Investigating electrical and magnetic properties of spark plasma sintered (FeCoNi)₇₅Cu_25−xSi_x high entropy alloys

The study examines the electrical and magnetic properties of (FeCoNi)₇₅Cu_25−xSi_x high entropy alloys (HEAs) produced through mechanical alloying and spark plasma sintering. Unlike prior research that primarily focused on other elements, this work explores the understudied impact of Cu and Si on FeCoNi-based HEAs. The Si concentrations vary at different percentages, and the alloys are categorized as Si₀, Si₅, Si₁₀, Si₁₅, Si₂₀, and Si₂₅. The results indicate the presence of FCC structure in Si₀, Si₅, and Si₁₀ alloys, while Si₁₅, Si₂₀, and Si₂₅ alloys exhibit different phases. The electrical resistivity shows a non-monotonic trend with increasing Si content. While it significantly increases from Si₀ (17.9 µΩ m) to Si₁₀ (46.3 µΩ m), a slight decrease is observed for Si₁₅ (41.2 µΩ m). Magnetic characterization shows a constant permeability of approximately 4.3 at 1 kHz for Si concentrations below 15%, but a decrease in permeability is observed for alloys with higher Si content (Si₂₀: 3.75 and Si₂₅: 3.96). A resonance phenomenon within the 100–500 kHz frequency range shows that eddy current losses dominate the total energy loss within these HEAs. These findings suggest the potential for tailoring the electrical and magnetic properties of Si-doped HEAs through controlled Si content, potentially leading to the development of novel materials with specific electromagnetic functionalities.