A set of Fe-based amorphous alloys,Fe93−x−yZr7BxCuy,withx=4,6, 8, or 12, andy=0or 2 has been systematically characterized in their ability to form nanocrystalline, magnetically soft material via annealing in the range of 430–600 °C. Conventional Mo¨ssbauer spectroscopy is used to follow the degree of bcc-Fe formation as well as changes in the hyperfine field distribution of the amorphous phase as a function of anneal temperature. Copper plays a strong role in the bcc-Fe formation forx=12but less of a role forx=8and 6. Unconventional Mo¨ssbauer studies utilizing radio frequency (rf) fields provide information on the soft magnetic nature of the alloys by observing the degree of rf-induced collapse of the hyperfine fields. The Mo¨ssbauer experiment in which the rf collapse and rf sideband effects are used allows the soft nanocrystalline bcc phase to be distinguished from magnetically harder microcrystalline &agr;-Fe. The rf Mo¨ssbauer technique, being particularly sensitive to the magnetic anisotropy, provides information on the anisotropy fields and hence on the grain size distribution. X-ray diffraction (XRD) is used to estimate the bcc-Fe grain size based on the diffraction peak linewidths. Average grain sizes of 5–14 nm are found for 500–550 °C annealed specimens where smaller grain sizes are always observed fory=2compared toy=0for fixedx.Small-angle x-ray scattering is also used to study the grain size and this method yields sizes in the range from 3 to 7 nm, consistently almost a factor of 2 smaller than those from the XRD line broadening. This discrepancy is attributed to the difference in the regions of the 20-&mgr;m-thick ribbons probed by the two methods. ©1997 American Institute of Physics.