Microstructural requirements for alumina–SiC nanocomposites

Abstract

AbstractThe relative ease with which alumina–SiC nanocomposites polish, compared with monolithic alumina, has been noted in the literature and taken to be an example of the beneficial ‘nanocomposite effect’ stemming from an apparent strengthening of the grain boundaries. The percentage of ‘polished’surface, as opposed to areas dominated by grain pullout or fracture, following grinding or polishing, therefore provides an easily obtainable figure of merit for different nanocomposite materials. A variety of alumina–SiC nanocomposites has been fabricated by co-milling commercially available powders and hot pressing in an inert atmosphere. Using variations in starting powder size and heating schedules, it has been possible to produce nanocomposites with similar matrix grain size but with different proportions of particles on the grain boundaries relative to those within the grains. The microstructures were examined using TEM and FEG–SEM, and the effect of microstructural variations on the mechanical properties...