Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets

Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets

1st Edition - October 24, 2017

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  • Author: John J. Croat
  • eBook ISBN: 9780081022269
  • Paperback ISBN: 9780081022252

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Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets details the basic properties of melt spun NdFeB materials and the entire manufacturing process for rapidly solidified NdFeB permanent magnets. It covers the manufacturing process from the commercial production of the melt spun or rapidly solidified powder, to the production and properties of both isotropic bonded Nd and hot deformed anisotropic NdFeB magnets. In addition, the book discusses the development and history of bonded rare earth transition metal magnets and the discovery of the NdFeB compound, also covering melt spun NdFeB alloys and detailing the magnetization process and spring exchange theory. The book goes over the production of melt spinning development, the operation of a melt spinner, the processing of melt spun powder, commercial grades of NdFeB magnetic powder and gas atomized NdFeB magnetic powders. Lastly, the book touches on the major application and design advantages of bonded Nd Magnets.

Key Features

  • Features a unique perspective as the author is not only the inventor of NdFeB magnetic powder, but also played a key role in developing many of the technologies covered
  • Provides a comprehensive look at the history, fundamental properties, production processes, design and applications of bonded NdFeB magnets
  • Includes discussion of the rare earth supply challenge, politics, and systems as it impacts bonded NdFeB magnets


Materials Science and Electrical Engineering researchers and engineers, post-docs and graduate students

Table of Contents

  • 1. The development of rare earth permanent magnets
    2. The Nd2Fe14B intermetallic compound
    3. The properties of melt-spun NdFeB alloys
    4. Production of rapidly solidified NdFeB magnetic powder
    5. Production and properties of bonded Nd magnets
    6. Hot-deformed NdFeB permanent magnets
    7. The production and properties of sintered Nd permanent magnets
    8. Major applications for rapidly solidified NdFeB permanent magnets

Product details

  • No. of pages: 382
  • Language: English
  • Copyright: © Woodhead Publishing 2017
  • Published: October 24, 2017
  • Imprint: Woodhead Publishing
  • eBook ISBN: 9780081022269
  • Paperback ISBN: 9780081022252

About the Author

John J. Croat

Dr. John J. Croat obtained a Ph.D. (1972) degree in Metallurgy from Iowa State University in 1972. Following graduation, he joined the Physics Department of the General Motors Research Laboratories, where he was involved primarily with the research and development of permanent magnet materials from rare earth-transition metal alloys. While there, he was instrumental in the discovery of rapidly solidified NdFeB magnetic powder and the development of bonded NdFeB magnets. He also played a key role in the development of the processes and equipment for manufacturing these materials. He received eleven patents in this area, including all of the US composition patents for NdFeB magnets. He has received a number of awards for this discovery including the 1885 Applications of Physics Prize awarded by the American Institute of Physics and the 1986 New Material Prize awarded by the American Physical Society. In 1994 he was the recipient of an Outstanding Engineering Achievement Award by the American Society of Metals. In 1984, he transferred to the Delco Remy Division of General Motors to help start the Magnequench business unit, which was formed to commercialize NdFeB magnets. Between 1984 and 1995 he held various positions at this company, including Chief Engineer, Sales Manager and, from 1991 to 1995, Managing Director of the business. In 1995, General Motors sold the Magnequench business to a group of international investors and he left the company. In 1997 Dr. Croat helped AMR Technologies create a new NdFeB magnetic powder business. This division was named Advanced Magnetic Materials (AMM) and produced rapidly solidified NdFeB magnetic powder at a manufacturing facility in Nakhonratchasima, Thailand. He served as President of this company until 2004 when AMR Technologies merged with Magnequench to form Neo Materials Technology. Since 2007 he has served as a consultant to the world-wide permanent magnet industry.

Affiliations and Expertise

Consultant, International Permanent Magnet Industry, Naples, Florida, USA

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