Development of rare-earth-free bulk magnets with energy product up to 12 MGOe in field annealed Mn–Bi–Mg–In–Sb alloys

Journal Article · Fri Jan 03 00:00:00 EST 2020 · Journal of Alloys and Compounds

DOI:https://doi.org/10.1016/j.jallcom.2020.153663· OSTI ID:1580855

Gabay, Alexander M.  ^[1]; Hadjipanayis, George C. ^[1]; Cui, Jun  ^[2]

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1. Univ. of Delaware, Newark, DE (United States)
2. Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States)

A treatment consisting of annealing in a moderately strong, ≤30 kOe, magnetic field was applied to arc-melted ingots and compacted melt-spun alloys with composition Mn₅₀Bi_50-x-y-zMg_xIn_ySb_z. The high degree of texture of the magnetic α phase induced with annealing of the ingot samples (except the Mn–Bi–Sb one) allowed for accurate determination of the phase anisotropy field. Alloying was found to increase the anisotropy field from 45 kOe in the Mn₅₀Bi₅₀ alloy to 65 kOe in the Mn₅₀Bi₄₅Mg₃In_0.5Sb_1.5 alloy. In the compacted melt-spun alloys subjected to field annealing, a higher degree of texture could be achieved after compaction which had involved less heating, when a smaller fraction of the metastable β' phase had been converted into the α phase; compaction at room temperature allowed for the highest degree of texture in the Mn₅₀Bi₄₅Mg₃In_0.5Sb_1.5 magnet. The addition of indium was found to decrease the solidus temperatures of the alloys, facilitating the development of the α phase during the field annealing and modifying the properties of the resulting magnets. Introduction of indium resulted in a higher coercivity H_c of the Mn–Bi–Mg–In magnets and in a better texture of the Mn–Bi–Mg–Sn–In magnets. The former effect allowed, in particular, for a viable maximum energy product (BH)_max of 10 MGOe to be developed in the Mn₅₀Bi_46.5Mg₃In_0.5 magnet through annealing in a relatively low field of 15 kOe, whereas the latter effect allowed for an excellent combination of (BH)_max = 11.6 MGOe and H_c = 8.5 kOe in the Mn₅₀Bi₄₅Mg₃In_0.5Sb_1.5 magnet. The highest (BH)_max of 12 MGOe was realized in the Mn₅₀Bi₄₆Mg₃In_0.5Sb_0.5 magnet.

• Research Organization: Univ. of Delaware, Newark, DE (United States); Iowa State Univ., Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-90ER45413; EE0007794
• OSTI ID: 1580855
• Alternate ID(s): OSTI ID: 1778268; OSTI ID: 1864015
• Journal Information: Journal of Alloys and Compounds, Vol. 822; ISSN 0925-8388
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
permanent magnets
rapid-solidification
sintering
magnetic measurements
thermal analysis
X-ray diffraction
MnBi