Effect of neodymium and yttrium addition on microstructure and DC soft magnetic property of dual-phase FeCoNi(CuAl)0.8 high-entropy alloy

The correlation between the microstructure and soft magnetic properties under the direct current (DC) mode of dual-phase FeCoNi(CuAl)0.8RE0.05 (RE = Nd, Y) high-entropy alloys (HEAs) was investigated. X-ray diffraction (XRD) and electron backscattered diffraction (EBSD) results show that all samples consist of face-centered cubic (FCC) and body-centered cubic (BCC) phases. In comparison to the volume fraction of BCC phase of the RE-free HEA (25.3%), Nd and Y additions dramatically increase it to 42.0% and 43.3%, which leads to an increase of the saturation magnetization. RE addition reduces the average grain size from 7.26 μm of the RE-free HEA to 5.42 μm of RE = Nd HEA and 4.88 μm of RE = Y HEA. Stripe magnetic domain structure is observed in both FCC and BCC phases in the RE-free and RE-containing HEAs. The additives of Nd and Y both decrease the stripe pattern width in FCC and BCC phases. The refined structure and finely spaced stripe domain by RE addition can decrease the remanence. Compared with the RE-free HEA, RE addition can effectively enhance the DC soft magnetic property by decreasing the remanence, the coercivity, and the hysteresis loss.