Magnetic properties of B-rich (Fe, Co)–Nb–B amorphous alloys

The magnetic properties of melt spun Fe52−xCo10+xNb8B30 (x = 0, 12, 24, 36) amorphous ribbons are presented and discussed. The Curie temperature together with the saturation magnetization exhibited a progressive decrease with increasing Co addition (from 631 to 512 K and from 1.24 to 0.53 T, respectively). On the other hand, the ac initial magnetic permeability displayed a diminishing trend with increasing Co content, from 7500 to 1500 at f = 0.5 kHz together with a relaxation frequency variation between 2 and 7 kHz. In addition, the alloys magnetostriction showed a decreasing tendency with increasing cobalt concentration. Results are interpreted on the basis of the detrimental effect of Co on the intrinsic magnetic properties of the alloy series.