Deformation bands in ceria-stabilized tetragonal zirconia/alumina: I, measurement of internal stresses

The residual stresses within a deformation band in a ceria-stabilized tetragonal zirconia/alumina (Ce-TZP/Al2O3) ceramic composite are measured by piezo-spectroscopy, in the zirconia phases from their Raman spectra and in the alumina phase from its Cr3+ fluorescence. The concentrations of monoclinic zirconia across the deformation band are obtained from Raman spectra recorded from locations across the band. These measurements show that the deformation bands are associated with a localization of the tetragonal-to-monoclinic transformation and that although the overall residual stress in the bands is compressive, the tensile stress in the tetragonal zirconia phase is enhanced. The experimental data are compared with the predictions of a stochastic theory for three-phase materials and with models for the stress distribution within a deformation band. The region ahead of the deformation band is subject to an additional, superimposed tensile stress whose magnitude compares favorably with the predictions of a superdislocation model presented.