Excellent soft magnetic with high electrical and corrosion resistance properties of Co35Cu5Fe10Ni30Ti20 high entropy alloy

Abstract

High saturation magnetization is a major issue with magnetic high entropy alloys (HEAs) which prevents these materials from being used for industrial applications. In the present study, Co₃₅Cu₅Fe₁₀Ni₃₀Ti₂₀ HEA was synthesized through mechanical alloying and optimized for high saturation magnetization (Ms), low coercivity (Hc), and high electrical resistivity with excellent corrosion resistance through the annealing at different temperatures and for different durations. The as-synthesized HEA possessed the fcc phase, and the values of Ms and Hc were found to be 85 emu/g and 28 Oe, respectively. The synthesized HEA samples were annealed at different temperatures, i.e. 300°C, 500°C, 700°C and 900°C for 2 hr. All the annealed HEA samples except 500°C annealed HEA maintained initial phase identity. For 500°C annealed HEA, an additional bcc solid solution with the as-synthesized fcc phase was appeared. The value of Ms significantly increased with the annealing at different temperatures. Furthermore, we investigated the effect of long-duration annealing on the magnetic properties of the synthesized HEA. The high value of Ms and low value of Hc is obtained, i.e., Ms ∼ 118 emu/g & Hc ∼ 9 Oe and Ms ∼ 122 emu/g & Hc ∼ 2 Oe for 700°C 10 hr and 20 hr annealed HEAs, respectively. We also measured the electrical resistivity and corrosion resistance for 700°C, 20 hr annealed HEA sample and found them to be 319 µΩ and 0.247 mm/year, respectively. Thus, the optimized HEA sample, i.e., 700°C, 20 hr annealed HEA, exhibited an excellent combination of multiple functional properties (i.e., magnetic, electrical, and corrosion properties) that can potentially be used for soft magnetic industrial applications. The optimization through different temperatures and durations of annealing and a detailed insight into the work also opens up new paths for the researchers to design advanced HEAs that can fulfil the future demands of modern industries.