MAGNETIC-PROPERTIES OF VERY HIGH PERMEABILITY, LOW COERCIVITY, AND HIGH ELECTRICAL-RESISTIVITY IN FE87ZR7B5AG1 AMORPHOUS ALLOY

The magnetic properties of an Fe87Zr7B 5Ag1 (at. %) amorphous alloy, which contains an additional insoluble element (Ag) in a small amount, have been investigated as a function of annealing temperatures in order to know its potential applicability as a core material used at high-frequency. As a result, a new excellent soft magnetic material with very high resistivity was developed. The amorphous alloy annealed at a relatively low temperature of Ta=300°C exhibited a very high initial permeability μi of 146 000 at 1 kHz and 2 mOe, resistivity ρRT of 4.5 μΩ m, and very low coercivity Hc of 20 mOe, respectively. The values obtained are the best ones among various kinds of Fe-based soft amorphous materials reported up to now. Furthermore, the amorphous ribbon heat treated at Ta=300°C still retained good ductility enough to endure 180°bending, which is very important from the viewpoint of processing for mass production. The phenomenon of good soft magnetic properties presumably arises from the homogenous formation of very fine α-Fe clusters in an amorphous matrix, which can be deduced from the increase of resistivity, and the reduction of magnetostriction caused by the dissolution of Zr and B into the α-Fe cluster. © 1995 American Institute of Physics.