Yoshio Harakawa

Production of flaky Fe-based amorphous powders by a two-stage quenching technique and their magnetic properties

Abstract Amorphous Fe78Si9B13 and (Fe0.78Si0.09B0.13)97 Cr3 powders were produced by the two-stabe quenching technique. These amorphous powders have a flaky morphology, with a disk or an ellipsoidal shape. The thickness is as small as 1–3 μm and the aspect ratio is as large as 20–300. The composite consisting of the flaky amorphous powders embedded in phenol resin exhibits soft magnetic properties of a magnetic induction of B8k = 0.54 T, maximum permeability μmax = 220 and coercive force Hc = 264 A m−1 for an Fe78Si9B13 composite core. It should be noted that the B8k value is 2.1 times as high as that for the composite of amorphous CoFeSiB flaky powders and resin. The μ′ value of the composite core made from insulated flaky powder and phenol resin remains almost unchanged in the high frequency range up to 10 000 kHz. Judging from the combined characteristics of the unique powder morphology and the magnetic properties inherent to the Fe-based amorphous phase, the flaky amorphous powders are concluded to have an enhanced engineering potential.