Fabrication of Ti2AlN ceramics with orientation growth behavior by the microwave sintering method

Porous Ti2AlN ceramic, which was measured to be 3.23 g/cm3 about 74.9% of its theoretical value, was successfully synthesized and simultaneously consolidated from starting raw materials of Ti, Al, and TiN powders with a near-stoichiometric molar ratio of 1:1.03:1 by a microwave sintering method at 1200 °C for 30 min in an argon atmosphere. When sintered at 1200 °C for 1 h, the Ti2AlN grain showed a preferred growth behavior along the c-axis in the final ceramic, as shown by the results of an X-ray diffraction study. The Lotgering orientation factor on the surface of as-sintered Ti2AlN ceramic was as high as f(0 0 ℓ) = 0.598. A traditional synthesis method in a quartz tube furnace was also applied to synthesize the materials under the same conditions, but this did not result in similar preferred grain growth phenomenon. Factors affecting the orientation were discussed, and an underlying growth mechanism was suggested. Also, a dense Ti2AlN sample was obtained by re-sintering the porous Ti2AlN sample using a spark plasma sintering method. As a result, the orientation was maintained, and the density was measured to be 4.21 g/cm3, which reached 97.6% of its theoretical value.