Lamellar structure and effect of Ti2AlC on properties of prepared in-situ TiAl matrix composites

TiAl matrix composites, reinforced with varying Ti2AlC content levels, were synthesized by vacuum arc melting by use of Ti, Al and graphite powders as raw materials. The effects of varied Ti2AlC content from 0 to 100 mol% on the phases, microstructures, fracture behaviors and mechanical properties of resulting products were analyzed. Phase transformation was characterized by X-ray diffraction (XRD) and microstructures were measured by scanning electron microscopy (SEM), equipped with energy-dispersive spectroscopy (EDS). Results show that the products are composed primarily of TiAl, Ti3Al, Ti2AlC and small amounts of TiC. The unreacted TiC phase is due mainly to evaporation of Al. The Vickers hardness value of TiAl matrix composite was increased by adding Ti2AlC, while the TiAl/Ti2AlC composite fracture behaviors were improved in terms of crack deflection, trans-lamellar cracking and extraction of carbide reinforcements.