Fe_70-xNd₇B₂₁Zr₂Nb< sub>x (x=0-3.0) Permanent Magnets Produced by Crystallizing Amorphous Precursors

The phase evolution, magnetic properties and microstructure of rod-shaped permanent magnets prepared by annealing the amorphous precursor Fe70-xNd7B21Zr2Nbx (x = 0-3.0) were systematically studied. X-ray diffraction analysis, magnetometer, microstructure and delta M-plots studies show that the good magnetic properties of the magnet are attributed to the uniform microstructure composed of exchange-coupled alpha-Fe and Nd2Fe14B phases. Nb addition to Fe67.5Nd7B21Zr2Nb2.5 alloy led to an increase in the volume fraction of the soft magnetic phase, reinforced exchange coupling and improved magnetic properties. The magnetic properties of the optimized annealed Fe67.5Nd7B21Zr2Nb2.5 rod are: coercivity (H-ci) = 513.92 kA/m, remanence (B-r) = 0.58 T, squareness (H-k/H-ci) = 0.24 and magnetic energy product ((BH)(max)) = 37.59 kJ/m(3).