As this study is a preliminary study to improve a soft magnetic property of Fe based nanocrystalline alloy powder cores, by analyzing the soft magnetic properties (permeability, core loss and DC bias) according to the composition change of alloying element (Si,Nb), powder size and amount of insulator when making powdered core, the result could be concluded like below.

First, by making a ribbon from FINEMET (Fe73.5Si13.5B9Nb3Cu1) alloy composition using the PFC, heat treatment and micro grinding were used. Then, according to the change of using amount of insulator from 0.5 to 2.5wt%, the permeability was decreased. However, it was confirmed that the core loss and the DC bias property were increased. 1wt% is the most proper for the amount of insulator.

Second, as a result of analyzing a soft magnetic property of the powdered core in accordance with the size after fixing the insulator as 1wt% and sieving the amorphous alloy power that is pulverized by ball mail as 100 to 500 mesh, the property of the core that is produced by the alloy powder in 74 to 125㎛ range was the most outstanding. The reason is because of the insolation effect and the density difference of core molding according to the thickness of a coating layer.

Third, we studied the property of the powdered core by changing the amount of Si and Nb to improve the soft magnetic property of FINEMET (Fe73.5Si13.5B9Nb3Cu1) and the results are like below.

① In case of Fe73.5-X-ySixB9NbyCu1(X=7, 9, 11, 12. 5 and13 Y=3) nanocrystalline alloy, the permeability is the most outstanding when the amount of Si is 12.5at%. In 13at%, the core loss is the lowest as 467mW/cc (50 kHz). In this result, through 42% of the permeability is increased compared to FINEMET, the core loss and the DC bias decrease to 92% and 22.5%.
② In case of Fe73.5-X-ySixB9NbyCu1(X=13.5, Y=0.5,1,2,3) nanocrystalline alloy, in 2at% of amount of Nb, the permeability is the highest as 161 and the core loss is the lowest as 418mW/cc (50 kHz). Also, the DC bias shows the outstanding value (about 32%). Compare to FINEMET, in this result, 61% of the permeability is improved, 72% of the core loss is increased and about 34% of DC bias is decreased.

Like the results, in this study, by changing the amount of Si and Nb in FINEMET, the properties of the powdered cores are compared. As a result, in case of two alloy compositions of aforementioned ① and ②, while the permeability is highly increased, the core loss and the DC bias are highly decreased.