Development of a rapid cooling atomizing method and production of high-Bs nanocrystalline powders containing large-sized particles

We attempted to produce nanocrystalline soft magnetic powders with a high saturation magnetic flux density (Bs) and containing large-sized particles using a modified water atomization system named “HPWA/YK.” Almost fully amorphous powders containing particles with median diameters of 15 μm and composed of Fe83.3Si4B8P4Cu0.7 were obtained. These results indicate that HPWA/YK reached a higher quenching rate than conventional water atomization systems. The powder circularity reached a value of 0.78 by changing the ratio of the gas to water pressure; moreover, after annealing at 713 K, the powders presented good magnetic properties (Bs = 1.66 T; Hc = 155 A/m).