skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: New anisotropic MnBi permanent magnets by field-annealing of compacted melt-spun alloys modified with Mg and Sb

Abstract

A technique has been designed for manufacturing rare-earth-free MnBi-based magnets capable of filling the existing "gap" between the ferrite and rare-earth permanent magnets. Whereas the earlier approaches relied on sintering of fine and easily degrading single-crystal MnBi particles, the new method achieves refinement of the key α-MnBi phase through melt-spinning combined with appropriate alloying. Modification of the MnBi alloys with Mg and Sb generates a high-coercivity nanostructure of the metastable β' phase. A subsequent compaction at 150 °C produces fully dense materials while converting the β' phase into the stable α phase. Lastly, a short annealing at 265–300 °C in a magnetic field of 3 T increases the fraction of the α phase to 97–98% and aligns the c axes of the α crystallites. A maximum energy product (BH)max of 11.5 MGOe and an intrinsic coercivity Hc of 5.6 kOe have been obtained in a magnet with the nominal composition Mn50Bi46.5Mg3Sb0.5. Because the coercivity increases with temperature, the maximum energy product of this magnet is still as high as 8.9 MGOe at 175 °C. Increasing the Sb content to 1.5 at.% increases the Hc to 9.3 kOe, but at the same time inhibits the development of the texture thus decreasingmore » the (BH)max. The addition of Mg was found to increase the c lattice parameter of the α phase resulting in an unusually large ratio c/a ≈1.432.« less

Authors:
 [1];  [1];  [2]
  1. Univ. of Delaware, Newark, DE (United States)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Research Org.:
Univ. of Delaware, Newark, DE (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1561557
Alternate Identifier(s):
OSTI ID: 1562554
Grant/Contract Number:  
FG02-90ER45413
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Magnetism and Magnetic Materials
Additional Journal Information:
Journal Volume: 495; Journal Issue: C; Journal ID: ISSN 0304-8853
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; metals and alloys; permanent magnets; rapid-solidification; high magnetic fields; magnetic measurements; X-ray diffraction

Citation Formats

Gabay, Alexander M., Hadjipanayis, George C., and Cui, Jun. New anisotropic MnBi permanent magnets by field-annealing of compacted melt-spun alloys modified with Mg and Sb. United States: N. p., 2019. Web. doi:10.1016/j.jmmm.2019.165860.
Gabay, Alexander M., Hadjipanayis, George C., & Cui, Jun. New anisotropic MnBi permanent magnets by field-annealing of compacted melt-spun alloys modified with Mg and Sb. United States. doi:https://doi.org/10.1016/j.jmmm.2019.165860
Gabay, Alexander M., Hadjipanayis, George C., and Cui, Jun. Fri . "New anisotropic MnBi permanent magnets by field-annealing of compacted melt-spun alloys modified with Mg and Sb". United States. doi:https://doi.org/10.1016/j.jmmm.2019.165860. https://www.osti.gov/servlets/purl/1561557.
@article{osti_1561557,
title = {New anisotropic MnBi permanent magnets by field-annealing of compacted melt-spun alloys modified with Mg and Sb},
author = {Gabay, Alexander M. and Hadjipanayis, George C. and Cui, Jun},
abstractNote = {A technique has been designed for manufacturing rare-earth-free MnBi-based magnets capable of filling the existing "gap" between the ferrite and rare-earth permanent magnets. Whereas the earlier approaches relied on sintering of fine and easily degrading single-crystal MnBi particles, the new method achieves refinement of the key α-MnBi phase through melt-spinning combined with appropriate alloying. Modification of the MnBi alloys with Mg and Sb generates a high-coercivity nanostructure of the metastable β' phase. A subsequent compaction at 150 °C produces fully dense materials while converting the β' phase into the stable α phase. Lastly, a short annealing at 265–300 °C in a magnetic field of 3 T increases the fraction of the α phase to 97–98% and aligns the c axes of the α crystallites. A maximum energy product (BH)max of 11.5 MGOe and an intrinsic coercivity Hc of 5.6 kOe have been obtained in a magnet with the nominal composition Mn50Bi46.5Mg3Sb0.5. Because the coercivity increases with temperature, the maximum energy product of this magnet is still as high as 8.9 MGOe at 175 °C. Increasing the Sb content to 1.5 at.% increases the Hc to 9.3 kOe, but at the same time inhibits the development of the texture thus decreasing the (BH)max. The addition of Mg was found to increase the c lattice parameter of the α phase resulting in an unusually large ratio c/a ≈1.432.},
doi = {10.1016/j.jmmm.2019.165860},
journal = {Journal of Magnetism and Magnetic Materials},
number = C,
volume = 495,
place = {United States},
year = {2019},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

Save / Share:

Works referencing / citing this record:

High energy product of MnBi by field annealing and Sn alloying
journal, December 2019

  • Zhang, Wenyong; Balasubramanian, Balamurugan; Kharel, Parashu
  • APL Materials, Vol. 7, Issue 12
  • DOI: 10.1063/1.5128659