On the Squareness Factor Behavior of RE-FeB (RE $=$ Nd or Pr) Magnets Above Room Temperature

The magnetic stability of RE-FeB (RE = Nd or Pr) sintered magnets above room temperature was investigated by monitoring the squareness factor (SF). At 293 les T les 423 K, commercial anisotropic NdFeB-based sintered magnets with a Curie temperature (T _c) of around 585 K showed no appreciable change in their squareness factors. This indicates that the SF is controlled mainly by the samples´ microstructural features. Magnets with T _c > 593 K showed a tendency for improved squareness factor at higher temperatures due to the methodology employed to characterize the SF. On the other hand, PrFeCoBCuNb sintered magnets with T _c > 593 K presented a reduction in the SF with temperature rising from 298 to 373 K.