Effects of TiN Particle Size on Mechanical Properties of Si3N4/TiN Particulate Composites

Abstract
Si3N4/10vol% TiN particulate composites with six TiN particle size distributions (average size: 0.3-13.6μm) were sintered at 1850°C for 4h in 0.9MPa N2 atmosphere, and Young's modulus, fracture toughness and microstructure of the composites were examined. Although all the composites were densified up to >98% theoretical density, Young's modulus of the composites with larger TiN particles decreased due to the pre-existing microcracks. Fracture toughness of the composites showed a maximum value at the particle size of TiN of about 4μm, which is smaller than the predicted critical size. It is suggested that the presence of the grain-boundary phases in the composite favors the formation of microcracks at smaller TiN particles.

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