Abstract: The microstructures of amorphous intergranular phase in nanocrystalline Fe_76.5-xCu_1.0Nb_xSi_13.5B_9.0(x=1,3,5 and 7) alloys, formed by partially crystallizing amorphous ribbons upon annealing, have been investigated by means of M össbauer spectroscopy. The magnetic ordering temperature T_c of the residual amorphous phase were determined by M össbauer 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.