Rare Earth Magnets Are Mechanically Fragile, Not Just Strong
NdFeB magnets are hard but brittle, a real mechanical trade-off engineers manage with coatings and containment, not a flaw that gets designed away.
The same intermetallic structure that gives NdFeB magnets their exceptional magnetic energy product, covered on this material’s materials science page, also makes them mechanically brittle, a real trade-off, not a missed opportunity for improvement.
Hard but brittle, a genuine materials pairing
NdFeB magnets are hard enough to resist scratching and wear in normal handling, but they fracture rather than deform under impact or bending stress, the same general hard-versus-tough trade-off covered on cobalt’s mechanics page for WC-Co cemented carbide, just pushed further toward hardness and away from toughness.
Why every NdFeB magnet is coated
Beyond brittleness, the iron content that makes NdFeB’s magnetism possible also makes it corrode readily if left bare, so commercial magnets are routinely coated (nickel, zinc, or epoxy are common choices) specifically to manage this, a real, necessary manufacturing step rather than a cosmetic finish.
Why this shapes how motors are actually built
Because of this brittleness, NdFeB magnets in an EV motor or wind turbine generator, covered on this material’s application-wise page, are mounted and contained to avoid tensile and impact loading directly on the magnet itself, the rotor structure is engineered around the magnet’s mechanical limitation, not despite it.
Sources: NdFeB mechanical properties and coating practices draw on standard permanent magnet engineering references.