Additional Effect of Yttria or Magnesia on Densification and Mechanical Properties of Titanium Carbide Whisker/Alumina Composites

Twentey vol% titanium carbide whisker/alumina composites added with 0.5 mass% yttria or 0.5 mass% magnesia were fabricated by hot-pressing at 1400-1700°C under 30MPa for 30 min. Their densification and mechanical properies were compared to those with no addition. Little effect of these addition on the densification was observed, and each composite had the highest density at a sintering temperature of 1600°C. The addition of yttria increased the room temperature and the high temperature bending strength, due to the existence of yttrium aluminum garnet (Y3Al5O12). The magnesia addition also improved the room temperature strength although the effect was less than that in the case of yttria addition. These addition was ineffective for improvement of hardness and fracture toughness of the composites.