Fabrication of Al₂O₃/W Nanocomposites

Mechanical properties and microstructure of Al₂O₃/W composites have been investigated. These composites were fabricated by hot-pressing the mixture of γ - or α-types of alumina(Al₂O₃) and fine tungsten(W) powders. In these composites, the fine W particles were located both within Al₂O₃ matrix grains and at grain boundaries. The fracture strength of Al₃O₃/5vol%W composites sintered at 1400°C was 700MPa, which is approximately 1.6 times higher than that of the monolithic Al₂O₃ that prepared under the same conditions. But the strength decreased with increasing sintering temperature. Although the interactions between clacks and W dispersions were partly observed, the fracture toughness was not significantly enhanced. It is supposed that the effects of nano-structure did not sufficiently act on the mechanical properties of the composites because the grain boundary of Al₃O₃, where large W particles are located, was not strengthened by the dispersions.