The crystallization behavior and sintered texture of amorphous Si3N4-BN composite powder were investigated in the range 1200-1800degreesC with sintering aids from the Y2O3-Al2O3 and Y2O3-TiO2-AlN systems. With the Y2O3-Al2O3 system, no crystalline phase was observed at 1200degreesC. alpha- and beta-Si3N4 were detected by XRD at 1400degreesC, and alpha-Si3N4 was transformed to beta-Si3N4 and h-BN appeared at 1600-1800degreesC. On the other hand, with the Y2O3-TiO2-AlN system, a small peak of TiN was detected at 1200degreesC. Si2N2O was detected with alpha- and beta-Si3N4 at 1400degreesC. At 1600-1800degreesC, beta-Si3N4 and h-BN were detected and Si2N2O disappeared. In the sintered texture at 1800degreesC, flaky BN particles with a length of about I gm were observed in an equiaxed Si3N4 grain matrix in the Y2O3-Al2O3 system, whereas rod-like Si3N4 grains with a length of 2-3 mum and flaky BN particles with a length of about 1.5 mum were observed in the Y2O3-TiO2-AlN system.

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