the refractory HEA Nb ₁₅Mo ₃₅Ta ₁₅W ₃₅ thin film exhibits both high hardness and excellent conductivity. This combination of Nb ₁₅Mo ₃₅Ta ₁₅W ₃₅ makes it suitable for applications in atomic force microscopy probe coating, significantly improving their wear resistance and atomic-scale image resolution.

Abstract

The transport behavior of high-entropy alloys (HEAs) remains unclear. Here, the authors explore the fundamentals of low-wear and high-conductivity refractory HEAs, examining the cocktail effect in conductivity, and highlight its potential applications in enhancing atomic-scale image resolution.