Evaluation on microstructure and dissolution behavior of SiC-AlN composites fabricated by SPS process

High-density SiC-AlN composites (50:50 in mol) were fabricated from powder mixtures of SiC and AlN by SPS process in the temperature range of 1800-2100°C. Relative densities of the composites increased with increasing firing temperature. It revealed that the mixed phases of 3C and 2H formed at 1800°C, 1900°C and 2000°C, and only 2H phase formed at 2050°C and 2100°C. The sintering of SiC and AlN particles proceeded hardly at 1800°C. The densely sintered SiC-AlN composites were obtained above 1900°C. At 1900°C and 2000°C, 3Css (β-SiC/AlN solid solution) and 2Hss (α-SiC/AlN solid solution) were found, in which Si-rich 2Hss and Al-rich 2Hss existed at 2000°C. Homogeneous SiC-AlN composites were obtained with grain-growth at 2100°C.