Preparation of Al2O3-TiC nanocomposite by mechano-chemical reduction of TiO2 with aluminum and graphite

Al2O3-TiC (AT) nanocomposite was synthesized by mechanical alloying (MA) of TiO2, Al and graphite powder mixture. Effect of the milling time, starting composition and heat treatment temperatures were investigated. X-ray diffraction (XRD) was used to characterize the milled and annealed powders. The morphological and microstructural evolutions were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that the formation of TiC initiates after 20 h and completes after 35 h of milling. Residual Al in the 35 h milled powder was removed by lessening its content in the initial mixture to 20 wt.%. Annealing of the 80 h milled sample at 800 °C led to the obtaining maximum micro-hardness of 16.25 GPa. Mean crystallite size of 12 nm was estimated for 35 h milled sample with 28 wt.% Al. TEM and SEM images confirmed the nanocrystalline structure with very good distribution and homogeneity of TiC and Al2O3, respectively.