Effects of aspect ratio and particle size on the microwave properties of Fe–Cr–Si–Al alloy flakes

The structural and electromagnetic properties of gas atomized Fe–Cr–Si–Al alloy (SMSS) powders flattened by ball milling were studied. It is found that the aspect ratio of the powders with the same particle sizes of 48–55 μm increases with the milling time. With the increase of the aspect ratio, the complex permittivity, permeability and intensity of reflectivity peak increase, respectively, and the matching frequency shifts to low frequency due to the improved wave impedance matching and the increase of real part of complex permittivity and permeability. A similar trend of the microwave properties with the decrease of the particle size can be also observed.