Microstructure design and processing of aluminum -alumina composites

Much of the prior research in the field of ceramic-metal composites has been conducted without due regard to composite microstructure. Processing difficulties have often prevented the production of composites with controlled microstructural features. Methods designed to surmount the various processing barriers and enable a high degree of microstructural control have been developed in this study. Fugitive phase processing and partial sintering techniques have been employed to tailor the porosity of Al2O3 preforms that were subsequently infiltrated with molten Al. Methods were also developed to coat the internal surfaces of porous Al2O3 preforms with reactive materials that facilitated infiltration of the otherwise non-wetting Al melts. Laminates, gradients and homogeneous composites with controlled microstructures have been produced with these techniques. Elasticity, wave attenuation, as well as compressive failure and bending response have been investigated. Phase fraction seems to most severely influence elastic properties and wave attenuation in homogenous composites, whereas ceramic contiguity and flaw distributions (leading to enhanced plasticity) dictate the mechanical response in compression and bending