Key takeaways
- NdFeB delivers 30–50% higher energy density than SmCo at equivalent temperature ratings up to ~180°C.
- SmCo 2:17 operates to 300–350°C continuous, well beyond any commercial NdFeB grade.
- SmCo has ~4x lower temperature coefficient of Br (~-0.03%/°C vs NdFeB's -0.12%/°C), so SmCo is more thermally stable even where NdFeB technically works.
- NdFeB requires coating to prevent corrosion; SmCo is essentially immune to atmospheric corrosion and used uncoated in most environments.
- NdFeB is 30–60% cheaper per MGOe at 2026 pricing. SmCo cost pressure comes from cobalt (strategic material), not rare earths.
- Both are subject to China MOFCOM export licensing, switching materials does not avoid licensing requirements.
Overview
Overview
NdFeB (neodymium-iron-boron) and SmCo (samarium-cobalt) are the two commercial rare earth magnet materials. NdFeB dominates by volume (roughly 90:1 ratio in global production) because of its higher energy density and lower cost. SmCo retains a niche where its temperature stability and corrosion resistance are decisive design factors.
Both materials require thoughtful grade selection, and for designs in the 150–230°C envelope, both should be evaluated in parallel.
Side-by-side
Side-by-Side Comparison
Wins by criterion
NdFeB (Neodymium) leads on more criteria
4
NdFeB (Neodymium)
3
SmCo (Samarium-Cobalt)
1
Even
| Criterion | NdFeB (Neodymium) | SmCo (Samarium-Cobalt) |
|---|---|---|
| Max BHmax (premium grades) | ✓Up to 58 MGOe (N52–N58) | Up to 32 MGOe (SmCo 2:17) |
| Max Operating Temperature | 230°C (AH grades) | ✓300–350°C (SmCo 2:17) |
| Temperature Coefficient Br | -0.12%/°C | ✓-0.03%/°C |
| Corrosion Resistance (uncoated) | Poor | ✓Excellent |
| Cost per MGOe | ✓Lower (baseline) | 2–4x NdFeB |
| Mechanical Strength (flexural) | ✓~250 MPa | ~120 MPa |
| Heavy Rare Earth Dependence | Dy/Tb for high temp | Samarium (controlled) |
| Global Production Volume | ✓~220,000 t/yr | ~2,500 t/yr |
✓ indicates the better option for the criterion. Winner assignment reflects typical engineering practice; your application may weight criteria differently.
Use cases
When Each Is the Right Choice
When NdFeB (Neodymium) wins
- Operating temperature at or below 230°C continuously
- Cost-sensitive production applications
- Designs requiring maximum flux density in minimum volume
- Applications where mechanical robustness matters (NdFeB is less brittle)
When SmCo (Samarium-Cobalt) wins
- Operating temperature continuously above 230°C (downhole, extreme-temperature industrial)
- Applications with wide temperature swings where thermal stability of flux is critical
- High-vacuum applications requiring zero outgassing
- Designs where coating pinhole integrity is a reliability concern
How to choose
Decision Framework
Decision framework
Start with operating temperature. Above 230°C continuous, SmCo 2:17 wins by default, NdFeB simply does not operate there. Between 150–230°C, evaluate both: NdFeB UH and EH grades offer competitive total-cost positions with the GBD processing premium, while SmCo offers inherent thermal stability without compensation design. Below 150°C, NdFeB is almost always the correct material, cheaper, higher BHmax, easier to procure at volume.
Specs
Related NdFeB Grades
N42UH
180°CHigh-performance UH-grade NdFeB for the most demanding traction and high-temperature industrial motor applications.
N45UH
180°CTop-tier UH-grade NdFeB, rare production, reserved for the highest-performance traction and extreme-temperature motors.
N42EH
200°CHighest EH grade in this reference set, at the 200°C rating that defines the EH class.
N38EH
200°CHigher-flux EH-grade NdFeB for the most demanding 200°C applications in energy and extreme-temperature industry.
Industries
Related Applications
EV Motors
High-performance NdFeB magnets for electric vehicle traction motors, auxiliary drives, and e-axle systems, with the temperature stability and flux density required for continuous high-torque service.
Medical Devices
Precision NdFeB magnets for MRI equipment, surgical robotics, implantable devices, dental applications, and medical sensors, with the biocompatibility and traceability medical programs require.
Questions
Frequently Asked Questions
Which is stronger, NdFeB or SmCo?
+
NdFeB is stronger in terms of energy density, the most powerful commercial NdFeB grades (up to N58) deliver as much as 58 MGOe, versus up to 32 MGOe for the strongest SmCo (SmCo 2:17). In practical motor design, NdFeB allows smaller, lighter motors at the same torque output. However, SmCo wins at elevated temperatures where NdFeB flux would demagnetize.
Why is SmCo used instead of NdFeB?
+
SmCo is chosen when its specific advantages outweigh NdFeB's higher energy density. These scenarios include: continuous operation above 230°C, applications with wide temperature swings where thermal stability of flux matters, high-vacuum use (SmCo has near-zero outgassing), and environments where coating pinhole reliability is a concern (SmCo is essentially immune to atmospheric corrosion uncoated).
Is SmCo cheaper than NdFeB?
+
No, SmCo is typically 2–4x more expensive than NdFeB per MGOe of energy product at 2026 pricing. The cost pressure on SmCo comes primarily from cobalt content, cobalt is a strategic material with volatile pricing tied to battery supply chains. NdFeB cost pressure tracks rare earth markets (NdPr, Dy, Tb) and is usually lower per unit of magnetic work delivered.
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