MOSSBAUER STUDY OF ISOTHERMALLY ANNEALED AMORPHOUS FE-NB-CU-SI-B ALLOYS

Amorphous ribbons of Fe73.5Nb3Cu1Si13.5B9 have been annealed above the crystallization temperature. Annealed samples consisted of crystallin e and amorphous phases in a wide temperature range. Two samples of dif ferent thicknesses of 33 mum and 27 mum were isothermally annealed at a temperature of 545-degrees-C from 0.5 to 5 h in a vacuum furnace. Th e amount of crystalline phase increases rapidly in the ticker sample. The crystalline part of the Mossbauer spectrum consists of four sharp sextets which can be assigned to a DO3-structure FeSi alloy. After 700 -degrees-C annealing the amorphous phase was not observed and the crys talline phase consisted of the DO3-structure FeSi alloy, paramagnetic FeNbB and presumably Fe23B6 and Fe3SiB2.