In-situ hot pressing/solid-liquid reaction synthesis of bulk Cr2AlC

Single-phase bulk Cr2AlC, a non-Ti-containing carbide with superior expected properties, was successfully fabricated by in-situ hot pressing/solid-liquid reaction process. The reaction process was investigated using differential scanning calorimetry. The products were characterized using X-ray diffraction and scanning electron microscopy. Four distinguished stages of the reactions from Cr, Al, and C elemental powders were discussed. The obtained X-ray diffraction data are in good agreement with calculated ones and those from JCPDS card No. 29-0017. A new set of Xray diffraction data. comprising reflections, 2 theta, and intensities of Cr2AlC is presented. Lattice parameters obtained by Rietveld XRD refinement of Cr2AlC are a = 2.858 angstrom and c = 12.818 angstrom, respectively. The measured Vickers hardness of the as-synthesized Cr2AlC is 5.5 +/- 0.4 GPa, which is twice that of Ti2AlC. CrAlC displays excellent oxidation resistance. The parabolic rate constant of Cr2AlC was decreased by 3 - 4 orders of magnitude compared with those of Ti3SiC2 at 1200 degrees C.