抄録
Fully dense magnets were prepared by hot pressing of the hydrogenation-decomposition-desorption-recombination (HDDR)-processed powders, and they had very fine microstructures. The typical magnetic properties of the HDDR hot pressed magnet with the composition of Nd13.0Fe62.9Co17.4B6.2Zr0.1Ga0.4 were Br=1.26 T, HcJ=969 kA/m and (BH)max=279 kJ/m3. The magnetic properties and the surface morphology of the machined HDDR thin hot pressed magnets were investigated. The performance of the machined thin hot pressed magnets hardly depended on their thickness, and that of high coercivity magnets with the composition of Nd12.4Dy0.6Fe74.5Co5.8B6.2Zr0.1Ga0.4 is the same because of their fine microstructures. Furthermore, the thin hot pressed magnets hardly depended on damage by surface roughness. We investigated the long-term stabilities. As a result, the total irreversible flux loss of high coercivity hot pressed magnet with the composition of Nd12.6Dy0.6Fe58.8Co20B6.2Zr0.1Ga0.4Al1.5 at 423 K was -1.3% after 1000 hours. The HDDR hot pressed magnets make it possible to stabilize the magnetic properties of thin Nd-Fe-B magnets because of their very fine microstructure.
