Bonded anisotropic Nd-Fe-B magnets from rapidly solidified powders

There has been great interest in using Nd-Fe-B material for bonded magnets. Bonded magnets made using rapidly solidified powders are limited to maximum energy products of ∼10 MGOe. Anisotropic Nd-Fe-B magnets having high-energy products can be prepared by hot deformation of rapidly solidified material. They can be converted into stable powders for processing into bonded anisotropic magnets. The stability of this powder is better than that prepared by grinding sintered magnets. The stability data at 80, 100, and 125 °C for coated and uncoated anisotropic powders prepared by converting hot deformed anisotropic magnets into powder are given. The data indicate the need for additional protection for higher operating temperatures. Bonded magnets having maximum energy product of 15.8 MGOe with intrinsic coercivity of 14.5 kOe have been made. Data will be given showing the effect of particle size on the magnetic characteristics. Long-term thermal stability data for bonded magnets are given. Coating of particles reduces the structural losses during long-term thermal aging.