Novel Fe1.1Co1.1(CrAlx)1.8Gd0.1 high-entropy alloy absorber: Noticeable ferromagnetic transformation and enhanced magnetic loss

Abstract

High-entropy alloys (HEAs) with excellent soft magnetic properties are gradually emerging as a new generation of electromagnetic wave (EMW) absorption materials. Existing HEAs still cannot efficiently absorb EMW due to inadequate magnetic properties. This paper aims to modulate the ferromagnetic properties of Fe1.1Co1.1(CrAlx)1.8Gd0.1 (x=1, 1.2, 1.4, 1.6) to enhance the permeability and achieve efficient absorption of EMW. The experimental results show that when the ratio of Al to Cr is 1.6:1, the saturation magnetization and permeability reach their highest values. First-principles calculation confirms from an atomic perspective that when the ratio of Al to Cr is 1.4:1, Gd begins to undergo a ferromagnetic transformation. Its magnetic moment increases from −1.2μΒ to 1.4μΒ, and the degree of electron localization also increases. The Fe1.1Co1.1Cr0.75Al1.05Gd0.1 achieves an effective absorption of −51 dB at a thin thickness of 2 mm and an effective absorption bandwidth of 6.2 GHz of 1.4 mm. The cocktail effect also depends on having good corrosion and oxidation resistance. This paper provides theoretical guidance for the design of high-performance soft magnetic EMW absorption materials.