Bulk anisotropy Nd‐Fe‐B/α‐Fe nanocomposite permanent magnets prepared by sonochemistry and spark plasma sintering

Abstract

Abstract NdFeB/α‐Fe nanocomposite magnetic powders were prepared by sonochemical process. The powders were then submitted to a hot press and subsequent hot deformation process by spark plasma sintering (SPS) technique. Effect of α‐Fe content on structure and magnetic properties of both isotropic and anisotropic magnets was investigated. For hot pressed magnets, the remanence increases with the content of α‐Fe, while the coercive force drops simultaneously. After hot deformation, the magnets with no more than 2 vol% α‐Fe exhibit obvious anisotropic characteristic. For the magnets with more α‐Fe, however, the magnetic anisotropy disappears due to the absence of (00 l ) crystal texture after deformation. It is, therefore, expected that α‐Fe content plays an important role in the formation of C‐axis crystal texture during hot deformation process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)