Mechanically alloyed (FeCoNi)75Cu25−xSix high entropy alloys: Phase evaluation and magnetic properties

The present paper studies the influence of Si addition on the microstructure and magnetic properties of (FeCoNi)75Cu25−xSix (x = 0, 5, 10, 15, 20, 25 at. %) alloys synthesized by mechanical alloying. In addition to thermodynamic and physical parameters, X-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy were used to evaluate the phases in various alloys. Vibrating sample magnetometers were used to determine the magnetic properties. Following 40 h of milling, all alloys showed the FCC structure, but the alloy with 20 at. % Si revealed the NiSi2 intermetallic phase. In all alloys, Fe, Co, Ni, and Si were distributed homogeneously except in the alloy with 20 at. % Si, where some islands of Si were observed. The distribution of Cu in the alloys was not uniform, and some areas were enriched in Cu. All alloys exhibited a semi-soft magnet behavior. The coercivity increased significantly from 17 to 61 Oe with an increase in Si from 0 to 25 at. %. When Si increased from 0 to 20 at. %, saturation magnetization slightly fluctuated (around 94 emu/g), then sharply declined from 95 to 74.97 emu/g when Si increased from 20 at. % to 25 at. %. •The (FeCoNi)0.75Cu0.25−xSix HEAs are fabricated successfully by mechanical alloying.•Except for Si0.2, which forms NiSi2 intermetallic, all alloys showed FCC structures.•The crystallite size and lattice parameter decrease and lattice strain increases with Si.•Semi-soft magnetism was observed in all alloys.•As Si increases, coercivity increases, while saturation magnetization fluctuates.