Cooling Rate Effects on the Microstructure, Magnetic Properties, and DC Superposition Behavior of NiCuZn Ferrites

This study investigated the cooling rate effects on the magnetic properties of NiCuZn ferrites. A copper‐rich phase segregated near the grain boundaries during sintering was observed. The amount of copper‐rich precipitates depends strongly on the cooling rate and decreases with decreasing cooling rate. The quenched sample exhibited superior initial permeability and DC ‐bias‐superposition characteristics due to the highest saturation magnetization and a thick nonmagnetic second phase segregated at the grain boundaries. A NiCuZn ferrite with superior initial permeability and DC superposition characteristics can be obtained by controlling the cooling rate to adjust the copper‐rich precipitate thickness at the grain boundaries.