Rapidly Solidified Neodymium-Iron-Boron Permanent Magnets

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.

• 1. The development of rare earth permanent magnets2. The Nd2Fe14B intermetallic compound3. The properties of melt-spun NdFeB alloys4. Production of rapidly solidified NdFeB magnetic powder5. Production and properties of bonded Nd magnets6. Hot-deformed NdFeB permanent magnets7. The production and properties of sintered Nd permanent magnets8. Major applications for rapidly solidified NdFeB permanent magnets