Features of phase and structure formation in high-entropy alloys of the AlCrFeCoNiCu x system (x = 0, 0.5, 1.0, 2.0, 3.0)

Alloys of the AlCrFeCoNiCu x system (x = 0, 0.5, 1.0, 2.0, 3.0) were smelted by argon-arc smelting in pure argon. The phase composition and structure of fabricated alloys are investigated and their mechanical properties are determined. The results showed that an increase in the amount of copper in alloys leads to a change in the phase composition from single phase (bcc) to three phase (bcc + fcc1 + fcc2), which is accompanied by the structural change from coarse-grain polygonal structure to complex dendritic structure (primary dendrites (DR) + secondary dendrites (SDR) + interdendrite phase (ID)). The region of electron concentrations of alloys, in which bcc and fcc phases are present simultaneously, is determined. The limiting electron concentration of stability of the bcc lattice is found experimentally. Microhardness is measured and Young moduli of alloys over the entire range of varying the copper concentration are determined.