⁵⁷ Fe Mössbauer spectrometry is used to elucidate the structural arrangement and nature of hyperfine interactions in amorphous and nanocrystalline forms of Fe ₈₀ M ₇ B ₁₂ Cu ₁ ( M=Mo , Nb, and Ti) alloys. Paramagnetic at room temperature as-quenched M=Mo amorphous alloy shows a distribution of quadrupole splitting (T_C=265  K ). After partial crystallization, a wide range of hyperfine interactions is observed in the residual amorphous matrix of all samples. The hyperfine field distributions corresponding to the amorphous phase and interfacial zone provide a quantitative basis for a design of topography of hyperfine interactions. Closer inspection of magnetic interactions is made by the help of unconventional radio frequency (rf) Mössbauer technique. The rf Mössbauer results show that the nanocrystalline Fe phase has a larger anisotropy than that of the parent amorphous phase. Conventional magnetic measurements, differential scanning calorimetry, x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy experiments are employed to provide complementary information. © 1999 American Institute of Physics.