NANOCRYSTALLIZATION AND MAGNETIC-PROPERTIES OF FE56CO7NI7ZR2M8B20 (M = NB OR TA) GLASSY ALLOYS

Glassy alloys with a wide supercooled liquid region before crystalliza tion were found in melt-spun Fe56Co7Ni7Zr2M8B20 (M = Nb or Ta) alloys. The temperature interval of the supercooled liquid region defined by the difference between glass transition temperature (Tg) and crystalli zation temperature (T-x), Delta T-x(=T-x-T-g) is about 60 K for these alloys. The crystallization occurs through distinct two stages. The cr ystallization behavior seems to reflect the existence of Fe-2(M,Zr) ph ase resulting from the weaker bonding nature of Fe-M pair as compared with Fe-Zr pair. Good soft magnetic properties are obtained in the ann ealed state for 300s at 800K below T-g for these alloys. Saturation ma gnetization (I-s), coercive force (H-c) and effective permeability (mu (e)) at 1 kHz are about 0.8T, 2A/m and 18000, respectively. The above- mentioned glassy alloys,with wide supercooled liquid region and good s oft magnetic properties heave a strong possibility of producing soft m agnetic bulk amorphous alloys. (C) 1998 Acta Metallurgica Inc.