PREPARATION AND SOFT-MAGNETIC PROPERTIES OF FE-BASED BULK AMORPHOUS-ALLOYS

This review deals with our recent development of Fe-based bulk amorpho us alloys with soft magnetic properties. Multicomponent Fe-(Al,Ga)-(P, C,B,Si) and Fe-(Co,Ni)-(Zr,Nb,Ta)-B alloys are amorphized in the bulk form with diameters up to 2 and 6 mm, respectively, by copper mold cas ting and the largest temperature interval of the supercooled liquid re gion before crystallization is 67 and 88 K, respectively. These bulk a morphous alloys exhibit good soft magnetic properties, i.e., high satu ration magnetization (I-s) of 1.1 to 1.2 T and low coercivity (H-c) of 2 to 6 A/m. The saturated magnetostriction (lambda(s)) and Curie temp erature (T-c) are in the range of 20-30X10(-6) and 580-605 K, respecti vely, for the former system and 10-14X10(-6) and 447-594 K, respective ly, for the latter system. The effective permeability (mu(e)) at 1 kHz is 7000-15000 for the Fe-(Al,Ga)-(P,C,B,Si) amorphous ribbons and 150 00-25000 for the Fe-(Co,Ni)-(Zr,Nb)-B amorphous ribbons. In comparison with Fe-Si-B amorphous ribbons, it is characterized that the present alloys have lower H-c and higher mu(e) resulting from lower lambda(s). The easy formation of bulk Fe-based amorphous alloys with good soft m agnetic properties indicates the possibility of future development as a new type of soft magnetic material.