Neutron Diffraction Measurements of the Residual Stresses in Al₂O₃‐ZrO₂ (CeO₂) Ceramic Composites

High‐resolution neutron powder diffraction was used to study the residual stresses in Al₂O₃‐ZrO₂ (12 mol% CeO₂) ceramic composites containing 10, 20, and 40 vol% ZrO₂ (CeO₂). The diffraction data were analyzed using the Rietveld structure refinement technique. The analysis shows that for all samples, the CeO₂‐stabilized tetragonal ZrO₂ particles are in tension and the Al₂O₃ matrix is in compression. For both the ZrO₂ particles and the Al₂O₃ matrix, the average lattice strains are anisotropic and increase approximately linearly with a decrease in the corresponding phase content. It is shown that these features can be qualitatively understood by taking into consideration the thermal expansion mismatch between the ZrO₂ and Al₂O₃ grains. Also, for all composite samples, the diffraction peaks are broader than the instrumental resolution, indicating that the strains in these samples are inhomogeneous. From an analysis of the refined peak shape parameters, the average root‐meansquare strain, which describes the distribution of the inhomogeneous strain field, was determined. Finally, the average residual stresses were evaluated from the experimentally determined average lattice strains and compared with recent results of X‐ray measurements on similar composites.