FLEXURAL STRENGTH OF IN SITU REACTION PROCESSED Al₂O₃-Al₃Ti-Al COMPOSITES

Fully dense Al₂O₃-Al₃Ti-Al composites were in situ reaction processed by combining squeeze casting technique with combustion synthesis utilizing the reaction between TiO₂ and pure Al. The in situ reaction formed spherical Al₂O₃ particles with a size of 0.1μm to 1μm are uniformly distributed in the matrix. The composites possess high flexural strength (410～490MPa) and elastic modulus (156～216GPa). With increasing content of Al in the composite, the bending strength begins to increase slightly and then decreases when the volume fraction of Al exceeds 40%. The elastic modulus of the composites decreases with increasing content of Al. The high flexural strength of the in situ composites is mainly attributed to the dispersion strengthening of fine Al₂O₃ particles and Al₃Ti phase.