Tag: permanent magnets

  • Samarium: The Cold War Magnet the Pentagon Can’t Get Anymore

    Samarium cobalt magnets were the original high-performance permanent magnet — the technology that made precision-guided missiles, satellite attitude control, and miniaturized radar possible during the 1970s and 1980s. Then neodymium-iron-boron magnets arrived in 1984, offered stronger fields at lower cost, and samarium cobalt was demoted to a niche material for applications where NdFeB couldn’t survive: environments above 300°C, corrosive atmospheres, radiation exposure, and systems where demagnetization from temperature cycling would be mission-fatal. Fighter jet engine accessories. Missile fin actuators. Traveling wave tubes in military radar. Naval sonar transducers. Satellite reaction wheels. The applications are small in volume and enormous in consequence. Samarium cobalt accounts for less than 2% of global permanent magnet production. It is irreplaceable in systems where failure means a missile doesn’t steer, a radar doesn’t function, or a submarine doesn’t hear. And as of April 4, 2025, China placed samarium — along with terbium, dysprosium, and four other rare earths — under export controls that have effectively halted the reliable flow of SmCo magnets to Western defense contractors.

    What makes SmCo different

    SmCo magnets come in two grades: SmCo5 (samarium-cobalt 1:5) and Sm₂Co₁₇ (samarium-cobalt 2:17). Both offer thermal stability that NdFeB cannot match. NdFeB magnets start losing their magnetic properties above 80°C without terbium or dysprosium additives, and even with additives, they max out around 200°C. SmCo magnets operate at 250-350°C with no additives and no performance degradation. They resist corrosion without the nickel-copper-nickel plating that NdFeB requires. They’re immune to radiation damage at levels that would demagnetize NdFeB. The tradeoff is energy density — NdFeB magnets produce stronger fields per unit volume — and cost, because both samarium and cobalt are expensive relative to neodymium and iron.

    For commercial EV motors and wind turbines, NdFeB wins on performance per dollar. For a missile guidance system operating in an engine bay at 300°C where corrosion resistance matters and magnetic stability is non-negotiable, SmCo is the only option. That division of labor — NdFeB for the clean-energy economy, SmCo for the defense industrial base — is what makes the April 2025 export controls particularly consequential. The Battlefields of the Future course covers how modern weapons systems depend on precision components. SmCo magnets are among the most precision-critical and least substitutable of those components.

    The supply chain that doesn’t exist outside China

    China refines approximately 90% of the world’s samarium. SmCo magnet manufacturing is concentrated in China because the entire rare earth separation and metal refining supply chain is concentrated in China. When Arnold Magnetic Technologies — one of the few Western SmCo manufacturers, with facilities in the United States, Switzerland, and Thailand — received the April 4 export control announcement, their Chief Commercial Officer noted they had already secured more than a year’s worth of samarium metal inventory. Arnold has since built a non-Chinese samarium and cobalt supply chain to feed its Swiss and Thai manufacturing. That makes Arnold an exception. Most Western magnet buyers are not exceptions.

    The Western alternatives that exist are narrower than the headlines suggest. Lynas Rare Earths announced in March 2026 that it had produced the first separated samarium oxide at its Malaysian facility — the first non-Chinese samarium separation in commercial history. The milestone is genuine but the scale is small. Solvay holds a legacy stockpile of roughly 200 tonnes of samarium nitrate in France — material that is finite, already spoken for by defense programs, and not a flowing supply. The Samarium Magnet Company, a Saudi Arabia-based manufacturer, has positioned itself as a non-Chinese alternative with Gulf-region and African rare earth sourcing — but it is a single facility serving a global demand that Chinese producers had supplied for decades. Energy Fuels in Colorado is exploring rare earth separation using uranium processing infrastructure, but is not producing samarium at commercial scale.

    The NDAA Section 870 deadline compounds the pressure. Effective January 1, 2027, the U.S. Department of Defense will prohibit the acquisition of samarium cobalt and NdFeB magnets that are mined, refined, melted, or produced in China, Russia, Iran, or North Korea. Defense contractors who have been purchasing Chinese-origin SmCo magnets — which, until April 2025, was the only way to purchase SmCo magnets in meaningful volume — have roughly eight months from this writing to secure NDAA-compliant supply chains. Arnold has one. Lynas has started producing samarium oxide. Everyone else is scrambling.

    The April 2025 controls in practice

    The export control process has been worse than the export control announcement. MOFCOM’s April 2025 Announcement No. 18 required export licenses for samarium, SmCo magnets, and SmCo alloys. Provincial commerce bureaus initially communicated 45-60 day review windows. Actual processing times have exceeded those estimates consistently. By mid-2025, Arnold reported that “military-adjacent, aerospace, and sophisticated sensor programs almost never receive approvals.” Commercial applications face intense scrutiny of end-use declarations, and licenses are issued on a per-shipment basis — even identical repeat orders require separate license applications.

    The practical consequence is that Western companies cannot plan production around Chinese SmCo supply. A magnet manufacturer outside China that had legally purchased samarium earlier in 2025 was contractually required to block shipment of finished SmCo ingots after the October controls expanded to cover Chinese-origin minerals used in dual-use applications — even though the alloy was manufactured and processed entirely outside China. The extraterritorial reach is the same mechanism the terbium post documented: China asserts licensing authority over products containing Chinese-origin rare earth inputs at concentrations as low as 0.1%, regardless of where the product is manufactured. The semiconductor supply chain has ASML’s export restrictions limiting Chinese access to EUV lithography. China’s rare earth export controls are the mirror image: limiting Western access to the materials that go inside the machines.

    The cobalt complication adds a second layer of supply risk. Cobalt constitutes roughly 30% of SmCo alloy by mass, and cobalt supply is concentrated in the DRC, where artisanal mining, conflict, and price volatility create their own supply chain constraints. SmCo magnet manufacturers face simultaneous pressure on both inputs: samarium from Chinese export controls and cobalt from DRC supply instability. The intersection of those two constraints — one geopolitical, one geological — is what makes SmCo the most supply-constrained magnet technology in the world.

    The comeback nobody wanted

    The irony of samarium’s 2025-2026 resurgence is that nobody in the magnet industry wanted it. NdFeB was supposed to be the permanent magnet of the future — cheaper, stronger, increasingly available from non-Chinese sources as MP Materials and Lynas expanded light rare earth production. SmCo was the legacy technology, maintained for defense applications where nothing else would do but otherwise declining in commercial relevance. Then China put samarium, terbium, and dysprosium under export controls in the same announcement, and the magnet industry discovered that both its leading-edge technology (high-temperature NdFeB with terbium/dysprosium) and its legacy fallback (SmCo) were simultaneously supply-constrained by the same country’s export licensing regime. The diversification that was supposed to protect the supply chain — “we’ll use NdFeB for commercial and SmCo for defense” — turned out to be diversification within a single point of failure.

    The gallium/germanium controls in 2023 restricted semiconductor feedstock. The antimony controls in 2024 restricted ammunition and flame retardant materials. The graphite controls in 2023 restricted battery anode materials. The April 2025 rare earth controls restricted the magnets that go into everything — EVs, wind turbines, guided missiles, radar, sonar, MRI machines, industrial robots, and the semiconductor lithography equipment that SmCo magnets sit inside. Each escalation in the sequence has targeted a higher-value, harder-to-substitute category of material. Samarium is the escalation that reached the defense industrial base.

    This is the kind of supply chain our Rare Earth Elements course was built to map — where a magnet technology the West invented in the 1970s, let China monopolize in the 2000s, and assumed would always be available as a commodity, became in April 2025 the most restricted defense-critical material on the export control list, with eight months left before U.S. law prohibits the Pentagon from buying it from the only country that produces it at scale.

  • Terbium: The Bottleneck Inside the Bottleneck

    On April 4, 2025, China imposed export controls on seven heavy rare earth elements — samarium, gadolinium, terbium, dysprosium, lutetium, scandium, and yttrium — along with their compounds, metals, alloys, and any magnets containing them. On October 9, 2025, Beijing expanded the controls to include holmium, erbium, thulium, ytterbium, and — critically — “parts, components, and assemblies” containing any of these materials, including products manufactured outside China using Chinese-sourced inputs at concentrations as low as 0.1%. The controls were suspended on November 7, 2025, as part of the Xi-Trump trade agreement, for one year until November 2026. They are, as of this writing, frozen — not withdrawn. Before the suspension, European dysprosium oxide prices reached $900 per kilogram, roughly triple the Chinese domestic price of $255. Terbium oxide was trading at levels that caused suppliers to halt sales to private investors entirely, prioritizing industrial customers. The CEO of Germany’s Vacuumschmelze — one of the few rare earth magnet manufacturers outside China — told Reuters in November 2025: “If you talk about critical resources, it’s really the heavies, the heavies, the heavies — all the rest we will get.” He was talking about terbium and dysprosium. And he was right.

    What terbium does

    Terbium is a heavy rare earth element — atomic number 65 — and its industrial importance is almost entirely about magnets. Neodymium-iron-boron permanent magnets are the most powerful permanent magnets in existence, used in every EV traction motor, every direct-drive wind turbine generator, every hard disk drive, every guided missile, every MRI machine, and most industrial robots. The problem with NdFeB magnets is that they lose their magnetic properties at elevated temperatures — above roughly 80°C, an NdFeB magnet begins to demagnetize. An EV motor operating under sustained load, a wind turbine nacelle in summer heat, a fighter jet engine bay — all exceed that threshold. Adding small quantities of terbium or dysprosium to the alloy extends the operating temperature range to 200°C or higher. The addition is small — a few percent by weight — but the effect is the difference between a magnet that works in a laboratory and a magnet that works in a car.

    Terbium is the more effective of the two heavy rare earth additives — it provides stronger coercivity enhancement per unit of concentration than dysprosium — but it’s also rarer and more expensive. In practice, magnet manufacturers use both, often in combination, depending on the application’s thermal requirements and the relative cost and availability of each. For the highest-performance applications — military systems, aerospace actuators, precision guidance systems — terbium is preferred. For lower-temperature applications, dysprosium suffices.

    Beyond magnets, terbium has a secondary role in phosphors — it emits a vivid green light when excited, which made it essential for color television, fluorescent lighting, and trichromatic display systems. LED technology has largely displaced fluorescent phosphors, but terbium-based phosphors remain relevant in medical imaging, scientific instruments, and specialized displays. Terbium is also the primary component of Terfenol-D — an alloy of terbium, dysprosium, and iron that exhibits the strongest magnetostriction of any known material, meaning it physically expands and contracts in response to magnetic fields. Terfenol-D is used in naval sonar transducers, precision actuators, and vibration sensors. A submarine’s ability to detect other vessels depends, in part, on terbium.

    Where 98% comes from

    China controls over 90% of refined terbium supply. The highest-grade commercial deposits are ion-adsorption clays in southern China — Jiangxi, Guangdong, Fujian — where heavy rare earths are adsorbed onto clay particles and extracted by leaching with ammonium sulfate. A ton of clay yields a few hundred grams of mixed rare earth oxides, of which terbium might constitute a few grams. The extraction is low-tech, environmentally destructive (the leaching process contaminates groundwater and strips hillsides), and labor-intensive — but the deposits are uniquely rich in the heavy rare earths the magnet industry needs.

    Myanmar has become the second most important source of heavy rare earth ore — mined primarily in the Kachin and Wa states by ethnic militias operating in a civil war zone, shipped across the Chinese border, and processed in Chinese separation facilities. The ore flows through a corridor that China effectively controls on both ends: the armed groups who mine it depend on Chinese buyers, and the separation capacity that converts raw ore into usable oxide is 98-99% concentrated in China. Conflict minerals is a term usually applied to the DRC’s cobalt and coltan supply chains. The Myanmar heavy rare earth trade has the same structural characteristics — extraction in a conflict zone, processing controlled by an external power, and end-use in consumer products whose buyers rarely ask where the material came from.

    The West has deposits but not capacity. MP Materials’ Mountain Pass mine in California produces light rare earths — neodymium and praseodymium — but contains only traces of terbium and dysprosium. Lynas Rare Earths in Australia began heavy rare earth separation in Malaysia in 2025, becoming the first non-Chinese heavy rare earth separator on Earth — but at initial volumes of roughly 250 tonnes of dysprosium and 50 tonnes of terbium per year, it’s a fraction of global demand. Energy Fuels, a Denver-based uranium miner, is pivoting to rare earth separation using similar process chemistry — but is not yet producing at scale. Brazil is emerging as an ore exporter, but as Benchmark Mineral Intelligence noted, “the technology for HREE refining is expected to be available globally by 2029” and “costs outside of China remain 5-7 times higher.” The problem is not that heavy rare earth deposits don’t exist outside China. The problem is that the separation and refining capacity to convert those deposits into usable materials is, as of 2026, a Chinese monopoly with a few early-stage Western competitors years away from meaningful scale.

    The April 2025 export controls

    The April 2025 controls followed the same escalation pattern the Rare Earth Elements course has documented across gallium/germanium (July 2023), graphite (October 2023), antimony (August 2024), and tungsten (early 2025) — but with a crucial escalation. The earlier controls restricted raw materials and processed forms. The April 2025 controls restricted magnets containing terbium and dysprosium — finished products, not just feedstock. The October 2025 expansion went further: it applied extraterritorial jurisdiction to “parts, components, and assemblies” containing Chinese-sourced rare earth materials, even if manufactured outside China, even if traded domestically in a third country. A European carmaker using a motor containing a magnet with 0.1% Chinese-origin terbium would, under the October rules, need a Chinese export license for the motor — not for the terbium, for the motor.

    The IEA reported that after the April controls took effect, “many carmakers in the United States, Europe, and elsewhere struggled to obtain permanent magnets, with some forced to cut utilisation rates or even temporarily shut down factories.” European rare earth prices reached up to six times Chinese domestic prices. The November 2025 suspension froze the escalation but did not reverse it. The controls remain on the books. The licenses remain at Beijing’s discretion. The semiconductor supply chain has TSMC in Taiwan. The lithium supply chain has Chinese refining. The magnet rare earth supply chain has something worse: Chinese separation capacity so dominant that the export controls don’t just restrict supply — they assert jurisdiction over finished products manufactured anywhere in the world using Chinese-origin inputs. That’s not a trade restriction. That’s extraterritorial industrial policy.

    Why terbium is the real bottleneck

    McKinsey projects global demand for magnet rare earths will triple from 59,000 tonnes in 2022 to roughly 176,000 tonnes by 2035. Under rapid clean-energy adoption scenarios, terbium requirements could reach 134-256% of available supply — meaning the energy transition needs one-and-a-half to two-and-a-half times more terbium than the planet currently produces. The EU projects that demand for rare earth magnets could increase tenfold by 2050. The projected 60,000-tonne shortfall by 2035 — approximately 30% of total requirements — is concentrated in the heavy rare earths, not the lights. Neodymium and praseodymium can be sourced from Mountain Pass, from Lynas, from emerging projects in Brazil and Africa. Terbium and dysprosium cannot — not at the volumes the market needs, not at processing costs the market can absorb, and not from facilities that currently exist outside Chinese control.

    Every EV motor, every wind turbine, every humanoid robot actuator, every military guidance system that requires a high-temperature permanent magnet runs into the same constraint: the heavy rare earths that make the magnet work at temperature come from one country, are separated in one country, and are now subject to export controls that assert jurisdiction over products made in every other country. The nickel supply chain was restructured by Indonesian resource nationalism in five years. The terbium supply chain was never diversified enough to restructure — it started concentrated and stayed concentrated, and the concentration is now being weaponized.

    This is the kind of supply chain our Rare Earth Elements course was built to map — where the element that allows an EV motor magnet to survive operating temperature is separated from clay in southern China and a civil war zone in Myanmar, refined in facilities that are 98% Chinese-controlled, subject to export controls with extraterritorial reach, and projected to be in deficit by 2035 under every growth scenario the energy transition requires.