Superior strain gauge sensitivity and elastic anisotropy in TiZrHfTa high entropy alloy

Abstract

A great research breakthrough that occurred in materials science twenty years ago has brought new metallurgical alloy design principles and made it possible to create a unique kind of artificial materials – multi-element concentrated alloys. These complex solid solutions reveal unique crystalline structures and promising physical and chemical properties. All of these alloys are interesting for their functionality, but they have not yet been introduced into daily life due to their high price and complexity of production. It has recently been proposed that electrical resistance strain gauges and pressure sensors are among the most suitable practical applications in which these materials can be efficiently implemented. The further development of such alloys requires an improved understanding of the physical mechanisms behind high strain gauge sensitivity in these systems. This study focuses on a comprehensive analysis of the effects of pressure and uniaxial stress on electrical resistivity in the equiatomic TiZrHfTa high-entropy alloy, which is a typical representative of this family of materials. We measure electrical, magnetic, and thermal properties of the system and calculate its electronic structure and elastic constants to address issues associated with the strain and pressure effects, as well as evaluate the overall functionality for this kind of alloys in terms of possible passive electronic sensors. The tested alloy exhibits virtually temperature-independent resistivity and a superior strain gauge factor as large as 5.17. By analyzing the obtained data, we suggest that elastic anisotropy effects play a key role in the strain-sensitive behavior of refractory high-entropy alloys.