Low-Frequency Conductivity of Low Wear High-Entropy Alloys

Abstract

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 and develops highly conductive and low wear HEA thin films. It is found that the compositional linear combinations, or the state-of-the-art cocktail effect, can be used to explain trends in electrical-conductivity changes in HEAs, but they cannot account for the magnitude of the reduction. We calculate the plasma frequency, free electron density, and measure the relaxation time using terahertz spectroscopy, resulting in a close match with experimental electrical conductivity trends and scales. This approach can be employed to predict the electrical conductivity of different HEAs for researchers. As a result, the refractory HEA Nb15Mo35Ta15W35 thin film exhibits both high hardness and excellent conductivity. This unique combination of Nb15Mo35Ta15W35 makes it suitable for applications in atomic force microscopy probe coating, significantly improving their wear resistance and atomic-scale image resolution.