6 - Hot-deformed NdFeB permanent magnets

Abstract

This chapter covers the preparation and properties of hot-pressed and hot-deformed NdFeB magnets prepared from melt-spun NdFeB magnetic powders. In contrast to bonded Nd magnets, which consolidates the melt-spun ribbon fragments together by compaction with a resin, hot-pressed magnets are consolidated into nearly 100% dense anisotropic intermetallic bodies by the application of heat and pressure. No alignment field is used during the processing as is the case for sintered Nd magnets and alignment occurs entirely by thermomechanical means. This alignment process is reviewed, as is the current view on the magnetization process and coercivity mechanism that is applicable to these hot-deformed magnets. Currently the major product produced by the hot deformation of rapidly solidified magnetic powder is radially aligned ring magnets that are produced by a back extrusion process and this process is also discussed. Anisotropic-bonded magnets can also be prepared from powder produced by crushing the hot-deformed magnet and the preparation and properties of these magnets are also discussed.