Preparation and properties of hot-deformed magnets processed from nanocrystalline/amorphous Nd-Fe-B powders

The hot-deformed magnets processed from nanocrystalline/amorphous Nd-Fe-B powders were prepared under different hot-pressing temperatures (600-750 degrees C, at intervals of 25 degrees C) by the self-made hot-pressing equipment. The microstructure and magnetic properties of hot-deformed magnets prepared at different temperatures were also investigated. When the temperature is above 650 degrees C, the density of magnet reaches 7.5 g center dot cm(-3). The optimum magnetic properties of magnetic induction intensity ofB(r) = 1.3 T, optimum energy product of (BH)(max) = 282.5 kJ center dot m(-3), intrinsic coercivity ofH(cj) = 1130.0 kA center dot m(-1)of hot-deformed magnets are obtained at hot-pressing temperature of 650 degrees C. X-ray diffractometer pattern shows that the (00L) texture has been obtained. For the microstructural characteristic, on the one hand, the good magnetic performance is attributed to the fine platelet-like grains with an average length of 410-440 nm at the hot-pressing temperature range from 625 to 675 degrees C. On the other hand, the unaligned coarse grains are observed in all the samples. And the areal fraction of those is gradually increasing with the rise of the hot-pressing temperature, which tends to deteriorate the magnetic properties. The composition map shows the accumulation of Nd/Pr-rich phase in the coarse grains' region.

Automated summary

Hot-deformed magnets processed from nanocrystalline/amorphous Nd-Fe-B powders were prepared at different hot-pressing temperatures. The optimal magnetic properties were achieved at a hot-pressing temperature of 650 degrees C, with the presence of fine platelet-like grains contributing to superior magnetic performance. The accumulation of Nd/Pr-rich phase in the coarse grains' region tends to deteriorate the magnetic properties as the hot-pressing temperature increases.