Uniformly high-performance Nd-Fe-B magnet powder (abstract)

Isotropic Nd‐Fe‐B bonded magnet powder is currently produced by the rapid quenching of the molten alloy by the melt spinning. An alternate route was investigated to produce spherical particles of Nd‐Fe‐B alloy having high magnetic properties, particularly coercivity, because spherical powders have excellent flowability. It was found that the magnetic properties of gas atomized spherical Nd‐Fe‐B powders were substantially improved by hydrogen absorption‐desorption (HAD) treatment at 700–800 °C. However, the previous HAD treatment1 causes nonuniform magnetic properties as well as nonuniform microstructure across the sample location of the load in the furnace. Change in process variables does not substantially improve the uniformity in magnetic properties across the sample load. A unique HAD treatment resolves the nonuniformity in microstructure and magnetic properties, and further uniformly improves the magnetic properties. The uniform and high magnetic properties may be due to uniformly fine grain size pro...