Effect of annealing temperatures on phase evolution and magnetic properties of Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ high entropy alloys

Design and development of novel high entropy alloys (HEAs) having balance magnetic properties with other functional properties are vital for industrial applications of these alloys. In this study, a novel Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA was synthesized through mechanical alloying and studied for phase evolution and its effects on magnetic properties with annealing at different temperatures. As-synthesized HEA has a major fcc phase with minor concentrations of bcc and R phases. The as-synthesized HEA is also annealed at different temperatures of 500, 700 and 900°C and found that the phase identity of formed phases maintained after annealing. However, for HEA annealed at 1000°C, slight amount of new σ-phase has formed along with initial phases. Values of M_s and H_c were found to be 75 emu g⁻¹ and 18 Oe for as-synthesized Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA. We found that after annealing at different temperatures, magnetic properties of Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA show significant improvement. Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA annealed at 900°C exhibited good soft magnetic characteristics with high M_s (99 emu g⁻¹), low values of H_c (3.8 Oe) and M_r (0.45 emu g⁻¹), as compared to other samples developed in the present study. Thus, designed and developed 900°C annealed Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al₁₅ HEA can be further used for magnetic switching applications due to the high value of M_s and low value of M_r.