M O ¨SSBAUER STUDY OF AMORPHOUS INTERGRANULAR PHASE IN NANOCRYSTALLINE SOFT MAGNETIC Fe 76.5- x Cu 1.0 Nb x Si 13.5 B 9.0 ALLOYS

The microstructures of amorphous intergranular phase in nanocrystalline Fe 76.5- x Cu 1.0 Nb x Si 13.5 B 9.0 (x=1,3,5 and 7) alloys, formed by partially crystallizing amorphous ribbons upon annealing, have been investigated by means of M o ¨ssbauer spectroscopy. The magnetic ordering temperature T c of the residual amorphous phase were determined by M o ¨ssbauer thermal scan method. The regular variation of crystallization temperature, magnetic ordering temperature and average hyperfine magnetic field of the amorphous alloys with Nb content were observed. The effect of nanocrystalline grains on amorphous intergranular phase through magnetic interactions and the effect of Nb in these alloys were analysed.