RESIDUAL-STRESSES IN ALUMINA-SIC NANOCOMPOSITES

Residual stresses in an alumina-SiC particulate composite were studied as a function of SiC content by X-ray diffraction. The average microstresses in each phase and the stress fluctuations in the matrix were evaluated from a combination of X-ray reflection shift and line broadening analysis. The measured average microstresses show good agreement with those calculated theoretically from a simple model. The average microstress in the matrix increases with the SiC content while the fluctuations of the stress field decrease. In effect, the mean dislocation density in the alumina matrix increases with the SiC volume fraction with more dislocations for-ming networks and subboundaries, as was confirmed by transmission electron microscopy.