Effects of Annealing Temperature and Epoxy Resin Encapsulation on Soft Magnetic Properties of Fe₇₈Si₉B₁₃ Amorphous Alloy

Fe78Si9B13 amorphous strips with 20 mm width and 25 μm thickness were prepared by single-roller method. Magnetic cores were gained by coiling the amorphous strips, and then were annealed at 350, 400, 450, 500 ℃, respectively. Magnetic core annealed at 400 ℃ was encapsulated using epoxy resin, and the effects of annealing temperature and epoxy resin encapsulation on the soft magnetic properties were studied. The results show that the initial magnetic permeability (μi), saturation magnetization (Bs) and coercivity (Hc) all increased at first and then decrease with the increase of annealing temperature. The comprehensive soft magnetic properties of Fe78Si9B13 amorphous alloy annealed at 400 ℃ show the best (μi=0.008 3 H·m-1, Bs=1.517 T and Hc=15.73 A·m-1. The μi and Bs of Fe78Si9B13 amorphous alloy all decreased and its Hc increased after epoxy resin encapsulation. The magnetizaion curve and hysteresis hoop of Fe78Si9B13 amorphous alloy after encapsulation were mainly the same with those before encapsulation.