Tailoring magnetic property and corrosion resistance of FeCoNiCuAl high-entropy alloy with Ce additive

Abstract

The FeCoNiCuAl high-entropy alloy (HEA) has good magnetic and –mechanical properties which can be finely tuned by the fraction, composition, and distribution of the BCC and FCC phases. In this paper, we report the magnetic properties, corrosion resistance, and microstructure of the FeCoNiCuAlCex (0 ≤ x ≤ 0.09) HEAs. The results show that Ce addition is beneficial to the remanence (Br), coercivity (Hc), and hysteresis losses (Pu), but detrimental to the maximum permeability (μm) and maximum flux density (Bm). When x = 0.09, the Br, Hc, and Pu of the HEAs are improved by about 91%, 64% and 91%, respectively. The FeCoNiCuAl HEA has good corrosion resistance, comparable to 304 stainless steels. The addition of Ce improved the Icorr of the HEAs. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) results show that the FeCoNiCuAl HEAs are composed of a face-centered cubic (FCC) phase and a body-centered cubic (BCC) phase, with the Cu-rich nano-precipitates embedded in the BCC phase. With the addition of Ce, the nano-precipitates become even smaller and more uniform. Meanwhile, the FCC phase becomes Cu-rich and its magnetism changes from ferromagnetic to non-ferromagnetic. The electronic density of state (DOS) for the alloys calculated by density functional theory (DFT) is discussed.