Microstructure and mechanical properties study of slip-cast copper-alumina composites

Alumina matrix composites reinforced with metallic copper were produced and their microstructure and mechanical properties were studied. The composites were fabricated by aqueous slip casting technique, and sintered at 1500 degrees C in a hydrogen atmosphere. The samples showed low porosity and a core-skin structure with copper-free skin and a uniform spatial distribution of copper particles in the core. The addition of metallic Cu particles at low amounts in the Al2O3 matrix resulted in a small reduction in the stiffness and the hardness but augmented impact resistance. The mechanical properties of the composites were in good agreement with porosity-corrected predictions of the simple rule of mixtures, indicating that this fabrication method produces composites for which the enhanced toughness is not accompanied by a large reduction of their other mechanical properties.