Studies on structural, magnetic and corrosion properties of Novel Co35Cr5Fe10Ni30Ti5Al10-x Mn5+x (x = 0, 2.5, 5) high entropy alloys

Abstract

We investigated the effect of the presence of both Mn and Al on magnetic and corrosion properties of Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al_10-xMn_5+x (x = 0, 2.5, 5) High Entropy Alloys (HEAs). Three different HEAs were synthesized through the mechanical alloying technique and investigated for the phase formation, and its correlation with the magnetic properties. At the as synthesized stage a single fcc phase is formed due to the addition of 7th alloying element in Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al_10-x Mn_5+x (x = 0, 2.5, 5) HEAs. However, after annealing at 700 ̊C for 2 h, a small amount of bcc and σ-phase are precipitated along with the fcc phase for the Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al_10-xMn_5+x (x = 0, 2.5, 5) HEAs. The value of Ms and Hc are found 73 emu/g & 18 Oe, 71 emu/g & 15 Oe and 71 emu/g & 17 Oe for the as- synthesized Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al_10-x Mn_5+x HEAs (x = 0, 2.5, 5) respectively. However, after annealing of the as synthesized HEA at 700℃ 2 h, the value of Ms (102–106 emu/g), Hc (47–49 Oe) and Mr (2.26–2.48 emu/g) are increased significantly. The increment in the value of Ms for the annealed HEAs is associated with the decrease in the lattice parameter and dislocation density of the fcc phase as compared to the as- synthesized HEAs. We also investigated the corrosion resistance of annealed Co₃₅Cr₅Fe₁₀Ni₃₀Ti₅Al_10-x Mn_5+x (x = 0, 2.5, 5) HEAs and found good corrosion resistance for the developed HEA as compared to the recently reported HEAs and conventional soft magnetic materials.