Mechanical Properties and Microstructure of Whisker-Reinforced Alumina–30 vol% Glass Matrix Composite

High-density whisker-reinforced composites of an alumina-30 vol% glass matrix material were produced by hot-pressing in the temperature range 1350° to 1400°C in air. Significant improvement was observed in the strength of composites containing 15 vol% SiC whiskers, up to ～550 MPa, but with only a small effect on the fracture toughness. In composites containing Si₃N₄ whiskers, no reinforcement was achieved. Transmission electron microscopy showed the formation of a protective layer of amorphous silica on the SiC whiskers, while the Si₃N₄ whiskers were found to react with the matrix. The mechanical properties were related to the microstructure and the density of the samples.