G. Pezzotti et al., Strengthening contribution arising from residual stresses in Al2O3/ZrO2 composites: a piezo-spectroscopy investigation, J EUR CERAM, 19(2), 1999, pp. 247-253
Piezo-spectroscopy measurements have been performed in order to obtain info
rmation about the internal stresses in a series of (2 mol% Y2O3-stabilized)
ZrO2 ceramics added with fine Al2O3 dispersoids. These composites were pre
viously reported to fracture at remarkably high strength levels. Residual s
tresses arising from the thermal mismatch between the ZrO2 matrix and the A
l2O3 dispersoids were found to be of the order of several hundreds MPa, in
agreement with the predictions of an elastic stochastic stress analysis. Ta
king into consideration the results of the present piezo-spectroscopic anal
ysis, a micromechanism of microcrack shielding by residual microstresses ha
s been proposed, which overlaps with the effect of phase transformation on
strength. A theoretical assessment is given which enables one to explain th
e presence of a maximum of strength at 0.2-0.4 volume fraction of Al2O3 dis
persoid. (C) 1998 Elsevier Science Limited. All rights reserved.