The role of mixing enthalpy in the formation of physicomechanical properties of solid solution highly entropic alloys

Abstract

The article investigated 37 highly entropic alloys based on BCC and FCC lattices of predominant eviatomic composition. The ingots were obtained by electric arc melting in an atmosphere of purified argon with a non-consumable tungsten electrode on a copper water-cooled hearth in a hole having a hemisphere geometry. The obtained ingots were remelted 6―7 times to homogenize the composition, after which they were cooled directly on the hearth at a speed of 100―200 °C/sec). Using instrumental indentation, the values of hardness and reduced modulus of elasticity are established. Using X-ray phase analysis, the phase composition and lattice parameter are established. The values of the averaged electron concentration, distortion, normalized hardness, and enthalpy of mixing are determined by calculation. The paper presents the characteristics of the elements included in the composition of the investigated highly entropic alloys based on solid solutions with BCC and FCC lattices. Based on the data obtained, the enthalpy of mixing in high-entropy alloys based on solid solutions with BCC and FCC lattices depends on the averaged electron concentration. For highly entropic alloys based on solid solutions with a bcc lattice, the enthalpy of mixing shifts toward negative values with increasing average electron concentration. And for high-entropy alloys based on solid solutions with an FCC lattice ― in the direction of positive values. The effect of mixing enthalpy on the physicomechanical properties of solid solutions with BCC and FCC lattices has been established. Full text download