Synthesis and electromagnetic wave absorption properties of FeCoNi(Si0.6Al0.2B0.2) high-entropy nanocrystalline alloy powders

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.