Reaction synthesized Al2O3-based intermetallic composites

Abstraet-Intermetallics-reinforced Al 2 O 3 composites have been fabricated by reaction sintering compacts of intensively milled powder mixtures containing either metal oxides and Al or elemental metals, Al and Al 2 O 3 . During carefully controlled heat-treatment in non-oxidizing atmosphere. the metal oxides, for instance TiO 2 Fe 2 O 3 and Nb 2 O 5 , are reduced by Al to form the respective aluminides (Ti x Al y Nb x Al y ), Alternatively, aluminides can also be formed through reaction between Al and elemental metals (e.g. Fe), By adding Al 2 O 3 to the starting mixture, the intermetallic ceramic ratio of these alumina-alsiminide alloys (3A) can be adjusted within a wide range. At intermetallic volume fractions> ∼20 vol.%, both phases are continuous, exhibiting a microstructure similar to that of products of directed metal oxidation or reactive metal penetration processes. In this paper, systems based on Ti x Al y , FeAl and NbAl 3 are emphasized. The principles of the reaction synthesis process and the influence of the processing parameters on microstructural development and mechanical properties are described.