Enhanced microwave absorption performances of FeCoNiCuCr high entropy alloy by optimizing particle size dehomogenization

FeCoNiCrCu high entropy alloy (HEA) powder was prepared by high energy ball milling mechanical alloying. The phase structure, microstructure, particle size, magnetic properties and electromagnetic parameters of the powder were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), laser scattering, vibrating sample magnetometer and vector network analyzer. The results show that the particle size can be controlled effectively by changing the grinding time, and the variation of particle size and uniformity induces the change of magnetic property and electromagnetic parameters, thus regulating the absorption performance of the powder. It is found that the smaller particle size and the worse uniformity of the powder correspond to the better microwave absorption performance. For the 50 h milling sample, the average particle size is 3.15 µm and the uniformity of the powder is the worst among the three 40 h, 50 h and 60 h milled samples. The minimum reflection loss (RLmin) is − 41.23 dB at 6.4 GHz, and when the thickness is 2.6 mm, the maximum effective absorption bandwidth (EAB) is 4.5 GHz (7.2 GHz∼11.7 GHz), covering the entire X band.