A Forgotten Figure in the Evolution of Rare Earth Permanent Magnets

Sun, Sep 13, 2009


A Forgotten Figure in the Evolution of Rare Earth Permanent Magnets

Whenever I read articles in the media on neodymium-based [Nd-Fe-B] permanent magnets, I’m always interested to see how much historical detail the writer includes on the subject. The majority of writers either make no mention at all of the origins of Nd-Fe-B, or will mention only that it was developed by General Motors in the early 1980s. Certainly, Croat et al at the General Motors Research Laboratories did develop rapidly-quenched melt-spun ribbons of Nd-Fe-B at that time. The more astute [and perhaps less US-centric] writers will also mention that Sumitomo of Japan also developed Nd-Fe-B alloys, via a different processing route, at around the same time. Sagawa et al at Sumitomo Special Metals, did indeed develop sintered Nd-Fe-B powders and reported them at around that time. However, there is a third player in the history of Nd-Fe-B, one whose work was pivotal to the development of these materials, but whose name is almost never mentioned these days in the context of rare earth permanent magnets.

NormanKoonNorman Koon was a senior researcher at the US Naval Research Laboratory when, in 1980, he and his colleague Badri Das completed work that was presented at the 1980 Magnetism & Magnetic Materials Conference, on rapidly-quenched alloys of terbium-based [Tb-Fe-B] magnetic alloys. Dr. Koon filed for [and subsequently obtained] the first US patent on the subject matter, and by 1981, he was working on Nd-Fe-B alloys. Of course, by this time, other groups including GM and Sumitomo were also working in this area, having seen the work that Dr. Koon had presented previously. In later years, there would be extensive patent litigation on these rare earth-based [RE-Fe-B] alloys, as various parties jostled to establish who owned what rights to the commercial successes that they would bring.

Other contributions from Dr. Koon and his team included magnetostrictive compounds such as Ho-Tb-Dy-Fe, research on crystal field effects in rare earth based Laves phase compounds and an understanding of spin dynamics of rare earth intermetallics.

Dr. Koon passed away in 1997 – an article on his work and life was published in the IEEE Transactions on Magnetics in May 1998, by his former colleagues.

GM’s Delco Remy Magnequench division [which was subsequently spun off], Sumitomo Special Metals, and others, went on to conduct extensive further research on Nd-Fe-B materials, which led to the evolution of high performance material grades of Nd-Fe-B perhaps undreamt of a quarter century ago… however, I think it’s fair to say that the work of Norman Koon was a vital part of that evolution, one that future article writers would do well to remember.

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Gareth is a Founding Principal at Technology Metals Research, LLC. He has expertise in a variety of magnetic materials, devices and applications, and their associated trends and challenges, particularly for renewable energy production. For more information check out his biography page. Don't forget to check out Terra Magnetica at Twitter too.

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3 Responses to “A Forgotten Figure in the Evolution of Rare Earth Permanent Magnets”

  1. Scott Masteller Says:

    I did work with Norm Koon or actually I worked in another group that competed with Norm on crystal growth in rare earth iron alloys for magnetostrictive transducers for sonar systems. It is interesting that there was a rivalry. The group I was with focussed on the heavy rare earths like holmium and terbium, leaving the field open to Norm to look at the lighter rare earth iron compounds. The heavy rare earths lead to the development of Terfenol, certainly a useful if not widely used material, while the light rare earths led to Nd-B-Fe.

  2. Stan Says:

    Norm was the editor for one of my papers. He certainly was a gentleman.

    I have heard some people say that Norm may have been the first to really understand that Nd2Fe14B was the compound of interest. While GM and Sumitomo (now Hitachi) certainly won the race to the Patent Office, Norm may have been the first man on the mountain.

    Another person of interest for the early days of NdFeB was Joe Becker from GE. Joe did some wonderful work with SmCo5 single grains, giving some insight on the domain wall motion mechanism. He also gave a talk on rapid quenched rare earth iron compounds at the famous MMM conference in Pittsburgh in the fall of 1983, along with Koon and the groups from GM and Sumitomo. He may have been close to the truth, too, but sadly he passed away the next year.

    Both were humble men, true scholars, at a time when being humble was not popular.

  3. Karen Hoofnagle (Koon) Says:

    Norman Koon was my dad and I found this googling his name, which I do from time to time. It’s nice to see him remembered kindly not just for his work, but (thanks Stan) for his humility and scholarship.

    I’m no judge of his physics scholarship, but I can say that in all my adult life I’ve never yet met another academic who was as well suited to be happy in his working environment. Dad certainly liked having done work that turned out to be important, but he was completely happy to just get to *do* research and had an exuberant love of both his work and his colleagues. Even into my 20s when we talked about more complex things I never heard him speak disparagingly of a colleague. Or really of anyone now I think of it.

    Anyhow, thanks for remembering him.