A simple method for preparing flaky FeSiAl for low-frequency electromagnetic wave absorber

The effect of morphology and size on electromagnetic wave (EMW) absorption performance has been a relent-lessly explored issue. By grinding the spherical FeSiAl alloy powder in a planetary ball mill, a flaky FeSiAl alloy with higher saturation magnetization, dielectric constant, magnetic permeability, and better impedance matching at low frequency was prepared. The phase composition, morphology, and static magnetism of FeSiAl alloys with different morphologies were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The electromagnetic parameters and absorption properties of the two kinds of powders were studied using a vector network analyzer (VNA). The results show that the crystallinity, dielectric constant, and magnetic permeability of the flaky FeSiAl powder increase compared with the spherical one. The absorption performance in the low-frequency band was remarkably improved after grinding. When the matching thickness is 6.5 mm, the reflection loss at 1 GHz reaches-16.89 dB for the flaky FeSiAl. The excellent EMW absorption performance of flaky FeSiAl alloy powder at low-frequency is mainly due to the large magnetic permeability and magnetic loss which is derived from the magnetocrystalline anisotropy brought about by lamellar morphology and appropriate impedance matching as well. This work provides a new idea for the preparation of low-frequency absorbing materials expected to be used in the L-band wave absorption field.