The location of diffused 57Co atoms in monocrystalline and polycrystalline samples of Fe72Al28 was investigated by means of Mössbauer spectroscopy. A detailed analysis of the spectra showed that a large fraction of the atoms which diffused along the grain boundary interfaces occupied positions that were different to those in the bulk. During volume diffusion, there was a strong preference for the usual Fe site in the D03 superstructure, which had four Al atoms in the nearest-neighbourhood positions. No sign of 57Co atoms on the B or D sites of the D03 superstructure was found. A component which represented 57Co atoms placed at grain-boundary interfaces was identified in spectra from the polycrystalline sample. The intensity of this component changed with annealing time, in agreement with a model which treated the grain boundary as being a source of 57Co atoms for volume diffusion.

Site Preference of 57Co in Fe72Al28 after Grain Boundary Diffusion. O.Schneeweiss, S.Havlícek: Materials Science Forum, 1999, 294-296, 577-80