• FeCoNi medium entropy alloy (MEA) was successfully synthesized via sol–gel and co-precipitation precursors followed by carbothermal and hydrogen reduction at 1500°C.
• Hydrogen reduction yielded a more uniform and higher-purity FeCoNi MEA compared to carbothermal reduction, which introduced carbon contamination.
• The hydrogen-reduced FeCoNi MEA exhibited superior soft magnetic properties, with higher saturation magnetization and lower coercivity, making it promising for magnetic storage applications.
• The liquid-phase precursor approach offers a cost-effective and environmentally friendly route for producing FeCoNi MEA, potentially utilizing waste Fe, Co, and Ni resources.