Different annealing treatments for improvement of magnetic and electrical properties of soft magnetic composites

This paper investigates the effect of two steps, annealing and magnetic annealing, on the magnetic and electrical properties of iron powder particles with high purity used in soft magnetic composite materials. It was found that at low frequencies (<10 kHz) the magnetic loss in the high-temperature magnetic annealed state is smaller than that in the low-temperature magnetic, magnetic annealed and without annealing state. On the contrary, the magnetic loss in the high-temperature magnetic annealed state is larger at high frequencies (>10 kHz) than the others. The results showed that magnetic loss of annealed powder was smaller than that of unannealed powder after 100 h milling process. Also, the magnetic loss of samples prepared by two steps milling and annealing process was smaller than samples with one-step process. The magnetic and electrical properties of the cylindrical samples were measured by an LCR meter. Microstructures of the samples were characterized by SEM and XRD.