Effect of Milling Intensity of TiO2-Al Powder Mixture on Microwave Synthesis of TiAl/Al2O3 Composite

In this research, TiAl/Al2O3 composite was synthesized from mechanically activated TiO2-Al powder mixtures using microwave heating. The powder mixtures were heated in a microwave oven after milling and pressing into cylindrical tablets. The effect of mechanical activation intensity was evaluated on the ignition time and the resultant reaction products. XRD and SEM analysis were used for evaluation of the synthesized samples. Moreover, the volume percent of the formed phases was calculated from XRD patterns using Maud software. The results confirmed that the composites mainly consist of TiAl and dispersed Al2O3 particles. The dominant phase is Al2O3 with 65-75 vol.% and the amount of TiAl phase varies from 18 to 30 vol.%. The results revealed that with increasing the intensity of activation, the ignition time first decreased and then increased. At optimum condition with an ignition time of 27 s, the composite structure is more uniform and less porous and it consists of 23.2% TiAl and 69.6% Al2O3.