In this work, we have shown that all samples show crack deviation in SENB tests, whether they have a glass phase or not (FIGURE ). Crack propagation is therefore controlled by the interfaces between the alumina platelets, whether the interface contains or not a glass phase (FIGURE ). When studying the R-curves of the different samples (FIGURE ), at first glance the slope of the curves, i.e. the evolution of their toughness with the depth of the crack, differs according to the sample. This is potentially an effect of the difference in composition and therefore of the presence of glass or zirconia at the interfaces between the platelets.