Raw metal powders with high purity (≥ 99.9%) and small particle size (≥ 200 meshes) were purchased from Aladdin. Section snippets Materials and fabrication This paper provides a strategy for the preparation of EMW absorbing materials with an ultra-wide EAB and good resistance to harsh environments, which is of great significance for the development of materials with a wide EMW absorption band. In addition, the introduction of an appropriate amount of V improved the resistance to high temperature oxidation and corrosive medium. The minimum reflection loss (RL min) values reached − 57.4 dB at 7.5 GHz as thin as 2.24 mm, and the EAB was 6.2 GHz (11.8 −18.0 GHz). The annealed FeCoNiMnV 0.5 HEAs delivered excellent EMW absorption performances. The effect of V content on the phase structure was investigated in detail. In this paper, FeCoNiMnV x (x = 0, 0.25, 0.5, 0.75, and 1) HEAs were prepared by a new 3D high-energy ball-milling method. The work on the influence of V element on the phase structure of FeCoNi-based alloys is relatively few, and the report on EMW absorption property is even blank. It has been reported that the addition of elements such as Ti, Mo, V, and Al causes a noticeable effect on the phase separation in the studied alloys. In order to obtain the desired electromagnetic properties, the composition modification and preparation process are modified to adjust the alloy microstructure.Īccording to the literature, in the multiphase HEAs, each constituent phase has a significant role in the overall properties of the alloy. (2) Due to the lattice distortion effect and hysteresis diffusion effect, amorphous and nanocrystalline structures are easy to be generated in HEAs, which helps to enhance the anisotropy of magnetic crystals, enrich the loss types, and thus enhance the EMW loss capacity. The advantages of flaky HEA EMW absorbers mainly come from two points: (1) The process of grinding the spherical raw materials into sheets produces huge lattice distortion and improves resistivity, which leads to the decreasing of dielectric constant and improvement in impedance matching. Present efforts to enhance the EMW absorber of HEAs concentrate on two aspects: composition adjustment and morphology regulation. However, due to impedance matching and attenuation capabilities, the effective absorption bandwidth (EAB) of present HEA absorbers is very narrow (< 6.0 GHz) compared to many traditional EMW absorbers. The HEAs prepared by the mechanical alloying method not only have a uniform element distribution but also have a high aspect ratio, so they have good EMW absorption ability. The design principle of "equimolar or nearly equimolar proportions of constituent elements" gives HEAs extraordinary tunability (cocktail effect). HEAs typically include five or more primary elements, have equimolar or nearly equimolar ratios, and form simple solid solutions with face-centered cubic (FCC), body-centered cubic (BCC), or hexagonal close packed (HCP) structures. Therefore, as a new generation of EMW absorbers, magnetic high entropy alloys (HEAs) with good permeability and permittivity have garnered considerable attention in the development of EMW absorbers due to their superior overall mechanical qualities, corrosion resistance, and oxidation resistance. The new generation of EMW absorbers should not only meet the traditional requirements of light weight, wide absorption band, thin thickness, and strong absorption, but also be able to work in harsh environments. The traditional EMW absorbers, such as ferrites, , carbon materials, , transition metal disulfides, ,, , conductive polymers, , and other materials, , have become more and more difficult to meet the requirements. With the development of society, the requirement for electromagnetic-wave (EMW) absorbers becomes higher. Excessive electromagnetic radiation has harmful effects on electronic products, the natural environment, and even human health.
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