Effect of crystallization condition on the Microwave properties of Fe-based amorphous alloy flakes and polymer composites

The electromagnetic (EM) wave absorption properties with a variation of crystallization temperature have been investigated in a sheet-type absorber made of the amorphous Fe₇₃Si₁₆B₇Nb₃Cu₁Finemet powder. With the variation of the annealing temperature, the magnetic and dielectric properties of the crystallized Fe-based absorber with a nano-structure were changed. The complex permittivity increased with increasing the annealing temperature, whereas the complex permeability was maximized after annealing at 530°C for 1 hour. The absolute value of the reflection parameter, |S₁₁|, increased with increasing annealing temperature of the nanocrystalline alloy powder. On the contrary, the transmission one, |S₂₁|, showed the highest value after annealing at 530°C for 1 hour, which is regarded as the optimum temperature for the improvement of EM wave absorption properties.