PRODUCTION OF TiAl/Al۲O۳ AND TiAl/Ti۲AlC/Al۲O۳ COMPOSITES BY EXPLOSION SYNTHESIS

Thermal explosion mode of combustion synthesis was used to fabricate TiAl-Al۲O۳ and TiAl-Ti۲AlC-Al۲O۳ composites from elemental powder mixtures of TiO۲, Al and C and characterized by XRD and Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive Spectroscopy (EDS). The experimental results showed that thermite reaction of Al with TiO۲ caused TiAl-Al۲O۳ composite formation. By adding carbon powder to the thermite mixture, ternary carbide Ti۲AlC and TiAl-Ti۲AlC-Al۲O۳ composite were formed. With low carbon in thermite mixture, direct formation of Ti۲AlC without intermediate TiC was observed. After TiAl formation, Ti۲AlC precipitated from molten TiAl in the vicinity of carbon particles. SEM micrographs show that addition of carbon to thermite mixture changes the microstructure to a laminated form with plate-like grains.