Environment-friendly bulk Fe16N2 permanent magnet: Review and prospective

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10 Scopus citations

Abstract

α″-Fe16N2 had been viewed as a mystery material because of inconclusive arguments in the 1990s, including many controversial reports at two MMM conference symposia, and the topic was then largely dropped by the magnetic research community. The key controversies around this material have now been successfully addressed through our long and persistent efforts from 2002 to 2012, first reported in APS 2010 and then at INTERMAG 2012. Since then, α″-Fe16N2 has been picked up as one of the most promising rare-earth-free magnet candidates because of its use of environment-friendly raw materials, confirmed giant saturation magnetic flux density (2.9 T), and reasonably high magnetic anisotropy constant (1.8 MJ/m3). Its coercivity temperature coefficient (~0.4 Oe/°C) in the range of 27–152 °C is two orders of magnitude lower than that of commercial NdFeB magnets (e.g. N40 ~ −81.9 Oe/K). The iron nitride magnet is of great interest as a magnetic material for applications working at relatively low temperature (<150 °C) and not requesting high coercivity. These applications range from speaker magnets to magnets in hard disk drives, electrical motors, wind turbines, smart phones, audio devices, and other power generation machines. A perspective review on the synthesis of the bulk α″-Fe16N2 compound permanent magnet is presented here on the aspects of material processing and magnetic characterizations. Specifically, we introduce and discuss our efforts to prepare the bulk Fe16N2 compound permanent magnet by using four different approaches, including an ion implantation method, a nanoparticle based approach, a high-temperature nitridation method based on foils, wires, and melt-spun ribbons, and a low-temperature nitridation method based on foils and ribbons. With our recent progress and many on-going activities by researchers worldwide, we believe that the α″-Fe16N2 compound permanent magnet is in an accelerating stage to be an alternative environment-friendly magnet candidate.

Original languageEnglish (US)
Article number165962
JournalJournal of Magnetism and Magnetic Materials
DOIs
StateAccepted/In press - 2019

Bibliographical note

Funding Information:
This work was supported in part by the ARPA-E (Advanced Research Projects Agency-Energy) BCT Fe16N2 Magnet project under contract No. 0472-1595. Parts of this work were carried out using the Characterization Facility, which receives partial support from NSF through the NSF Minnesota MRSEC program under Award Number DMR-0819885. Dr. Jian-Ping Wang has equity and royalty interests in, and serves on the Board of Directors and the Scientific Advisory Board of, Niron Magnetics, Inc. a company involved in the commercialization of the FeN magnet. The University of Minnesota also has equity and royalty interests in Niron Magnetics, Inc. These interests have been reviewed and managed by the University of Minnesota in accordance with its Conflict of Interest policies. The author thank for the following collaborators: N. Ji, X. Liu, Y. Xu, Y. Wu, M. Yang, X. Zhang, J. Liu, Y. Jiang, A. Mehedi, B. Ma, G. Guo, F. Zhang, X. Hang, B. Wolf, C.S?nchez-Hanke, F.M.F. de Groot, Lawrence F.Allard, Edgar Lara-Curzio, M. Brady, E. Fu, Y. Wang, P.K. Suri, G.Kennedy, N.N. Thadhani, D.J.Flannigan, V.Dabade, R.James. S. Sankar, B. Chelluri, R. Orlando, V. Lauter, C. Bridges. S. Bennet. Dr. Y. Jiang, Dr. A. Mehidi, Mr. J. Liu, Dr. G. Guo and Prof. B. Ma helped prepare some figures of the manuscript. A special thank goes to Y. Jiang, J. Liu and G. Guo for the preparation of this manuscript.

Funding Information:
This work was supported in part by the ARPA-E ( involved in the commercialization of the FeN magnet. The University of Minnesota also has equity and royalty interests in Niron Magnetics, Inc. These interests have been reviewed and managed by the University of Minnesota in accordance with its Conflict of Interest policies. Advanced Research Projects Agency-Energy ) BCT Fe16N2 Magnet project under contract No. 0472-1595 . Parts of this work were carried out using the Characterization Facility, which receives partial support from NSF through the NSF Minnesota MRSEC program under Award Number DMR-0819885. Dr. Jian-Ping Wang has equity and royalty interests in, and serves on the Board of Directors and the Scientific Advisory Board of, Niron Magnetics, Inc., a company The author thank for the following collaborators: N. Ji, X. Liu, Y. Xu, Y. Wu, M. Yang, X. Zhang, J. Liu, Y. Jiang, A. Mehedi, B. Ma, G. Guo, F. Zhang, X. Hang, B. Wolf, C.Sánchez-Hanke, F.M.F. de Groot, Lawrence F.Allard, Edgar Lara-Curzio, M. Brady, E. Fu, Y. Wang, P.K. Suri, G.Kennedy, N.N. Thadhani, D.J.Flannigan, V.Dabade, R.James. S. Sankar, B. Chelluri, R. Orlando, V. Lauter, C. Bridges. S. Bennet. Dr. Y. Jiang, Dr. A. Mehidi, Mr. J. Liu, Dr. G. Guo and Prof. B. Ma helped prepare some figures of the manuscript. A special thank goes to Y. Jiang, J. Liu and G. Guo for the preparation of this manuscript. Appendix A

Keywords

  • Bulk iron nitride magnet
  • Iron nitride
  • Magnetic energy product
  • Permanent magnet
  • Rare-earth-free magnet
  • α″-FeN

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