Results are reported from small-angle neutron scattering (SANS) and Mossbau
er spectrometry measurements on four Ni3Fe materials: nanocrystalline mater
ial prepared by mechanical attrition, nanocrystalline material after an exp
osure to 4K, nanocrystalline material after a heat treatment of 100 degrees
C for 10 days, and a control sample composed of large crystals. Scattering
from the nanocrystalline materials after thermal treatments showed changes
in the intensity and the slope of both the nuclear and the magnetic scatte
ring profiles of the SANS measurements. The Mossbauer spectra from the nano
crystalline samples showed changes in the hyperfine fields associated with
grain-boundary atoms. The changes induced by cryogenic exposure and anneali
ng at 100 degrees C were somewhat different but were consistent with a shar
per density gradient between the crystalline region and the grain-boundary
region. Some grain-boundary atoms in mechanically attrited Ni3Fe are in ene
rgetically unfavourable positions, and move into new positions during these
low-temperature treatments.