Microstructure and high-temperature soft magnetic properties of nanocrystalline (Fe0.65Co0.35)78.4Si9B9Nb2.6Cu1 alloy

Structural characteristics and high-temperature soft magnetic properties of nanocrystalline (Fe0.65Co0.35)78.4Si9B9Nb2.6Cu1 alloy were investigated. A two-phase nanocrystalline structure composed of the amorphous matrix and the α-FeCo nanocrystallites was obtained by annealing samples at different temperatures from 460 °C to 640 °C for 0.5 h. The temperature evolution of initial permeability was described from room temperature to 730 °C. Coercivity (Hc) and saturation magnetic induction (Bs) were obtained by means of hysteresis loops measurements at room temperature. Results showed that the samples annealed at 550–640 exhibited the improvement of the high-temperature soft magnetic properties. The microstructure exerted a significant effect on the high-temperature magnetic properties. These experimental results were discussed by means of the mechanism of the two-phase random anisotropy model and the exchange coupling through the intergranular amorphous layer.