Application of FTIR spectra for evaluating interfacial reactions in metal matrix composites
2008
Kúdela, S. Jr | Oswald, S | Kúdela, S | Wetzig, K
Manufacturing of Saffil/MgLi metal matrix composites by the melt infiltration process is accompanied by extensive interfacial redox reaction between δ-Al₂O₃ fibers (Saffil) and lithium. The present paper deals with the Fourier transform infrared spectroscopy examination of Saffil fibers isolated from Mg-8 wt% Li alloy by the bromine/methylacetate agent focusing on the insertion of Li⁺ ions into δ-Al₂O₃ and their influence on water adsorption. Insertion of Li⁺ into δ-Al₂O₃ is monitored by gradual change of Al-O stretching bands (400-900 cm⁻¹) towards more simple patterns of a spinel-like product assigned as δ(Li) which transforms to LiAl₅O₈ during subsequent annealing. Rapid increase in the water adsorption with increase in Li content, indicated by the changes in H-O-H bending (about 1,650 cm⁻¹) and O-H stretching (about 3,500 cm⁻¹), is connected with the ionicity of the δ(Li) phase, which attracts polar water molecules.
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