High-entropy alloys (HEAs) are materials which utilize the entropy of mixing to encourage immiscible elements to form single-phase solid solutions. These materials have shown superior structural and mechanical properties, especially at high temperatures, but there is increasing interest in their potential in functional applications such as memory storage and energy devices. In the current work, we investigate the magnetic properties of HEAs and proto-HEAs ${\mathrm{Al}}_x\mathrm{CoCrFeNi}$ ($0\le x\le 2$). These materials form a single phase at $x<1$ but phase separate at higher concentrations. Interestingly, with phase separation, the magnetic moment and Curie temperature increase with the inclusion of the nonmagnetic aluminum. The phase separation and the resulting magnetic evolution are investigated at elevated temperatures with scanning transmission electron microscopy and small-angle neutron scattering. These complementary techniques provide a comprehensive understanding of both the compositional and magnetic phase separation. First-order reversal curve analysis is used to correlate the temperature-dependent phase separation with the magnetic coupling and reversal behavior.

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• Magnetism
• Alloys
• Small angle neutron scattering