Local texture in Nd–Fe–B sintered magnets with maximised energy density

Sintered Nd–Fe–B magnets, one of which showed a maximised energy density as high as (BH)max=451 kJ/m3 (56.7 MGOe) at room temperature, have been produced by optimisation of alloy composition, minimisation of impurities, improved alignment of the powder particles and a controlled sintering process. For the first time, large scale microtexture analysis using electron backscatter diffraction (EBSD) has been carried out on sintered Nd–Fe–B magnets. Large orientation maps in both directions, parallel and perpendicular to the texture axis, were acquired in a thermal field emission gun scanning electron microscope (FEGSEM). Domain patterns of the same areas have been obtained using magneto-optical Kerr-microscopy. Thereby, a quantitative description of local texture could be correlated effectively with domain patterns of individual grains and with backscattered electron images. Distinction between individual grains in the Kerr-images was more difficult due to the excellent alignment of the grains in the magnet with the maximised energy density. Pole figures were used to evaluate EBSD patterns.