Residual stress in ceramics with large thermal expansion anisotropy

Residual stress was measured in sintered and heat-treated Fe_2TiO_5 samples with various grain sizes. The influence of texturing was assessed by comparing the residual stress states of samples having randomly oriented grains and highly oriented grains produced through magnetically assisted processing. The residual stress was measured with x-ray diffraction using Cr K_α radiation. Due to the significant texture and the consequential oscillations in the d_(φψ) vs sin^2 ψ data, the residual stress was calculated using the Marion-Cohen method. Textured samples showed significantly lower residual stresses except when spontaneous microcracking accompanied grain growth in the randomly oriented systems. Elastic modulus measurements showed a direct correlation between the decrease in residual stress and the microcrack density