PREPARATION AND TEM-STUDY OF SINTERED ND18FE74B6GA1NB1 MAGNETS

Ga-doped Nd-Fe-B sintered magnets show an improved wetting behaviour o f the liquid phase during sintering and the formation of additional Ga -containing intergranular phases. Nb forms precipitates within the ha rd magnetic phase and an intergranular boride-phase. This improves the separation and decoupling of the hard magnetic grains and enhances th e coercivity. In the as-sintered magnets we find a new Nd-rich Ga-cont aining region which contains Nd3Ga and NdsGa3. This region is formed f rom the liquid phase during cooling. In addition the delta-phase occur s in the annealed magnets. Nb is found in the hexagonal NbFeB intergra nular boride and in small Nb-containing precipitates within the hard m agnetic phase. There is no Nb detected in the Nd-rich phases.