Properties and microstructures of Lanxide Al2O3-Al ceramic composite materials

A study has been made of four Al2O3-Al composite materials fabricated by the directed oxidation of molten aluminum alloys. Their microstructures are described and measurements of density, coefficient of thermal expansion, thermal conductivity, hardness, elastic constants, compressive strength, flexural strength, fracture toughness, work of fracture, and thermal shock resistance are reported. Compared to a typical dense sintered Al2O3, such as Durafrax 1542, which is somewhat harder, stiffer, and stronger in compression, the new composites can be stronger in flexure, particularly at high temperatures, far tougher, and considerably more resistant to thermal shock. Attempts are made to relate their differences in properties to microstructure. (Author)