History of Rare Earth Magnets

In the aspect of bulk magnetic materials, there are three generations of rare earth permanent magnets (REPM) (see the historic plot in PM history page):

  1. SmCo5 Magnets: 1966-1970s; 
  2. Sm2Co17 based Magnets: 1970s; 
  3. Nd2Fe14B based Magnets : Early 1980s


In 1966, Dr. Karl J. Strnat and his colleagues at the U.S. Air Force Materials Laboratory at Wright-Patterson Air Force Base discovered the extremely high magnetocrystalline anisotropy in RE-Co alloys, which led to the development of high energy product (18-25 MGOe) of the Samarium-Cobalt (SmCo5) compound. This milestone was named as one of the 100 Greatest Moments in Materials and Engineering History around the world. (read more). 

In 1972, collaborated with other research laboratories around the world, Dr. Karl J Strnat and Dr. Alden Ray of University of Dayton developed a higher energy product Samarium-Cobalt (Sm2Co17) compound with additions of Fe, Cu, and Zr. The energy product of Sm2Co17 magnets is as high as 33 MGOe.  Sm-Co magnets have excellent thermal stability and can be used at temperatures as high as 550°C. 

In 1982, Nd-Fe-B magnets were invented independently by Dr. Masato Sagawa of Sumitomo as sintered Nd-Fe-B magnets with full density,
and by Dr. John Croat of GM as melt-spun Nd-Fe-B for bonded magnets or hot-processed magnets. The highest energy product of Nd-Fe-B magnets was reported at 59.5 MGOe. Nd-Fe-B industry has become the largest magnet industry since early 1990’s.  Around the world in 2012, about 90,000 tons of sintered Nd-Fe-B magnets were made, and about 8,000 tons of bonded NdFeB magnets were made, according to our  information. 

Dr. Masato Sagawa was awarded with the Japan Prize  in Jan 25, 2012 for his discovery of Nd-Fe-B magnets and his endless effort in pursuit of the Ultimate Magnets.

In 1990, Sm2Fe17N3 magnets were signaled by Dr. Coey and Dr. Sun, and developed independently by Iriyama, Kobayashi and coworkers in 1992 [1]. The compound has high anisotropy, and it decomposes at T > 500°C. The magnets can be used as powder form or bonded magnets. 

In the past 30 years, the powerful magnets have tremendous impact on human’s life. Today the rare earth magnets are essential components in modern technologies, used in many electric and electronic devices from computers, appliances, to medical equipment. In recent years the emergent applications in renewable energy have come to the landscape, including the large-scale applications in hybrid /electrical vehicles and wind turbines.



Picture

Dr. K Strnat (R), Dr. A.E.Ray (M)
and Prof. H. Meldrum (L)

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Dr. M. Sagawa and Dr. K. Strnat in 1983
  Dr. M. Sagawa 
Dr. J. Croat

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TWT with Sm-Co magnet assembly made by EEC [2]

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Nickel plated Nd-Fe-B magnet on a bracket from a hard drive [3]

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With EEC SmCo magnets in the TWT amplifiers, NASA Voyager 1 has been operating for 35 years [4]

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2.5-megawatt wind turbines using NdFeB magnets made by Goldwind, China [5]

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Toyota hybrid car made using electric motor with NdFeB magnet (see footnote for citation) [6]
[1] Rare-Earth Iron Permanent Magnets, Edited by J.M.D. Coey, p. 370
[2] http://www.electronenergy.com/applications/traveling-wave-tubes-klystrons-magnetrons.htm
[3] http://en.wikipedia.org/wiki/Neodymium_magnet
[4] http://www.electronenergy.com/lifetime-guarantee.htm
[5] http://www.evwind.es/2012/09/14/goldwind-to-supply-panama-wind-farm-with-wind-turbines/23387
[6] Photo used under Creative Commons from Toyota Motor Europe
[7] http://www.japanprize.jp/data/photos2012/20120425_presentation_ceremony_select/images/_D3S0321.jpg
 
International Workshop on Rare-Earth Permanent Magnets 
and Their Applications  (REPM)
      The 1st in this series of workshops took place in 1974 in Dayton, OH, USA, and it has been followed by 22 similar, highly regarded conferences held all over the world. The history of the REPM Workshops parallels the development of rare-earth magnets as commercial products. Over the past half century, rare-earth magnets have progressed from being the subject of basic research in the laboratory to becoming a major global industry. Today, these magnets are being manufactured on a huge scale and find uses in many industries and countless high-technology products. Rare-earth magnets are playing an increasing role in our daily lives with their myriad applications.

The list below show the last four Workshops held in four countries, as well as the one that will be held in 2018:

REPM’10,  Sept. 2010, Bled, Slovenia,    http://nano.ijs.si/repm10.htm   
REPM’12, Sept. 2012, Nagasaki, Japan,
http://www.sntt.or.jp/REPM2012/index_.php?id=home 
REPM’14:  Aug. 2014, Annapolis, US

REPM’16:  Aug. 2016, Darmstadt, Germany
http://www.repm2016.tu-darmstadt.de/repm_2016/index.en.jsp

REPM’18:  Aug. 2018, Beijing, China
http://www.repm2018.org/