High Entropy Alloys: Structure, Mechanical Properties, Deformation Mechanisms and Applications

A brief review of publications by foreign researchers on the study of the structure, phase composition and properties of five-component high-entropy alloys (HEAs) in different structural states in a wide temperature range over the past two decades has been made. HEAs attract the attention of scientists with their unique and unusual properties. Difficulties in conducting a comparative analysis and summarizing data due to different methods for obtaining HEAs, modes of mechanical tests for uniaxial compression and tension, sample sizes and shapes, types of heat treatments, and phase composition (BCC and FCC lattices) are noted. It is noted that HEAs with the BCC lattice have predominantly high strength and low ductility, while HEAs with the FCC lattice have low strength and increased ductility. It is shown that a significant increase in the properties of HEA FeMnCoCrNi with the FCC lattice can be achieved by doping with boron and optimizing the parameters of thermomechanical treatment when doping with carbon in an amount of 1% (at %). The deformation curves analyzed in the temperature range of –196…800°C indicate an increase in the yield strength with a decrease in the grain size from 150 to 5 μm. As the temperature decreases, the yield strength and relative elongation increase. The effect of the deformation rate on the mechanical properties consists in an increase in the tensile strength and yield strength, which is most noticeable at high rates of 10–2–103 s–1. The features of the deformation behavior of HEAs in single- and polycrystalline states are noted. The complex of high operational properties of HEAs provides the possibility of their application in various industries. The prospects for using energy treatments to modify surface layers and further improve the HEAs properties are noted.