Microwave Permeability and Mössbauer Spectra of Flaky Fe–Si–Al Particles

Fe_84.94Si_9.68Al_5.38 flaky particles have been obtained by ball attrition method. The volume fraction dependence of microwave permeability has been measured for composites filled with these particles. Effective medium theories have been employed to extract the apparent microwave permeability. It is found that the flaky Fe-Si-Al particles have large apparent microwave permeability and large microwave magnetic loss. For example, at 0.5 GHz, the real and imaginary parts of apparent permeability are 10 and 5, respectively. The extracted microwave permeability is found to be consistent with generalized Snoek´s limit. Due to high microwave magnetic loss, the flaky Fe-Si-Al particles can be useful for technical applications in the field of electromagnetic compatibility. Mössbauer spectroscopy measurements show that the hyperfine magnetic field and isomer shift have wide distribution, indicating that Fe atoms in the flaky Fe-Si-Al alloys have complicated environments.