To quantify the quality of the interface between platelets for different composition, it would be necessary to be able to carry out crack tests only in opening mode I, either by making large samples (to open the interfaces in bending or using wedge testing) or by carrying out micromechanical tests . Indeed, the capability of nacrelike alumina to deflect the cracks initiated from a notch is beneficial to its crack propagation resistance, it does not prevent brittle fracture on specimens without notches, these samples showing a linear elastic behaviour up to failure.