Interface failure in nacre-like alumina

Bioinspired ceramic-ceramic composites based on alumina platelets with a glassy interphase have recently emerged as a new class of strong and damage-resistant materials. Understanding the fracture properties of nacrelike alumina requires to know the properties of each of its components. However, only the platelets have been individually tested so far. Here we characterize at a micro scale the fracture properties of an aluminosilicate glass interphase. Micro-cantilevers prepared by FIB are tested to characterize the failure of interfaces with different angles, and thus undergoing different combined shear and tensile stress. The interface failure appears to be mainly driven by the opening stress that predominates over shear stress. It results in a local maximum opening stress of 0.72 +/- 0.18 GPa, against 3 GPa for a pack of perpendicular and aligned platelets. These results should help understand the bulk properties of nacre-like alumina composites and enable a rational design of their components and microstructures.