Grain growth and alignment in hot deformed Nd-Fe-B magnets

Formation of grain oriented Nd-Fe-B magnets from melt-spun ribbons by hot deformation has been studied using electron microscopy. It is shown that deformation and alignment of Nd2Fe14B magnets result from a combination of plastic deformation, grain boundary migration, and grain boundary sliding. Due to a limited number of available slip systems in this material, samples with large grains deform less easily. Small grain size materials, as encountered in the melt-spun ribbons, are well suited for die-upsetting to produce oriented magnets.