Formation of Al2O3 during heating of an Al/TiO2 nanocomposite powder

The solid-state reactions between Al and TiO2 that occur during heating an Al/TiO2 nanocomposite powder produced using high-energy mechanical milling have been studied using thermal analysis, x-ray diffractometry (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) in combination with compositional microanalysis. It has been found that Al and TiO2 react in the temperature range from 650 to 800 degrees C, forming Al3Ti, but XRD analysis, SEM examination, and detailed TEM characterization of the powder particles heated to 800 degrees C show that the expected Al2O3 does not form. However, alpha-Al2O3 particles form during heating from 800 to 1000 degrees C. The possible reasons for the time gap between formation of Al3Ti and Al2O3 are discussed.