SPS Fabrication, Microstructure and Electric Properties of TiC/Ti2AlC/TixAly in-situ Composites
SPS原位反应制备TiC/Ti2AlC/TixAly系复合材料的微观结构及其导电性能

TiC/Ti2AlC and TiC/Ti2AlC/TixAly 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/TixAly 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/TixAly composites decreased. The temperature dependence of conductivity followed the Arrhenius empirical formula in the measured temperature range.