dUniversity of Illinois, Center for Microanalysis of Materials, Urbana IL 61801, USA

Rapidly solidified ribbons of AlSi11Fe2 are obtained by melt spinning in ambient atmosphere. Auger Electron Spectroscopy (AES) combined with sequential removing of layers by argon ion sputtering is used for analyzing the surface of as-cast specimens. Formation of (Al-Fe-Si)-complexes and fine silicon (about 10 nm in size) particles, both with strong tendency to accumulate at the surface and interfaces of submicron aluminum grains, is assumed by AES results and SEM observations. However, the stoichiometry of Fe-containing complex is not possible to determine from these methods. In an attempt to reveal the structure, X-Ray Powder Diffraction (XRPD) is used. It gives an evidence of crystallized Fe-containing phase only for heated samples at higher temperatures (above 680K). The small peaks visible on the diffraction patterns are assigned to aluminum iron silicide (Al₃FeSi). For as-cast sample this phase is not registered. To obtain the short-range structure of Fe-containing phase, which appeared to be fully "amorphous" for XRPD, Mossbauer spectroscopy is applied. Quadropole-split doublet spectrum for as-cast sample points on formation of definite nearest neighbor configuration around the iron atom. The relatively small line width is proposed to indicate formation of clusters and/or aggregates. Absence of drastic changes in spectra and Mossbauer parameters for thermally treated specimens up to 780K demonstrates that the initially formed in as-cast samples Fe-containing complex does not change its structure during heating. Increasing of f΄ factor (relative absorption line intensities) could be explained with crystal growth in the heated samples. Joint application of surface and structure sensitive techniques in this study gives the opportunity to analyze the nanoscale phenomena from initial clustering at surface and interfaces to phase formation during thermally activated structure development.