Bulk α-Fe/Nd2Fe14B nanocomposite magnets produced by severe plastic deformation combined with thermal annealing

Bulk alpha-Fe/Nd2Fe14B nanocomposite magnets with a maximum energy product up to 17.5 MG Oe have been successfully produced, using Nd9Fe85B6 with a few alpha-Fe crystallites in an amorphous matrix as precursors, by a combination of severe plastic deformation at room temperature and thermal annealing. The alpha-Fe and Nd2Fe14B composite nanocrystals are induced in the amorphous matrix during the room-temperature deformation, which have a significant effect on the microstructure development of a small and uniform grain size in the bulk alpha-Fe/Nd2Fe14B nanocomposite magnets produced from the deformed alloy by thermal annealing. Moreover, a high volume faction up to 36% for soft-magnetic phase is achieved in the deformation-processed bulk magnets. These lead to enhanced magnetic properties in the magnets as compared with those fabricated from nondeformed ribbons. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3480789]