CoCrFeNi is one of the most studied HEA alloys. It has a narrow solidification temperature range and is single phase disordered FCC_A1 across a wide temperature range. An ordered precipitate phase could increase its high temperature strength. Thermo-Calc can be used to explore chemistry ranges and modifications to tailor phase balance for optimum properties.
This phase diagram for CoCrFeNi-Alx shows how additions of Al change the phase stability. At higher amounts of Al, ordered BCC_B2 phase is predicted to be stable. At even higher Al contents, the matrix phase switches to a BCC_A2 disordered phase.