Abstract: In order to develop low-frequency effect and wide-frequency characteristic absorbing materials,Co_xFe_80-xSi₂₀(x=0,10,20,30 mol.%)alloy powders wereprepared by arc melting and high energy ball milling technique with high pure Co、Fe and Si as raw materials.The morphology and phase structure of the powderswere analyzed by Scanning electron microscope(SEM),X-ray diffraction (XRD),andthe effect of the Co content on microwave absorbing properties was investigatedby vector network analyzer.The results show that,Co-Fe-Si alloy powders are mainly composed of α-Fe phase.The value of the reflectivity peaks reduce with the addition of Co and the reflectivity peak frequency move to low frequency withthe grain size of α-Fe increasing.Alloy obtains well low-frequency effect when the addition of Co in the alloy is 20%.The minimum reflectivity and absorbingpeak frequency is -13.4 dB at 4.8 GHz,while the minimum reflectivity and absorbing peak frequency is -14.8 dB at 6.2 GHz,furthermore the bandwidth under -5 dB reach 14 GHz,achieving well wide-frequency effect,when the content of Co is10%.The reflectivity of Co₁₀Fe₇₀Si₂₀ alloy was systematicallystudied,the result shows that the reflectivity peak frequency moves to low frequency with the increasing of material thickness.The reflectivity peak is least when the coatingthickness is 3 mm,which reaches -14.8 GHz at 3.7 GHz.

Key words: Co-Fe-Si alloy, microwave absorbing properties, permeability, reflectivity