Design and development of Co35Cr5Fe20−xNi20+xTi20 High Entropy Alloy with excellent magnetic softness

• Published in: Journal of alloys and compounds 2021-12, Vol.889, p.161773, Article 161773
• Main Authors: Mishra, Rajesh K., Kumari, Priyanka, Gupta, Amit K., Shahi, Rohit R.
• Format: Article
• Language: English
• Subjects: Annealing; Coercivity; Extreme values; Heat treatment; High Entropy Alloy; High entropy alloys; Magnetic materials; Magnetic properties; Materials science; Mechanical alloying; Nanocrystalline; Soft magnetic material; Softness; Synthesis
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.161773

•The influence of Fe/Ni content on structural and magnetic behavior is studied for Co35Cr5Fe20−xNi20+xTi20 HEAs.•The mixture of the fcc, and a minor R-phase are evolved for all the synthesized HEAs.•The coercivity decreased more than five times to the initial value after the heat treatment.•Annealed Co35Cr5Fe10Ni30Ti20 HEA exhibits excellent soft magnetic properties Ms = 78.01 emu/g and extremely low Hc = 1.7 Oe•The found coercivity is the lowest value of coercivity reported so far for the case of magnetic HEAs. The design and development of excellent soft magnetic materials are fascinating research areas in materials science. A series of Co35Cr5Fe20−xNi20+xTi20 (x = 5, 10, 15) High Entropy Alloys (HEAs) were synthesized through mechanical alloying (MA) technique and heat-treated at two different temperatures at 200 °C and 700 °C for 2 h. The XRD analysis confirmed that the HEAs comprised of face-centered cubic (fcc) phase and a minor fraction of an intermetallic R-phase at as-synthesized and annealed state. SEM-EDS observation confirmed the homogeneous compositional distribution and showed that after annealing at 700 °C, tiny spherical particles precipitated over the large grains. The synthesized HEAs showed soft magnetic behavior with low coercivity (12–16 Oe). However, the coercivity decreased more than five times to the initial value after the annealing at 700 °C. Co35Cr5Fe10Ni30Ti20 HEA annealed at 700 °C shows excellent soft magnetic properties with a high value of Ms (78.01 emu/g) and an extremely low value of Hc (1.7 Oe). The found value of the coercivity is the lowest value of the coercivity reported so far for the case of magnetic CoCrFeNiTi based HEAs. In addition, the present work provides a novel design strategy for the development of magnetic HEAs with excellent magnetic softness.