FeCoNiCuZn HEA was synthesized through induction melting, using high purity (>99.99%) 16 metal chips. In brief, Fe, Co, Ni, Cu, and Zn chips were mixed in a stoichiometric ratio of 17 1:1:1:1:1, loaded into an alumina crucible, and melted in an induction furnace at 1250 °C for 10 18 min under an inert atmosphere. The obtained sample was then remelted in a muffle furnace at 19 1000 °C for 96 h to attain a single-phase structure, with homogenous composition. The resulting 20 melt was then naturally cooled to room temperature, following which it was subjected to ball 21 milling for 12 h in a planetary mill to obtain the FeCoNiCuZn HEA powder. Germany). X-ray photoelectron spectroscopy (XPS) measurements were conducted using 13 Thermo Scientific Nexsa surface analysis system (Thermo Fisher Scientific Inc., United States).