Technology · Established
A strong magnetic field in a compact material
Neodymium–iron–boron magnets connect alloy chemistry, grain structure and thermal limits to motors and generators.
THE MATERIAL THAT DOES THE WORK
Chemical form
NdFeB magnets are engineered of neodymium, iron and boron, often including praseodymium and other additions. Some grades use dysprosium or terbium. The name describes a material family whose members have different magnetic and temperature characteristics.
Rare Earth Permanent Magnets: Supply Chain Deep Dive Assessment
- 01
Separate and alloy
Rare-earth feedstocks are separated and , then combined with iron, boron and selected additions for magnet manufacture.
- 02
Orient the microstructure
Powder alignment, pressing and sintering establish the material; finishing and protective coatings prepare it for magnetization.
- 03
Integrate into a machine
The chosen grade operates within a motor or generator whose temperature, field conditions and environment constrain its performance.
Rare Earth Permanent Magnets: Supply Chain Deep Dive AssessmentNeodymium Magnets (NdFeB)
How the application developed
The Japan Prize Foundation dates Masato Sagawa’s Nd–Fe–B magnet breakthrough to 1982; his work with the Sumitomo Special Metals team developed a sintered magnet. In 1984, J. F. Herbst, J. J. Croat, F. E. Pinkerton and W. B. Yelon reported the structure of Nd₂Fe₁₄B using . Their paper discussed strong magnets made from melt-spun alloys, a different processing route. Development through the 1980s and 1990s also addressed heat and performance through alloy changes and coatings.
Masato Sagawa: development of Nd–Fe–B permanent magnets (2012 award account)Relationships between crystal structure and magnetic properties in Nd₂Fe₁₄B (1984)
Why it works
These magnets provide strong magnetic performance in a compact volume. Their usefulness depends on maintaining magnetization under the application’s temperature and opposing fields. A grade optimized for one operating condition may be unsuitable for another.
How it is made & used
A common route converts a cast alloy into fine powder. Particles are aligned in a magnetic field, pressed and sintered. The resulting pieces are shaped, protected against corrosion and magnetized; structure and orientation are central manufacturing outcomes.
Rare Earth Permanent Magnets: Supply Chain Deep Dive Assessment
Inside the application
Permanent magnets are intermediate components in larger products, including some electric motors and wind-turbine generators. Their compactness can help a machine design, but its operating temperature and magnetic circuit help determine which magnet grade can actually be used.
Rare Earth Permanent Magnets: Supply Chain Deep Dive Assessment
Limits & alternatives
Heat and corrosion are important limits. Protective coatings are commonly needed in humid environments. Comparing grades requires magnetic output at the intended temperature, not just a room-temperature label; samarium–cobalt is another rare-earth magnet family used in different conditions.
Part of a larger system
Grain-boundary diffusion can improve resistance to demagnetization while heavy-rare-earth requirements relative to conventional production routes. This illustrates how changing the distribution of an element can matter as much as changing its total amount.
Sources & further reading
- Rare Earth Permanent Magnets: Supply Chain Deep Dive Assessment ↗U.S. Department of EnergyTechnical documentation · Source checked Where to look: Section 2.2.3, printed pp. 13–15 / PDF viewer pp. 27–29; Figures 7–8 cover alloy and sintered-magnet manufacturing.These passages distinguish bonded and sintered magnets and describe the process used in the article; they do not make it universal.
- Neodymium Magnets (NdFeB) ↗Arnold Magnetic TechnologiesTechnical documentation · Source checked
- Masato Sagawa: development of Nd–Fe–B permanent magnets (2012 award account) ↗Japan Prize FoundationHistorical account · Source checked
- Relationships between crystal structure and magnetic properties in Nd₂Fe₁₄B (1984) ↗American Physical Society; J. F. Herbst, J. J. Croat, F. E. Pinkerton and W. B. YelonOriginal research · Source checked Where to look: PDF viewer p. 1: abstract, introductory melt-spun-alloy discussion, neutron-diffraction method and Table I.The paper reports a crystal-structure determination; this should not be confused with the sintered-magnet development account.
Sources and further reading. What the review labels mean