Overview of the High-Entropy Alloys Concept

Abstract

The article presents a review of the results of research on high-entropy alloys, describing the principles of their formation, the basic concepts and properties of high-entropy alloys. The existing categories of the entropic alloys are listed. The effects resulting from the formation of high-entropy alloys are described: high entropy, lattice distortion, sluggish diffusion and cocktail effects. It is noted that the traditional thermodynamic representations for multicomponent alloys require additions. It is also noted that the application of Hume-Rothery rules to predict the phase composition of high-entropy alloys shows some difficulties, since it is difficult to select a large number of elements having the same type of lattice and valence. The results of the analysis of a number of parameters and conditions which, according to the researchers' opinion, affect the structural state created by high-entropy alloys, taking into account which could allow to correctly predict the formation of structures in high-entropy. Analysis of the literature data has shown that at present there is no universal parameter that could allow the correct prediction of the formation of structures in multicomponent alloys systems. Methods for the preparation of powders of high entropy alloys are presented. The results of frequently used methods of obtaining coatings on the basis of high-entropy alloys, such as laser cladding, magnetron sputtering, electrochemical deposition and thermal spraying are reviewed. Disadvantages of obtaining coatings methods are described.