It is now known that the magnetic properties of HEAs are significantly affected by the processing parameter. A selected Co35Cr5Fe10Ni30Ti20 HEA has been synthesized through the mechanical alloying technique. XRD analysis confirmed the formation of fcc and minor fraction of intermetallic R-phase at as synthesized state. The value of Ms and Hc for the synthesized HEA has found to be 75.16 emu/g and 12.92 Oe respectively. In order to investigate the thermal stability and phase transformation, the synthesized HEA was vacuum annealed at different temperatures. Annealing at different temperatures induces vital effect on the structural, microstructural and magnetic properties of Co35Cr5Fe10Ni30Ti20 HEA. The XRD patterns of the annealed (at 200°C, 700°C, 790°C, 870°C and 965°C) samples revealed the formation of fcc and minor intermetallic R-phase similar to the as synthesized sample, with change in the relative volume phase fraction of the fcc and R-phase. However, for 500°C annealed HEA, a new bcc phase evolved along with the primary fcc and R-phase. The microstructure of the low temperature annealed (at 200°C and 500°C) HEAs shows the similar morphology to the as synthesize HEA, whereas high temperature annealed (700°C to 965°C) HEAs revealed the formation of tiny spherical particles over the large grains. The value of Ms and Hc for the 200°C annealed HEA is found to be similar to the as synthesized HEA, while it increased (both Ms and Hc) for 500°C annealed HEA. However, a drastic change in the value of Hc has been observed for the high temperature annealed HEAs (700°C to 965°C). The value of Hc of the high temperature annealed HEAs decreased six times to the as synthesized HEA and found in the range of 1.66 to 1.95 Oe. In addition, the value of Ms has also changed after high temperature annealing. The 790°C annealed HEA exhibited excellent soft magnetic characteristics having high Ms (90.79emu/g) and low Hc (1.66 Oe) as compared to the presently studied other samples and also to the previously reported soft magnetic HEAs by others. The concluding reason behind the high value of Ms for annealed HEAs are a decrease in lattice parameter, i.e., improved magnetic interaction and a change in volume phase fraction of synthesized phases. However, the soft magnetic behavior of high temperature annealed HEA is attributed to the synergetic effect of the decrease in magneto crystalline anisotropy, particle size, and surface anisotropy. The value of Ms and Hc for the 790°C annealed HEA is comparable to some commercial soft magnets, such as Supermalloy, Ni-Zn ferrite, and Mn-Zn ferrite. Thus, the designed and developed Co35Cr5Fe10Ni30Ti20 HEA showed excellent soft magnetic characteristics even after annealing at high temperatures and may be further considered for industrial applications.
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