Abstract: TiC/Ti₂AlC and TiC/Ti₂AlC/Ti_xAl_y composites were in-situ fabricated by spark plasma sintering using Ti, Al₄C₃ and graphite powders as starting materials. The phase constitution and microstructures of the composites were analyzed by XRD, SEM and HRTEM. No amorphous phase was detected at the grain boundaries. In-situ reaction and diffusion mechanism were also proposed. Through SEM images and EDS analysis of the starting powder mixtures sintered at intermediate temperatures, the intermediate phases and phase formation sequence in the sintering process can be obtained. The diffusion path in the reaction sintering always occurred along the grain boundaries or crack defects. The electric conductivities of TiC/Ti₂AlC composites were higher than that of TiC/Ti₂AlC/Ti_xAl_y composites at room temperature. The electric conductivity of TiC/40vol%Ti₂AlC was 8.83×105 S/m. With the temperature increasing, the electric conductivity of TiC/Ti₂AlC/Ti_xAl_y composites decreased. The temperature dependence of conductivity followed the Arrhenius empirical formula in the measured temperature range.

Key words: TiC, Ti₂AlC, SPS, in-situ composite, electric conductivity