Abstract
FeCoNi(Si0.6Al0.2B0.2) high entropy alloy powders with flaky shapes of 14.7–17.6 μm in mean particle size and 8.2–14.9 in aspect ratio have been prepared by melt-spun and subsequent ball-milling for 10–50 h. The powders possess a mixing structure of BCC nanocrystalline and amorphous phases with average grain sizes of 6–20 nm. The powders exhibit soft magnetic characteristic with saturation magnetization of 78.6–88.1 emu/g. The powders/paraffin (mass ratio = 3:2) composites have high permeability, matchable permittivity, and excellent electromagnetic wave absorption properties in X- and Ku-bands. The composites with thicknesses of 1.2−2.0 mm possess minimum reflection losses (RL) of -38.1 to -44.1 dB with effective absorption bandwidths (RL<10 dB) of 2.5−3.8 GHz.
Highlights
Soft magnetic ferrites have been widely used as EM wave absorbents due to their high permeability (μ), high resistivity and low cost, while the improvement of the EM wave absorption ability in GHz frequency is still a challenge due to their low saturation magnetization (Ms)
Similar to FeSiAl, the metallic Highentropy alloys (HEAs) powders usually have relatively high ε mismatching to the μ, which limits the absorption ability
The increased aspect ratio might be due to the flattening effect induced by the process-control agent (PCA) plays a major role during the milling process
Summary
With the rise of the new generation of wireless communication technology, plenty of electronic devices have been applied in GHz frequency range, and the ensuing electromagnetic (EM) interference and pollution keep increasing. It is of great significance to explore new EM wave absorbing materials suitable for the GHz range. Soft magnetic ferrites have been widely used as EM wave absorbents due to their high permeability (μ), high resistivity and low cost, while the improvement of the EM wave absorption ability in GHz frequency is still a challenge due to their low saturation magnetization (Ms). Flaky FeSiAl6 and FeSiCrAl7 powders with enhanced Ms and μ exhibit good EM wave absorption ability in 2–16 GHz. Soft magnetic ferrites have been widely used as EM wave absorbents due to their high permeability (μ), high resistivity and low cost, while the improvement of the EM wave absorption ability in GHz frequency is still a challenge due to their low saturation magnetization (Ms).. Flaky FeSiAl6 and FeSiCrAl7 powders with enhanced Ms and μ exhibit good EM wave absorption ability in 2–16 GHz. Soft magnetic Fe-based nanocrystalline alloys show excellent high-frequency EM wave absorption performance by virtue of their higher μ in high frequency along with low permittivity (ε) arising from the low conductivity of amorphous phase.. With aim of improving the amorphous-forming ability (AFA) of the FeSiAl alloy and enhance the EM wave absorption ability, a Bbearing FeCoNi(Si0.6Al0.2B0.2) HEA has been designed. The morphology, microstructure, EM parameters and EM wave absorption properties of the powders with different milling time (tm) have been investigated
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