Abstract
Partial crystallization is an effective technique to reduce high frequency core loss in iron-based amorphous ribbons. In this paper, we report a new method to control the number of crystalline particles in amorphous matrix and to reduce high frequency core loss.
Fe80B20-xZrx ribbons (x=0, 0.2, 0.5, 0.7, 1.0) were prepared by a rapid quenching technique. Although as-prepared Fe80B20 ribbons are completely amorphous, ribbons containing zirconium are locally crystallized during rapid quenching. The micro-crystal precipitates (Fe3B+Fe23B6) are dispersed in the thin free surface layer and their number can be controlled by varying zirconium content. The controlled precipitates suppress the eddy current loss and reduces the high frequency core loss. The core loss (Bm=0.3 T, f=60 kHz) in Fe80B20-xZrx ribbons shows a minimum at x=0.7 and the minimum value of core loss is about 80% of that in the completely amorphous Fe80B20 ribbons. Stability of magnetic properties in Fe80B19.3Zr0.7 ribbon was checked and it was confirmed that the core loss is kept constant up to 600 minutes for 350°C annealing.
