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The Magnet That Made the Trendy World


For sheer drama and resonance, few tech breakthroughs can match the invention of the neodymium-iron-boron everlasting magnet within the early Eighties. It’s one of many nice tales of company intrigue: Common Motors within the US and Sumitomo in Japan independently conceived the know-how, after which labored in secret, racing to commercialize the know-how, and with out even being conscious of the opposite’s efforts. The 2 challenge leaders—Masato Sagawa of Sumitomo and John Croat of GM—stunned one another by asserting their outcomes on the identical convention in Pittsburgh in 1983.

Up for grabs was a market probably price billions of {dollars}. One of the best everlasting magnets on the time, samarium-cobalt, had been robust and dependable however costly. They had been utilized in electrical motors, turbines, audio audio system, hard-disk drives, and different high-volume merchandise. At present, some 95 p.c of everlasting magnets are neodymium-iron-boron. The worldwide marketplace for these magnets is anticipated to achieve $20 billion a yr inside a few years, as the auto trade shifts in the direction of electrical autos and as utilities flip more and more to wind generators to satisfy rising demand.

IEEE just lately honored Sagawa and Croat by awarding them its Medal for Environmental and Security Applied sciences on the 2022 Imaginative and prescient, Innovation, and Challenges Summit. IEEE Spectrum spoke with the 2 inventors, together with an hourlong interview with each of them (solely the second time the 2 have been interviewed collectively). They revealed their causes for zeroing in on the rare-earth aspect neodymium, the foremost challenges they confronted in making a industrial magnet out of it, the extraordinary intellectual-property deal that allowed each GM and Sumitomo to market their magnets worldwide, and their opinions on whether or not there’ll ever be a profitable everlasting magnet that doesn’t use rare-earth parts.

John Croat and Masato Sagawa on…

• How they settled on neodymium, iron, and boron

• The most important hurdles to producing a commercially viable magnet

• The low-key deal struck between GM and Sumitomo to permit international advertising of their magnets

• Why there’ll by no means be a profitable everlasting magnet that doesn’t use rare-earth parts

You had been attempting to make a less expensive magnet, as I perceive it. You were not even essentially attempting to make a stronger one, though that turned out to be the case. What made you assume you could possibly make a less expensive magnet?

A white-haired man in a red tie appears mildly bemusedJohn Croat

John Croat: Effectively, the issue with samarium-cobalt… they had been a wonderful magnet. That they had good temperature properties. You have in all probability heard the phrase that rare-earths aren’t actually that uncommon, however samarium is among the extra uncommon ones. It constitutes solely about 0.8 p.c of the composition of the ores which are sometimes exploited as we speak for rare-earths. So it was a reasonably costly rare-earth. And, after all, cobalt was very costly. Throughout my early years at Common Motors Analysis Labs, there was a warfare in Central African Zaire [now known as the Democratic Republic of the Congo], which is a giant cobalt provider. And the value of cobalt went as much as one thing like $45 a kilogram. Bear in mind, this was within the Seventies, so it mainly stopped our analysis on samarium-cobalt magnets.

Masato, what do you bear in mind? What do you recall of the state of the permanent-magnet market and know-how within the Seventies in Japan?

A white-haired man smiles at the cameraMasato Sagawa

Masato Sagawa: I joined Fujitsu in 1972, in order that’s in the identical age as with John. And I used to be given from the corporate to enhance the samarium-cobalt magnet to enhance the mechanical power. However I puzzled why there isn’t any iron compound. Iron is less expensive and way more [available] than cobalt, and iron has larger magnetic second than cobalt. So if I can produce rare-earth iron magnets, I assumed I’ll have larger magnetic strengths and far decrease price. So I began to analysis the samarium-cobalt—or rare-earth iron compound. Nevertheless it’s an official topic in Fujitsu. And I labored onerous on the samarium-cobalt. And I succeeded within the growth of samarium-cobalt magnet with excessive power. And I requested the corporate to work on a rare-earth iron compound everlasting magnet. However I used to be not allowed. However I had an concept. Uncommon-earth, iron and, I feel, a small quantity of additive parts like some carbon or boron, that are recognized to have a really small atomic diameter. I studied the rare-earth, iron, boron or rare-earth, iron, carbon. So underground, I did this analysis for a number of years. And I reached this neodymium-boron a number of years later. It was in 1982.

What was it that made you give attention to neodymium, iron, and boron? Why these?

Croat: Effectively, after all, when samarium-cobalt magnets had been developed, everybody on this discipline considered growing a rare-earth-iron magnet as a result of iron is nearly free in comparison with cobalt. Now, when it comes to the uncommon earths, as I stated, uncommon earths will not be actually that uncommon. The sunshine uncommon earths lanthanum, cerium, praseodymium, and neodymium represent about 90 p.c of the composition of a typical rare-earth deposit…. So we knew in the beginning that if we needed to make an economically viable magnet, each Dr. Sagawa and I noticed that we needed to make the everlasting magnet from one among these 4 uncommon earths: lanthanum, cerium, neodymium, or praseodymium. The issue with lanthanum and cerium, as you understand, the lanthanides are shaped by filling the 4F electrons within the 4F collection. Nonetheless, lanthanum and cerium, the 2 most plentiful rare-earths, had no 4F electrons. And we knew by this time, primarily based on the work with samarium-cobalt magnets, that one of many issues that you simply needed to have was these 4F electrons to provide the coercivity for the fabric.

Are you able to give us a fast definition of coercivity?

Croat:Coercivity is the resistance to demagnetization. In a everlasting magnet, as you say, the moments are all aligned parallel. For those who put a magnetic discipline within the reverse path, the coercivity will resist the magnet flipping into the wrong way.

We knew that we needed iron as an alternative of cobalt…. And each of us set out with the intention of constructing a rare-earth iron everlasting magnet from neodymium or praseodymium. The issue was that there was no intermetallic compounds obtainable. Not like on this rare-earth cobalt section diagram—there was numerous attention-grabbing intermetallic compounds—the rare-earth-iron section diagrams don’t comprise appropriate usable intermetallic compounds.

In plain language, what’s an intermetallic section, and why is it essential?

Croat: An intermetallic compound or an intermetallic section is a section with a hard and fast ratio of the elements. Like, terbium-iron two has one terbium and two irons. And it sits on a crystal lattice in very particular websites on the lattice. You must have that. That is one of many quintessential necessities for any rare-earth transition-metal everlasting magnet.

It offers the construction and stability you want or the reproducibility?

Croat: All of that. In different phrases, it is the factor that holds the magnetic second in place within the construction. You must have this crystal construction.

So what was the answer?

Croat: The truth that there was no intermetallic compound was a baffling downside for a while. However then, in 1976, I and a few colleagues noticed a paper by Artwork Clark. He was working on the Naval Floor Weapons Laboratory. He had taken a sputtered pattern of terbium iron two [TbFe2] and annealed it at more and more larger temperatures. And at about 350 levels centigrade, the coercivity shot as much as about three and a half kilo oersted. And we surmised, and I feel appropriately on the time, that what had occurred was that throughout the crystallization course of, a metastable section had shaped. This was thrilling as a result of that is the primary time anybody had ever developed a coercivity in a rare-earth iron materials. It was additionally thrilling due to the truth that TbFe2 is a cubic materials. And a cubic materials shouldn’t develop coercivity. You must have a crystal construction with a uniaxial crystal lattice, like hexagonal, rhombohedral, or tetragonal.

And so I began out with that thesis: to create magnetically onerous metastable phases which are sensible for everlasting magnets. And through the use of fast solidification, I began making melt-spun supplies and crystallizing them. And it labored very nicely. I had developed very excessive coercivities instantly. The issue with these supplies had been that they had been all unstable. I began to warmth them up at about 450 levels C, and they might decompose into their equilibrium construction, and the coercivity would go away. So I started so as to add issues to see if I might make them extra secure. And one of many issues I added was boron. And someday I discovered that after I heated my pattern up containing boron, it didn’t decompose into its equilibrium construction. And so I knew that I had found a ternary neodymium-iron-boron intermetallic section, a really attention-grabbing, technically essential intermetallic section. And it seems that Masato found the identical one [laughter].

Sagawa-san, you talked about that you simply had been fascinated about a sintering course of which was much like the method that was then getting used to fabricate samarium-cobalt magnets…. Whenever you had been engaged on a solution to make neodymium-iron-boron magnets utilizing sintering, did you encounter particular challenges that had been tough that took lots of effort to resolve?

Sagawa: I used to be not in a position to give coercivity to the neodymium-iron-boron alloy. And I attempted many processes. However the price of sintering is nice as a result of to provide coercivity to the alloy, it’s important to make a mobile construction within the alloy. So to supply mobile construction, the sintering is an excellent manner as a result of first, you make single-crystal or powder and also you align the powder after which sintering. And through sintering, you type mechanically mobile construction.

So I attempted to type mobile construction. I examined many, many sorts of parts ranging from copper. Copper is used within the case of samarium-cobalt magnets. And ranging from copper, I examined many, many additive parts virtually all through the periodic desk. However I used to be not in a position to give coercivity by making extra parts. And finally, I discovered a superb additive aspect. It is not one other aspect—it is neodymium itself. Further neodymium offers dwelling to mobile construction forming a grand boundary space across the neodymium-iron-boron particles. So I succeeded in giving coercivity to the neodymium-iron-boron by sintering and a neodymium-rich composition. And I succeeded in growing a neodymium-boron sintered magnet with record-high BH most [a measure of the maximum magnetic energy that can be stored in a magnet] on the planet. It was in 1982.

This work is generally taking place within the late Seventies, early Eighties. You’re each engaged on virtually the identical downside on completely different sides of the world. Sagawa-san, when did you first discover out that Common Motors was additionally engaged on the identical problem that you simply had been engaged on?

Two men stand in a conference room behind a podium.Masato Sagawa of Sumitomo (left) introduced the invention of a revolutionary neodymium-iron-boron everlasting magnet at a convention in Pittsburgh, Penn., in November, 1983. On the identical assembly, John Croat of Common Motors (proper)introduced the invention of a magnet utilizing the very same parts.Masato Sagawa

Sagawa: It was after I made the primary presentation on the MMM Convention, Magnetism and Magnetic Materials Convention, held in Pittsburgh in 1983.

Croat: November 1983.

Sagawa: November, 1983. On the identical convention, John Croat and his group introduced a paper on the identical neodymium-boron alloy magnets.

So for years, you each had been engaged on this downside, attacking the identical downside. And also you each came upon in regards to the different effort on the identical convention in Pittsburgh in 1983?

Croat: Sure.

That is astounding. Did you speak to one another at that convention? Did you get collectively and say something to one another?

Croat: I feel we launched ourselves to one another, however I do not bear in mind way more than that.

What do you recall, Sagawa-san? Do you recall any dialog with John at that assembly?

Sagawa: I do not forget that I noticed John, however I do not bear in mind if we talked collectively or not.

Croat: I feel it will have been logical if we did, however I can not bear in mind it. We in all probability thought of ourselves opponents [laughter].

You each got here up with unbiased means of producing. Common Motors got here up with a way known as melt-spinning, and Sumitomo’s was a sintering course of. That they had completely different traits. The sintered magnets appear to have extra structural power or resilience. The GM magnets will be produced extra inexpensively. They each discovered massive market purposes, considerably completely different however nonetheless massive makes use of. John, why do not you’re taking a crack in simply explaining what their market niches grew to become and nonetheless are to at the present time?

Croat: Sure. The quickly solidified supplies are isotropic. And throughout the fast solidification course of, you type a magnetic powder. That powder is mixed with an epoxy and made right into a magnet. Nevertheless it turned out that these magnets had been excellent for making small ring magnets that go into micro motors like spindle motors for onerous disk drives or CD-ROMs or for stepper motors. In order that has—

For robots.

Croat: For robots and issues of that nature, servo motors for robots, but additionally spindle and stepper motors for numerous purposes. And that has been the first marketplace for these bonded magnets as a result of making a thin-wall ring magnet by the sintering course of could be very tough. They have an inclination to crack and break aside. However in distinction, the sintered-magnet market, which is way greater really than the bonded-magnet market, has been used primarily for greater motors, wind-turbine turbines, MRIs. Many of the electric-vehicle motors are sintered magnets. So once more, many of the market is motors. However the market is larger for the sintered-magnet market than it’s for the bonded-magnet market. However there are two distinctly completely different markets typically.

Sagawa: I feel some of the essential purposes of the neodymium-iron-boron magnet is the hard-disk drive. If the neodymium-boron was not discovered, it will have been tough to miniaturize the hard-disk drive. Earlier than the looks of the neodymium-boron magnet, the hard-disk drive was very massive. It was tough to carry by one individual, 10 kilo or 20 kilogram or so. Now it turns into very small. And that is due to the invention of neodymium-boron sintered magnet which is used within the actuator motor. And in addition, the bonded-magnet neodymium is used within the spindle motor to rotate the onerous disk. This was an important invention for the beginning of our IT society.

An open hard driveLaborious-disk drives comprise a number of neodymium everlasting magnets. There’s one within the spindle motor that rotates the disk, and sometimes two others within the read-write arm, also referred to as the actuator arm (the triangular formed construction within the picture) that detects and writes knowledge on the disk.Getty Photographs

You had little or no contact with one another till this assembly in Pittsburgh in 1983, by which period you’d already established all of your mental property. And but there was a long-running—nicely, not that long-running, however a patent case between Common Motors and Sumitomo. John, are you able to begin off and inform us a little bit bit about what occurred there?

Croat: Sure. I suppose we did not point out it, however each Sumitomo and Common Motors filed patents shortly after the invention of this materials, which turned out to be early 1982, apparently inside weeks of one another. Nevertheless it seems, due to patent legislation, the way in which patent legislation is written, Common Motors ended up with the patents in North America, and Sumitomo ended up with the patents for the composition neodymium-iron-boron, in Japan and Europe. Common Motors had the neodymium-iron-boron composition in North America. This meant that neither firm might market worldwide, and so they had to market worldwide to be economically viable. So they really had a dispute, after all. I do not know if they really sued one another. However anyway, they’d a negotiation. And I bear in mind being a part of these negotiations the place we ended up with an settlement the place we cross-licensed one another, which allowed each firms to market the fabric worldwide—manufacture and market the fabric worldwide.

However you could possibly solely manufacture and market your kind of fabric, which, in your case, was this melt-spun, fast—

Croat: Solidification, melt-spinning.

Solidification. And Sumitomo had the sintering worldwide, North America, Asia, Europe, in every single place.

Croat: It turned out it was primarily based on the particle dimension of the fabric. Sumitomo had the rights to fabricate magnets with a particle dimension larger than one micron, Common Motors lower than one micron.

Sagawa: Oh, you bear in mind!

Croat: Sure. [Both laugh]

Proper now, after all, there’s lots of controversy over the truth that an unlimited quantity of the world’s marketplace for rare-earth parts is managed by China, the mining, the manufacturing, and so forth. So many nations, notably in Europe and North America, need to broaden their base of suppliers for rare-earths. However on the identical time, there’s this present marketplace for these magnets. So is that this having an impact of any type on the longer term instructions of R&D in everlasting magnets?

Croat: I’m not shut sufficient to the R&D to know what is going on on, however I feel there was no change. Persons are nonetheless fascinated about making everlasting magnets primarily containing a rare-earth.

I do not see how they’re ever going to get the rare-earth out of a rare-earth transition metallic magnet and make a superb high-performance magnet. So the rare-earth provide downside goes to proceed and can perhaps even develop sooner or later as the marketplace for these magnets grows. And I feel the one manner that they’ll overcome that’s that Japan and Korea and Western Europe and North America should have some form of authorities assist to determine a rare-earth market outdoors of [China]. There are lots of nations which have rare-earths. India, for instance, has rare-earths. Australia, Canada have rare-earths. United States, after all, has a number of massive deposits. However what occurred was, after all, the Chinese language decreased the value to the purpose again within the Nineteen Nineties and drove everyone else out of enterprise. So by some means, some political will must be put forth to vary the dynamics of the rare-earth market as we speak.

Sagawa: I feel it is inconceivable to supply high-grade magnet with out rare-earths. It is concluded just lately. There are very energetic analysis on an iron-nickel compound; it was promising. It has high-saturation magnetization and a really excessive anisotropy discipline. However I feel, in current analysis in Japan, it was concluded [that] it is inconceivable to supply high-performance everlasting magnet from this iron-nickel compound. And that is the final analysis topic on the rare-earth-free compound consisting of solely 3D [orbital] -electron parts, iron-cobalt-nickel.

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