The objective of this work was to provide information about the behaviour of Fe-based nanocomposites when exposed to microwaves. It is about rectangular bulk samples of epoxy resin reinforced by nanocrystalline Fe powders and shaped in accordance to the internal section of the R100 metallic waveguide (8.2 to 12.4 GHz) at a fixed thickness of 7 mm. The nanocrystalline Fe powders were obtained by high-energy mechanical milling process using a planetary Retsch PM 400-ball mill. The milling speed was fixed at 200 rpm for three durations and the milling process were performed under Argon atmosphere. The bulk nanocomposites were obtained by dispersion of 30% vol. of the nanocrystalline Fe powders in the resin matrix. Electromagnetic parameters as complex relative dielectric permittivity and magnetic permeability, electric and magnetic loss tangent and reflection loss were calculated using reordered S parameters. The scattering parameters were characterized using a measure cell made off two metallic R100 wave-guides associated to an Agilent 8719 network analyser according to the reflection-transmission technique. The obtained spectra inform on the new electromagnetic properties as well as the absorption characteristic acquired by the bulk nanocomposites due to the presence of the nanocrystalline Fe powders.

Microwave absorbing materials are applied in stealth, communications and information processing technologies. This kind of material dissipates an electromagnetic wave by converting it into thermal energy. The nanostructuration of materials became a reliable route over the years to enhance the dielectric and magnetic properties, which induce the required interaction. Nanostructured Fe-Co alloys are soft magnetic materials that make them promising candidates for microwave absorption when combined with other materials. The aim of our study was therefore to investigate the microwave absorption properties of based nanocomposites. The nanocomposites were obtained by the solution dispersion method. Nanocrystalline alloys elaborated by mechanical alloying (MA) in a high-energy planetary ball mill (RETSCH PM400) were dispersed into commercial epoxy resin matrix to form thin polymer nanocomposites. The grain size refinement and structural properties changes during milling process were characterized using powder’s X-ray Diffraction (XPERT PRO MPD diffractometer) at different milling durations. XRD spectra analysis show that a grain size refinement of 4.54 nm was reached after 60h milling accompanied with 1.2 % microdeformations. Obtained powders were shaped in small discs for which resonant cavity measurements were undertaken. The based nanocomposites have been subject to an experiment of two-port S parameters measurement in a rectangular waveguide (R120). The microwave experiments involved a Network Analyzer (VNA). Obtained results in terms of reflection losses show a good absorbing characteristic over the [8-15] GHz microwaves band.