Application of FTIR spectra for evaluating interfacial reactions in metal matrix composites

Manufacturing of Saffil/MgLi metal matrix composites by the melt infiltration process is accompanied by extensive interfacial redox reaction between delta-Al(2)O(3) 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 delta-Al(2)O(3) and their influence on water adsorption. Insertion of Li(+) into delta-Al(2)O(3) 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 delta(Li) which transforms to LiAl(5)O(8) 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 delta(Li) phase, which attracts polar water molecules.