Nano FeCoNi-based high-entropy alloy for microwave absorbing with high magnetic loss and corrosion resistance

With the development of modern communication and military technology, the protection of electromagnetic wave pollution and radar stealth technology have been widely concerned. In this background, the magnetic metals were widely used due to the strong ferromagnetism, which can induce strong magnetic loss to the electromagnetic wave. However, it remains challenging to precisely control the wave-absorbing performance of individual magnetic metals, and there are issues with poor corrosion resistance and high temperature resistance. Therefore, the alloy powders based on Fe, Co, and Ni in this work were prepared by wet chemical method at room temperature. Different from most of the traditional powder metallurgy methods, the wet chemical method enables us to obtain binary, ternary and quaternary alloys with a nanometer-scale and uniform distribution, all products have a microscopic morphology of 300-500 nm spheres. The FeCoNi alloy powder shows an effective absorption band (RL<-10dB) of 7 GHz in the high frequency electromagnetic wave range at an ultrathin thickness of 1.5 mm, which has a high temperature magnetism (Tc >900 K) and excellent corrosion resistance. Further doping of Cu to form a quaternary alloy can improve the corrosion resistance and maintain the original wave-absorbing properties, while doping of Mo and Sn can adjust the position of the effective absorption bandwidth.