SCHLACHER: Fracture toughness of textured Al2O3 grain and boundary determined by micro-cantilevers
Channel: Chair of Structural and Functional Ceramics
Date: 2022-06-03

[Title]
Fracture toughness of textured alumina grains and grain boundaries determined by micro-cantilever bending tests

[Authors]
Josef SCHLACHER
Tamás CSANÁDI
Marek VOJTKO
Roman PAPŠÍK
Ján DUSZA
Raul BERMEJO

[Event]
97th DKG Annual Meeting - Ceramics 2022
Tuesday, 8th March 2022

[Abstract]
Embedding textured alumina layers has been established as a novel design strategy to enhance the fracture resistance in ceramic laminates. It is hypothesized that the exceptional damage tolerance in these materials is mainly attributed to crack deflection events along the weaker basal grain boundaries within the textured microstructure. To prove this hypothesis, the fracture toughness of individual textured alumina grains and grain boundaries has been measured through micro-cantilever bending tests. Micro-scale notched cantilevers were milled using Focus Ion beam along the prismatic direction of the aligned textured grains and perpendicular to the elongated grain boundaries in basal orientation and tested with a nanoindentor. A shape function for notched pentagonal-shaped cantilevers was calculated using Finite element analysis to retrieve the critical stress intensity factor at the notch tip. The micro-scale fracture toughness of the textured alumina grain boundaries was found to be approximately 40% lower than the one of the grains. This experimental finding is paramount for understanding the macroscopic fracture behaviour of layered ceramics with textured microstructures and may be applied to other composite materials.