Fe-based soft magnetic amorphous alloys with a wide supercooled liquid region

Abstract

Amorphous alloys with a wide supercooled liquid region (ΔTx) before crystallization were formed in the Fe56Co7Ni7Hf8M2B20 (M=Nb, Ta) alloys by melt spinning. The ΔTx which is a critical factor of glass-forming ability, increases to large values exceeding 90 from 82 K by the addition of 2 at. % M, and the largest ΔTx value is larger by about 10 K than the largest value for recently reported (Fe,Co,Ni)–Zr–M–B alloys. By the addition of the M metals, magnetic properties also changed. Good soft magnetic properties were obtained for the alloys annealed for 300 s at 800 K. The saturation magnetization (Is), coercive force (Hc), and effective permeability (μe) at 1 kHz are, respectively, 0.71 T, 1.0 A/m, and 16 700 for the M=Nb alloy and 0.76 T, 1.0 A/m, and 15 600 for the M=Ta alloy. The finding of the Fe-based amorphous alloys exhibiting simultaneously the wide supercooled liquid region before crystallization and the good soft magnetic properties seem to enable the future development of a new ferromagnetic bulk amorphous alloy.