Investigation of Ti2AlC formation mechanism through carbon and TiAl diffusional reaction

Ti2AlC formation mechanism with carbon and TiAl alloy as reactants at 1000-1200 °C have been investigated through Raman spectrometer and transmission electron microscope (TEM). Reaction products TiCx and Ti2AlC are confirmed. Full width at half height (FWHH) of Ti2AlC Raman peak is used to characterize crystallinity, which indicates better perfection of Ti2AlC grains near TiAl area and with higher reaction temperature. Variations of TiCx microstructure, especially stacking faults(SF) and nanotwins, are observed by TEM along reaction layer. Ti2AlC lattice uniformity of different reaction temperature is also confirmed by TEM, which is consistent with Raman result. TiCx is believed first formed through reaction between TiAl and C. With help of carbon vacancy, Al-doped TiCx SF and nanotwin can be formed under hot pressing, which becomes the basal frame of Ti2AlC.