Wikipedia Deep Dive

Neodymium magnet

10 min read

The Strongest Magnets You've Never Thought About

Right now, within arm's reach, you probably have a dozen of them. They're in your phone. Your earbuds. Your laptop's hard drive. If you drove here, there are likely several kilograms of them in your car. And yet most people have never heard of neodymium magnets—the unassuming workhorses that made the modern world possible.

These small silvery objects are the strongest permanent magnets ever created. Not by a little bit. By a lot.

A neodymium magnet the size of a sugar cube can lift more than a thousand times its own weight. Compare that to the black ferrite magnets you stuck on your refrigerator as a kid, and neodymium magnets are eighteen times more powerful by volume. They're what happens when you take the rare earth element neodymium, mix it with iron and boron, and arrange the resulting crystals just so.

A Discovery Made Twice

In 1984, something unusual happened. Two companies on opposite sides of the Pacific—General Motors in the United States and Sumitomo Special Metals in Japan—independently invented the same thing at almost exactly the same time. Both discovered that an alloy of neodymium, iron, and boron, written chemically as Nd₂Fe₁₄B, could produce magnets of unprecedented strength.

This wasn't coincidence. It was necessity.

The magnets of that era were made from samarium and cobalt—another rare earth combination. They worked well enough, but cobalt was expensive and subject to supply disruptions. The global materials science community was hunting for alternatives, and two teams happened to find the same answer at the same moment.

The two companies took different paths with their discoveries. General Motors focused on a technique called melt-spinning, where molten metal is sprayed onto a rapidly spinning wheel to create thin ribbons studded with nanoscale magnetic grains. Sumitomo went with traditional sintering—grinding the alloy into powder, pressing it together, and heating it until it fuses into a solid block.

Both approaches work. Both are still used today. The melt-spun ribbons get mixed with plastic to create "bonded" magnets that can be injection-molded into complex shapes. The sintered blocks get cut and ground into precise forms. Your hard drive probably contains sintered magnets. Your power tools might use bonded ones.

Why They're So Strong

To understand what makes neodymium magnets special, you need to understand a bit about how magnetism works at the atomic level.

Every electron is a tiny magnet. When electrons pair up—one spinning clockwise, one counterclockwise—their magnetic fields cancel out. Only unpaired electrons contribute to a material's magnetism. Iron atoms have four unpaired electrons on average. Neodymium atoms have four as well, but they're arranged differently, in a way that makes them particularly effective at generating magnetic fields.

But raw magnetic strength isn't enough. A good permanent magnet also needs to stay magnetized. This property is called coercivity—the resistance to being demagnetized. And this is where the crystal structure of Nd₂Fe₁₄B becomes crucial.

The compound forms what crystallographers call a tetragonal structure. Picture a shoebox shape, but stretched in one direction. This asymmetry means the material strongly prefers to be magnetized along one specific axis. It really, really doesn't want to be magnetized in any other direction. When you try to demagnetize a neodymium magnet by applying an opposing field, the crystal lattice fights back.

During manufacturing, millions of these tiny crystals are aligned so their preferred axes all point the same way. The result is a magnet with both high magnetic strength and high resistance to losing that magnetism.

The Trade-Offs

Nothing in materials science comes free. Neodymium magnets have weaknesses.

Heat is their nemesis. As temperature rises, neodymium magnets lose their grip on magnetism. The technical term is that they have a relatively low Curie temperature—the point at which a magnet completely loses its permanent magnetization. For standard neodymium magnets, this happens around 320 degrees Celsius, or about 608 degrees Fahrenheit. Long before that, at temperatures as low as 100 degrees Celsius—the boiling point of water—they start to weaken significantly.

This matters enormously for applications like electric vehicle motors and wind turbines, where magnets operate in hot environments and need to maintain their strength. Engineers have developed modified alloys that include dysprosium or terbium—other rare earth elements—to boost heat resistance. But these additions make the magnets more expensive.

Corrosion is another problem. Sintered neodymium magnets are particularly vulnerable to moisture and air, which can attack the boundaries between the microscopic crystal grains. An unprotected magnet can literally crumble into powder over time. That's why nearly all commercial neodymium magnets come with protective coatings—usually nickel, zinc, or sometimes epoxy.

The Grading System

If you've ever shopped for neodymium magnets, you've encountered cryptic codes like N52 or N42SH. These aren't arbitrary. They're a standardized grading system that tells you exactly what you're getting.

The number indicates maximum energy product—essentially, how much magnetic energy the magnet can store per unit volume. N28 is relatively weak. N55 is among the strongest commercially available. The theoretical maximum is N64, though no one has achieved that yet.

The letters after the number indicate temperature tolerance. No letter means standard grade, good up to about 80 degrees Celsius. The sequence runs through M, H, SH, UH, EH, and TH, with TH magnets surviving up to 230 degrees Celsius. Higher temperature grades contain those expensive dysprosium and terbium additions.

So N52 is a very strong magnet with standard temperature tolerance. N35TH is a moderately strong magnet that can handle extreme heat. The grade you need depends entirely on your application.

China's Dominance

Here's a geopolitical reality that keeps defense strategists awake at night: China controls more than 95 percent of global rare earth element production. It manufactures about 85 percent of the world's neodymium magnets. Every other country combined accounts for a sliver of the market.

This didn't happen by accident. China has vast rare earth deposits and made a strategic decision decades ago to dominate the supply chain. They mined aggressively. They invested in processing facilities. They built manufacturing capacity. Western countries, meanwhile, allowed their own rare earth industries to wither because Chinese production was cheaper.

Japan holds second place with about 7 percent of global production. Vietnam is expanding, with new factories coming online. The United States and Europe are trying to rebuild domestic capacity, driven by concerns about supply chain security for everything from smartphones to missile guidance systems.

The United States Department of Energy has funded research into neodymium substitutes through programs like REACT—Rare Earth Alternatives in Critical Technologies. So far, no replacement has matched neodymium's combination of strength, weight, and cost. The search continues.

The Recycling Frontier

If you can't mine rare earths competitively, perhaps you can reclaim them from old products. This idea has launched a small but growing industry in magnet recycling.

The challenge is that neodymium magnets are typically embedded in products—motors, hard drives, speakers—and mixed with other materials. Extracting them requires either disassembly or whole-product processing. Then the magnets themselves must be broken down and their rare earths recovered.

Several approaches are being tested. The simplest is direct reuse: grind old magnets into powder using a process called hydrogen decrepitation, then re-sinter that powder into new magnets. This works but often produces weaker magnets because the original grain structure is disrupted.

Hydrometallurgical methods dissolve magnets in acid, then use chemical separation to extract pure rare earth oxides. You get high-purity outputs but generate a lot of chemical waste.

Pyrometallurgical methods use high-temperature smelting to recover rare earth alloys. Energy-intensive, but robust.

A newer approach called SEEE—Selective Extraction, Evaporation, and Electrolysis—attempts to combine the best features of existing methods. Rare earths are selectively dissolved from magnet waste, concentrated by evaporation, and recovered as metals through electrolysis. The promise is lower chemical use and alloys that can go directly back into magnet production.

Pilot plants are operating in the United States, Europe, and Japan. One American startup, HyProMag USA, plans to open an industrial-scale recycling facility near Dallas–Fort Worth in 2027, processing about 750 tonnes of magnets annually. That's a drop in the bucket compared to the 220,000 tonnes produced globally each year, but it's a start.

Where You'll Find Them

Neodymium magnets are everywhere, usually invisibly.

In your computer, they move the read-write heads in your hard drive with nanometer precision, thousands of times per second. In your headphones and speakers, they convert electrical signals into the pressure waves you hear as music. In your phone, they provide haptic feedback—that subtle vibration when you tap the screen.

Electric vehicles are particularly magnet-hungry. Each Toyota Prius contains about one kilogram—2.2 pounds—of neodymium in its drive motors. Multiply that by millions of vehicles and you begin to understand the scale of demand.

Wind turbines present an interesting case. Some designs use neodymium magnets in their generators; these direct-drive turbines have fewer moving parts and require less maintenance. But many wind turbines use conventional generators with electromagnets instead of permanent magnets. Claims that the renewable energy transition will create catastrophic neodymium shortages often overlook this distinction.

Cordless power tools depend on neodymium magnets for their motors. So do the servomotors in robots, the stepper motors in 3D printers, and the actuators that move components in countless industrial machines. Magnetic door latches, security tags in retail stores, MRI machines, even some high-end jewelry clasps—neodymium magnets have infiltrated nearly every corner of modern technology.

The Physics You Can Hold

There's something almost unsettling about handling a powerful neodymium magnet for the first time. The invisible force field around it is tangible. Bring two magnets close together and they either snap together with surprising violence or push apart with eerie resistance. The abstract concept of magnetic fields becomes viscerally real.

That force comes from quantum mechanics, from the alignment of electron spins across trillions of atoms, from crystal structures engineered at the nanoscale. A neodymium magnet is physics made touchable.

It's also, increasingly, a geopolitical object. The rare earths it contains were mined somewhere, probably China. The refining and manufacturing likely happened in Asia. The supply chain stretches across oceans and through trade policies and between competing national interests. Every neodymium magnet carries this invisible history.

The compound itself—neodymium, iron, boron—contains no precious metals. Neodymium is actually fairly abundant in the Earth's crust, about as common as copper. The "rare" in rare earth refers to how difficult these elements are to extract and separate, not to their scarcity. Deposits exist around the world. The challenge is processing them economically and cleanly.

New extraction technologies, new recycling methods, new alloy formulations—the neodymium magnet industry continues to evolve. What was impossible in 1983 became commercial in 1986 and ubiquitous by 2000. What limitations exist today may not exist in a decade.

But for now, these small powerful objects remain essential, invisible, everywhere. The modern world runs on rare earth magnetism, whether we notice it or not.