Gradient Structure of Ti-Al-C Ternary Carbide Prepared by Hot-pressing Sintering

X-ray diffraction （XRD） analysis on different polished surfaces normal to the hot pressing direction reveals that the phase compositions of the polished surfaces from the outside to the inside are pure TiC, Ti3AlC2+TiC, pure Ti3AlC2 and Ti2AlC+Ti3AlC2, no matter elemental powder or TiC is used as raw materials. It is found that ternary-layered carbide Ti2AlC samples synthesized at 1500 ℃ by hot-pressing sintering are inhomogeneous and have a gradient structure.Electron probe X-ray micro-analysis （EPMA） indicates that the Al content along the hot pressing axis is parabolic, it is the highest in the center and the lowest at the both ends, while the Ti content is constant along the axis. The experimental result reveals that the evaporation of Al in samples in an open system during hot pressing sintering results in a gradient structure.