Review of alloys developed using the entropy approach

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 2 2021 [65], Sanin. Yukhvid et al. [71], Gorbachev, Popov et al. [146], Trofimenko et al. [26], Vinnik et al. [44, 138] deserve attention. Russian-speaking specialists will also benefit from reviews presented in thesis research carried out at the Belgorod State National Research University by Shaisultanov [82], Klimova [21], Yurchenko [147], as well as at the Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences by Ivchenko [102]. Conclusion The branch of materials science focused on the study of the structure and properties of multicomponent systems, the elements of which are present in equiatomic or close to it ratios, can be defined as a new, intensively developing one. The principles underlying the formation of the structure of multicomponent equiatomic alloys are radically different from the approaches that were previously used in the development of other types of metal materials. The initially formulated concept of creating high-entropy alloys, according to which the high entropy of mixing ensures the formation of disordered substitution solid solutions and suppresses the formation of intermetallides and ordered phases, has undergone fundamental changes. Later experimental studies have shown that a high level of entropy of mixing is not the determining criterion for structure formation in multicomponent alloys. At the same time, obtaining a single-phase structure of a solid solution is currently not a mandatory requirement for the HEAs being developed. The data presented in the literature on the structure of multicomponent materials, the criteria for its stability, and the influence of processing parameters on the structure and complex of properties are ambiguous. Based on numerous studies of multicomponent alloys, no universal parameter has been proposed and no combination of several parameters has been identified, taking into account which it would be possible to predict the structure, and, consequently, the properties of materials, with a high degree of reliability. Accurate prediction of the phase composition of high-entropy alloys is currently not achieved by any of the approaches or methods available to specialists. References 1. Yeh J.-W. High-entropy multielement alloys . Patent US, no. US 20020159914 A1, 2002. 2. Yeh J.-W., Chen S.-K., Lin S.-J., Gan J.-Y., Chin T.-S., Shun T.-T., Tsau C.-H., Chang S.-Y. Nanostructured high- entropy alloys with multiple principal elements: novel alloy design concepts and outcomes. Advanced Engineering Materials , 2004, vol. 6, pp. 299–303. DOI: 10.1002/adem.200300567. 3. Cantor B., Chang I.T.H., Knight P., Vincent A.J.B. Microstructural development in equiatomic multicomponent alloys. Materials Science and Engineering: A , 2004, vol. 375–377, pp. 213–218. DOI: 10.1016/j.msea.2003.10.257. 4. Yeh J.W. Recent progress in high-entropy alloys. Annales de Chimie-Science des Materiaux , 2006, vol. 31, pp. 633–648. DOI: 10.3166/acsm.31.633-648. 5. Yeh J.-W., Chen Y.-L., Lin S.-J., Chen S.-K. High-entropy alloys – a new era of exploitation. Materials Science Forum , 2007, vol. 560, pp. 1–9. DOI: 10.4028 /www.scientific.net/MSF.560.1. 6. Yeh J.-W., Chen S.-K., Gan J.-Y., Lin S.-J., Chin T.-S., Shun T.-T., Tsau C.-H., Chang S.-Y. Formation of simple crystal structures in Cu-Co-Ni-Cr-Al-Fe-Ti-V alloys with multiprincipal metallic elements. Metallurgical and Materials Transactions: A , 2004, vol. 35, pp. 2533–2536. DOI: 10.1007/s11661-006-0234-4. 7. Kuznetsov A.V., Salishchev G.A., Sen’kov O.N., Stepanov N.D., Shaisultanov D.G. Vliyanie mikrostruktury na mekhanicheskie svoistva pri rastyazhenii vysokoentropiinogo splava AlCoCrCuFeNi [Microstructure influence on tensile mechanical properties of an AlCoCrCuFeNi high-entropy alloy]. Nauchnye vedomosti Belgorodskogo gosudarstvennogo universiteta. Matematika. Fizika = Belgorod State University Scientific Bulletin. Mathematics and Physics , 2012, vol. 11 (27), pp. 191–205. 8. Zhang Y. High-entropy materials: a brief introduction . Singapore, Springer Nature, 2019. 159 p. ISBN 978- 981-13-8526-1. 9. Zhang Y., Zuo T.T., Tang Z., Gao M.C., Dahmen K.A., Liaw P.K., Lu Z.P. Microstructures and properties of high-entropy alloys. Progress in Materials Science , 2014, vol. 61, pp. 1–93. DOI: 10.1016/j.pmatsci.2013.10.001.