Abstract
Equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. In order to understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased due to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. The temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.
Highlights
A new family of compositionally complex but structurally simple alloys, such as high-entropy alloys (HEA), has been successfully fabricated, in which the atomic fraction of each component is equal or near-equal[1,2,3,4,5,6,7]
Ab initio approaches applied in concentrated random solid solution alloys have been developed in the 1980’s, in which the coherent-potential approximation (CPA), an effective medium theory, is used to describe the effects of compositional disorder on the underlying electronic structure
The temperature dependence of the electrical resistivity varies in different temperature regimes
Summary
A new family of compositionally complex (containing 4, 5, or more elements) but structurally simple (e.g. face center cubic - FCC structured) alloys, such as high-entropy alloys (HEA), has been successfully fabricated, in which the atomic fraction of each component is equal or near-equal[1,2,3,4,5,6,7]. The CPA calculations have been successfully expanded to the applications in high entropy alloys, with majority of them focused on the structural, mechanical, defect, and magnetic properties[25,26,27,28,29,30]. In the case of physical properties, the general picture of the effects of chemical complexity on magnetism and electrical and thermal transport, especially at low temperatures, is still unclear in this new family of alloys. These alloys are selected in part because recent experiments confirmed that these equiatomic alloys form a single-phase solid-solution with the simple FCC crystal structure[32,34] These alloys provide an ideal system to systematically study how the type and number of elements affect the transport properties of equiatomic alloys. Magnetization data are reported for the five alloys with three or more elements from 4 to 300 K using applied fields between 0 and 4 Tesla
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