Production, Properties and Practical Application of High-Entropy Alloys

In recent years, the unique physico-mechanical properties of high-entropy alloys (HEAs) have increasingly attracted the attention of researchers. The thermodynamic characteristic study of these materials for formulating the formative principles of structures with necessary functional characteristics is an interesting topic. HEAs are referred to a special group of alloys because they are characterized by significantly different structure and phase formation processes, diffusion mobility of atoms, formation of mechanical properties, and thermal stability when compared to their conventional counterparts. High-entropy alloys based on transition refractory materials, such as Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, are particularly interesting to consider. Light metals, such as Ti, V, and Cr, are chosen for reducing the mass density. Whereas refractory metals, such as Nb, Ta, and W, are primarily responsible for the strength characteristics of the entire material. This paper presents a brief overview of the results of testing high-entropy alloys at a new laboratory of the Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences (IMET UB RAS) in 2019. The two groups of alloys tested were AlNbTiVZr HEAs with easily fusible aluminum and (Ti,V)ZrNbHf(Ta,W) HEAs with solely refractory transition metals. For the first group of HEAs at varying component ratios, the tests determined the existence limits of disordered regions of solid solution, as well as the intermetallic regions typical of this system. The predicted phase composition, properties, and structure of the second group were determined by quantum chemical calculations, involving first-principle molecular dynamics. The prediction showed that the formation of disordered solid solution in the foregoing systems with or without concrete chemical elements was either possible or unlikely.