Microcrack orientation in porous aluminum titanate

Microcracking of porous stabilized aluminum titanate (AT) was investigated by a combination of models and experiments. The strong hypothesis that the b-axis is completely disconnected from the surrounding material is needed in order for the integrity factor model to reproduce the macroscopic thermal expansion of AT. Electron backscattering and in situ neutron diffraction compressive tests validated this hypothesis. While the model predicts that microscopic-scale residual stresses are locked into the material after firing (compressive along the negative expansion crystal axis and tensile along the other two positive expansion axes), neutron diffraction provides evidence of this stress. Indeed, some deformation mechanisms are proposed to explain the apparent anomalous behavior of the AT under compression. Those mechanisms make combined use of experimental observations and theoretical predictions.