Tailoring AC magnetic properties of FeCoNi(MnSi)x (0 ≤ x ≤ 0.4) high-entropy alloys by the addition of Mn and Si elements

In this work, we investigate the evolution with x of the microstructure and alternating current (AC) magnetic properties of FeCoNi(MnSi)(x) (0 <= x <= 0.4) high-entropy alloys (HEAs) with the motivation of exploring the potential applications of soft magnetic HEAs. The suitable addition of MnSi improves AC remanence (AC B-r), AC coercivity (AC H-c) and especially specific total loss (P-s) while it suppresses amplitude permeability (mu a) and AC maximum magnetic flux density (AC B-m), which suggests that the HEAs can be used as a new soft magnetic material with low Br and low Hc. Ps can be divided into two parts: hysteresis loss (P-h), eddy current loss (P-e), and further studies show that the P-h plays an important role at the frequency of 50 Hz, while the P-e is dominant in the total losses when the frequency is 950 Hz. This provides the direction of efforts to reduce the P-s. The XRD, SEM and TEM results show that these alloys contain simple FCC structure, but a new Mn6Ni16Si7 intermetallic compound appears when x >= 0.3, and it has a big influence on the AC magnetic properties of HEAs. (C) 2019 Elsevier B.V. All rights reserved.