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.
Norman 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.