The study of homogeneity of the hexagonal Ti3AlC2 phase with inclusions of the titanium carbide.

Maps of spatial distributions of Ti, Al, and C on two surfaces of the Ti₃AlC₂ hexagonal phase (the so-called MAX phase) with inclusions of the TiC phase and Al₂O₃ were obtained by means of the energy-dispersive X-ray spectroscopy. Volume fractions of phases were 0.848, 0.107, and 0.045, respectively. The sample was cut from the synthesized tablet. One of the analyzed surfaces of the sample was the free outer surface of the tablet (surface 1), and another surface was the cut (surface 2). Histograms of the concentration distributions of elements were plotted. For both surfaces, histograms of all elements have Gaussian forms with mean values of about their stoichiometric concentrations in Ti₃AlC₂ and TiC phases. Histograms for the carbon have maxima at 34–36 at. %, which is close to the stoichiometric content of the carbon in the Ti₃AlC₂ MAX phase (33 at. %), and at about 50 at. % that corresponds to the stoichiometric concentration of the carbon in the TiC phase. However, Gaussian standard deviations from these mean values are large (up to 7 at. %), which proves the existence of th vacancies and interstitials of the carbon in phases. The histogram for the aluminum on surface 1 has an additional distribution near zero value of the concentration, and the histogram for carbon on surface 2 has an additional distribution near 27.7 at. %. Both found particularities can be explained by supposing that the outer surface of the original tablet cools down more rapidly than its inner parts. [ABSTRACT FROM AUTHOR]