Fabrication and mechanical properties of particle dispersed Al-Al2O3 composite materials.

Aluminum alloys containing Al2O3 particles with 0.15 to 3.0μm in diameter were prepared by means of squeeze casting and extrusion. Mechanical properties were evaluated at room and elevated temperatures. It was difficult to make the composite materials containing Al2O3 particles smaller than 0.15μm by the ordinary squeeze casting. It became feasible to make Al-Al2O3 composite material by the addition of gas collected area at upper part of the preform with 0.015μm Al2O3 particle or the addition of vent hole at the bottom of the casting mold. The hardness and interstice fraction increased with increase in volume fraction of Al2O3 particle from 15% to 40%, and the heat resistance was improved. The tensile strength at 300°C was 22kgf/mm2 for the composite contaning 30vol% of Al2O3 particles with a diameter of 0.3 μm. The finer the particle size, the higher became the hardness and the tensile strength at room temperature.