AVS 50th International Symposium
    Applied Surface Science Thursday Sessions
       Session AS-ThM

Paper AS-ThM10
Auger Spectra Line Shape Study in Iron-Aluminum-Oxygen Reaction System

Thursday, November 6, 2003, 11:20 am, Room 324/325

Session: Electron Spectroscopy
Presenter: S. Nayak, University of Tennessee, Knoxville
Authors: S. Nayak, University of Tennessee, Knoxville
H.M. Meyer, III, Oak Ridge National Laboratory
N.B. Dahotre, University of Tennessee, Knoxville
Correspondent: Click to Email
Normalized intensity-kinetic energy Auger electron spectra were collected for different state of iron and aluminum. The standards and the samples were ion-sputtered and monitored until they attained a stable spectrum. The line-shape of spectra corresponding to iron in standard pure iron, iron oxides (Feo, Fe@sub 2@O@sub 3@ and Fe@sub 3@O@sub 4@) and Fe@sub 3@Al were compared. The spectra non-metallic irons exhibit distinctly different line shape than that of metallic iron. This change in line shape was also accompanied by shift in peak. Similarly, spectra corresponding to aluminum were collected for pure aluminum, Al@sub 2@O@sub 3@ and Fe@sub 3@Al. There is a distinct change in shape of line both in the case of aluminum and iron. The information was used to study the non-equilibrium two phenomena: (1) laser-induced reaction coating of iron oxide on aluminum alloys and (2) mechanical alloying of iron oxides and aluminum. In laser coating, the high rate of heating and cooling freeze-in the reaction between iron oxides and aluminum. Elemental mapping using the shift in peak position provides information about reaction mechanism. The spectra obtained from laser coating sample has a shape intermediate between purely metallic and oxidized iron and aluminum. The mechanically alloyed powder exhibited spectra line-shape commensurate with the extent of reaction. By choosing the window of kinetic energy, it was possible to map Fe and Al in combined and metallic state distinctly. Al@sub 2@O@sub 3@ and Fe@sub 3@Al were formed during the reaction between iron oxide and Al. The intermediate (frozen-in) reaction products showed gradual change of peak position and line shape from metallic to oxidized state for Fe and Al. The concept of line shape and peak shift was used to successfully study the reaction and its mechanism.