Comparison of Mixed Rare Earth Iron Boride Gas Atomized Powders to Melt Spun Ribbon for Bonded Isotropic Permanent Magnets

摘要

Bonded isotropic permanent magnets (BPMs) formed by injection or compression molding offer good corrosion resistance and the capability for net shape manufacturing. Substituting Y and Dy for Nd in Nd_2Fe_(14)B results in a mixed rare earth iron boride (MRE-Fe-B) for use in BPMs. Microstructures of MRE-Fe-B powders directly affect the magnetic properties of the BPMs. Melt spinning has been used to process Nd-Fe-B alloys to achieve the necessary grain structure to maximize the magnetic properties. Due to the plate-like particulate that results from melt spinning the maximum energy product may not exceed that achieved by spherical powders in an injection molded bonded magnet due to polymer compound viscosity and fill factor considerations. Producing spherical powders allows for a higher fill factor, increasing the maximum energy product. Gas atomization offers rapid solidification effects that promote glass formation or uniform fine microsegregation to the particulate and produces spherical particles. Comparisons of melt spun and gas atomized MRE-Fe-B powder will be reviewed.