MAGNETIC AND MICROSTRUCTURAL PROPERTIES OF SINTERED FENDB-BASED MAGNETS WITH GA AND NB ADDITIONS

Sintered magnets based on the Fe14Nd2B phase were prepared by alloying the additive elements Ga and Nb, which mainly influence the microstru cture and not the intrinsic magnetic properties. The room-temperature permanent magnetic properties are the intrinsic coercivity, mu(0)H(c) = 1.70 T and the remanent polarization, J(r) = 1.20 T. From the temper ature dependence of the coercive field the microstructural parameters alpha(K) and N-eff were determined. Furthermore, the Kerr microscopy w as used to investigate the domain patterns and the microstructure. Pha se analyses showed that the low-melting element Ga forms new intergran ular phases and the refractory metal Nb forms high-melting borides in the intergranular phases and small precipitates in the hard magnetic g rains.