Amorphous Fe _63.5 Cr ₁₀ Si _13.5 B ₉ Cu ₁ Nb ₃ ribbon samples have been prepared by melt spinning. The addition of Cr to a FINEMET-type alloy decreases the Curie temperature of the amorphous matrix and also modifies the alloy crystallization temperature. The evolution of the microstructure during crystallization has been analyzed by means of x-ray diffractometry and transmission electron microscopy. An interesting dependence of the intensity of the amorphous diffraction halo was observed for temperatures below 818 K, where a large fraction of glassy phase was still present in the sample. The evolution of the coercivity with annealing temperature for various measurement temperatures has also been studied and, in conjunction with the microstructural observations, is interpreted within the framework of the two-phase theory for nanocrystalline materials. © 2002 American Institute of Physics.