Developments in Melt Spun Powders for Permanent Magnets

Bonded and fully-dense magnets prepared from melt-spun RE2Fe14B-type powders continue to find new applications in consumer electronics, automotive and industrial motors. The unique nanostructure of these materials promotes high magnetic performance, environmental stability and near-net shape formability. This article reviews the various types of melt spun powder from a compositional and microstructural standpoint. The powder with best overall performance and stability for bonded magnets appears to be the RE2Fe14B single phase type. Additional corrosion resistance can be achieved by coating the powder with an organic micro-dispersion prior to molding. Regarding higher performance fully dense magnets, multi-phase RE2Fe14B/RE melt spun powder offers a highly flexible precursor for hot forming near-net shape isotropic and anisotropic magnets. The composition of the melt spun powder along with the degree of hot deformation can be tailored to provide a range of magnetic properties from these types of magnet.