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 micros tresses in each phase and the stress fluctuations in the matrix were e valuated from a combination of X-ray reflection shift and line broaden ing analysis. The measured average microstresses show good agreement w ith those calculated theoretically from a simple model. The average mi crostress in the matrix increases with the SiC content while the fluct uations of the stress field decrease. In effect, the mean dislocation density in the alumina matrix increases with the SiC volume fraction w ith more dislocations for-ming networks and subboundaries, as was conf irmed by transmission electron microscopy.