High-entropy alloys: preparation, properties and practical application

In recent years, the unique physicomechanical properties of highentropy alloys (HEA) have been the subject of increased attention of Institute of Metallurgy, Ural Branch of RAS, Ekaterinburg, Russia  researchers. The study of the thermodynamic characteristics of such materials may be of interest for formulating the principles of formation of structures with the necessary functional characteristics. Since the processes of structure and phase formation, as well as the diffusion mobility of atoms, the mechanism of formation of mechanical properties and thermal stability are significantly different from similar processes in traditional alloys, that is why HEA are allocated to a special group of materials. Of particular interest are high-entropy alloys based on transition refractory metals such as Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. Light metals such as Ti, V, and Cr are usually selected to reduce the mass density; refractory ones such as Nb , Ta and W, are primarily responsible for the strength characteristics of the entire material. The paper provides a brief overview of results of the study of high-entropy alloys in the new laboratory of Institute of Metallurgy of UB RAS in 2019. Two groups of alloys were studied: HEA of the AlNbTiVZr type containing low-melting aluminum and HEA of the (Ti, V) ZrNbHf (Ta, W) type containing exclusively refractory transition metals. By varying the ratio of components in the first group of HEA, the existence limits of disordered regions of solid solution and intermetallic compounds characteristic of this system were established. For the second group of HEA, a forecast is made of the phase composition, properties and structure based on quantum-chemical calculations involving first-principle molecular dynamics. The forecast showed the possibility or unlikely formation of a disordered solid solution in the above systems with the presence or absence of specific chemical elements.

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