Effect of annealing on microwave absorption properties of Fe–B–P amorphous alloys

Fe-based amorphous alloys play an important role in microwave absorption. In this study, submicron amorphous Fe–B–P particles were prepared by chemical reduction method and annealed at high temperature in nitrogen atmosphere. The effects of annealing temperature on the microstructure, magnetic, and microwave absorption properties of the particles were studied. The results show that the non-annealed Fe–B–P particles are monodisperse spherical particles with an average particle size of 0.7 μm. The DSC curve presents the crystallization temperature of 450 °C, and the XRD patterns show crystallization after annealing at 450 °C. The magnetic properties and microwave absorption properties of Fe–B–P submicron particles were improved during annealing before crystallization. The values of saturation magnetization range from 103.04 emu/g (non-annealed) to 127.70 emu/g (annealing at 400 °C). After annealing at 200 °C, the Fe–B–P absorbers with 2.8–5 mm thickness exhibit good microwave absorption performance (reflection loss < − 20 dB) in the frequency range of 2.32–4.27 GHz, and the optical reflection loss of − 59.95 dB was obtained at 3.38 GHz with an absorber thickness of 3.56 mm. These results suggest that the amorphous nanostructures may be promising candidates as high-efficient microwave-absorbing materials.