Highly heat-resistant Nd-Fe-Co-B system permanent magnets

The magnetic properties and crystal structures of sintered Nd-Fe-Co-B magnets have been investigated over a wide range of chemical composition. Magnetic hardening is performed for samples by a post sintering heat treatment at
500\sim1000\deg
C. The curie temperature of these samples are significantly improved with the increase of cobalt content. The sample with the composition of Nd
16
Fe
66
Co
11
B
7
shows remarkable magnetic properties, such as the maximum energy product of 42 MGOe and the reversible temperature coefficient of residual magnetization of 0.02 %/°C, Electron probe microanalysis and x-ray data suggests that the highly heat resistant magnet is produced when cobalt distributes only in the tetragonal matrix phase.