We used the nuclear magnetic resonance technique to study the evolution of the structural and magnetic properties of Fe-based melt-spun ribbons of Fe73.5Cu1Nb3Si13.5B9, Fe73.5Cu1Nb3Si18.5B4, and Fe86Zr7Cu1B6, as-cast and annealed at 500, 540, and 430 °C, respectively. Experiments were carried out at 4.2 K and zero-applied magnetic field, and in a controlled radio-frequency (rf) field. This type of measurement allows us to observe B and Nb sites, and makes it possible to distinguish signals associated with regions of different magnetic hardnesses. The results exhibit a high dependence of the spectra on rf power. For Fe–Si-based alloys, we observe well-defined 93Nb resonance signals from three distinct sites according to the concentration of Fe atoms in their neighborhood. In the Fe73.5Cu1Nb3Si18.5B4 spectra we also observe a peak around 34 MHz, connected to the 11B resonance in different Fe–B compounds, which remains as the rf power decreases, suggesting that the signals come from atoms inside a soft magnetic region. As for the Fe–Zr alloy, we also observe a peak around 36 MHz, identified as the 11B resonance, and a broad line around 62 MHz.© 2002 America- n Institute of Physics.