Determination of amorphous interfacial phases in Al2O3/SiC nanocomposites by computer-aided high resolution electron microscopy

The analysis of thin amorphous layers in transmission electron microscope i maging has always been rendered difficult by the sample geometry conditions which must be met in order to single out the electronic scattering due to the amorphous phase from the overlapping crystalline diffraction fringes. T his is the case of Al2O3/SiC nanocomposites in which spherical fine SiC par ticles are entrapped into the Al2O3- matrix grains. The spherical geometry of the SiC dispersoids involves a circular phase boundary in the thin foil which is hardly examined by conventional high-resolution techniques. In thi s paper an alternative technique of computer-aided high-resolution microsco py is proposed for imaging the presence of non-crystalline third phases at the interface of the alumina matrix and the silicon carbide nanosized parti cles in Al2O3/SiC nanocomposites. Implications regarding the effect of the observed layer on some toughening mechanisms proposed in literature for thi s materials are included. (C) 2001 Acta Materialia Inc. Published by Elsevi er Science Ltd. All rights reserved.