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

Abstract

Amorphous Fe 78Si 9B 13 and (Fe 0.78Si 0.09B 0.13) 97 Cr 3 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 B 8 k = 0.54 T, maximum permeability μ max = 220 and coercive force H c = 264 A m −1 for an Fe 78Si 9B 13 composite core. It should be noted that the B 8 k 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.