Infrared reflectance spectra of oxide films on aluminum-magnesium alloys

Infrared reflectance spectra of oxide films on hot rolled 3004 and 5182 aluminum alloy surfaces indicate the presence of two types of magnesium-doped aluminum oxide. Heating the samples to 350°C or more causes shifting and broadening of the 900 cm −1 aluminum-oxygen absorption band for 3004 metal, and the appearance of a magnesium-oxygen absorption band at 670 cm −1 in the reflectance spectra of both 3004 and 5182 metal. Reflectance spectra of the surfaces on cold rolled 3004 and 5182 metal show no absorption bands on unheated samples. However, results from time-temperature studies indicate that further oxidation of these samples is more rapid than in hot rolled samples. The oxides formed on cold and hot rolled 5182 metal are similar, while cold rolled 3004 metal initially forms an oxide which differs from that on hot rolled 3004 metal, exhibiting a broader absorption band at approximately 850 cm −1.