Liquid-phase separation of immiscible CrCu x FeMo y Ni high-entropy alloys

Abstract

Taking into consideration the large positive mixing enthalpy of Cu–Mo, in this work, the relative content of Cu and Mo elements was adjusted to investigate the solidification process and microstructure formation of CrCu _x FeMo _y Ni high-entropy alloys. For CrCu_0.5FeMo_yNi (y = 0.5, 1) high-entropy alloys, many Cu-rich spheres were observed in the as-solidified microstructures, while macroscopic phase separation structures were obtained in CrCuFeMo _y Ni (y = 0.5, 1) alloys. Liquid-phase separation occurred in high-entropy alloys when the enthalpy of mixing (ΔH_mix）was positive, the valence electron concentration (VEC) was in a range of 8.09–8.44 and the difference in atomic radii (δ) was between 3.39 and 4.25. For lower positive ΔH_mix, Cu-rich spheres were observed, while for higher positive ΔH_mix, macroscopic phase-separated structures were obtained.