Abstract
One of the intriguing recent results in the field of high-entropy alloys is the discovery of single-phase equiatomic multi-component Laves intermetallics. However, there is no clear understanding that a combination of chemical elements will form such high-entropy compounds. Here we contribute to understanding this issue by modifying the composition of duodenary TiZrHfNbVCrMoMnFeCoNiAl (12x) alloy in which we recently reported the fabrication of hexagonal C14 Laves phase. We consider three alloys based on 12x: 7x = 12x-VCrMoMnFe, 12x + Sc, 12x + Be and observe that all of them crystalize with the formation of C14 Laves phase as a dominant structure. We report that 12x + Be alloy reveals a single-phase C14 structure with a very high concentration of structural defects and ultra-fine dendritic microstructure with an almost homogenous distribution of the constituted elements over the alloy matrix. The analysis of electrical and magnetic properties reveals that the Laves phases are Curie-Weiss paramagnets, which demonstrate metallic conduction; 7x and 12x alloys also reveal a pronounced Kondo-like anomaly. Analysis of experimental data as well as ab initio calculations suggest that chemical complexity and compositional disorder cause strong s-d band scattering and thus the rather high density of d-states in the conduction band.
Highlights
One of the widely accepted paradigms in modern materials science is the use of multicomponent multi-principal element alloys to design new materials [1,2,3,4,5,6,7]
Analysis of the data reveals that 12x and 12x + Be alloys are single-phase systems in which all diffraction lines can be assigned to a hexagonal C14 Laves phase
We argue that 12x + Sc alloy is a two-phase material with precipitations of C15 cubic Laves phase
Summary
One of the widely accepted paradigms in modern materials science is the use of multicomponent multi-principal element alloys to design new materials [1,2,3,4,5,6,7]. The terms high-entropy alloys (HEAs), complex concentrated alloys, and compositionally complex alloys are used to name such materials. Over the past 15 years of intensive studies of HEAs, the researches have been focused on simple solid solutions (SSSs), such as FCC, BCC, HCP, and their mixtures. Special attention has been given to synthesizing single-phase SSSs and studying their properties and phase stability. Only several tens of single-phase high-entropy SSSs are known [8]. They usually do not demonstrate any exceptional properties and are unable to compete with traditional functional materials
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