TY - JOUR

T1 - Anisotropy of fracture toughness in nanostructured ceramics controlled by grain boundary design

AU - Daniel, Rostislav

AU - Meindlhumer, Michael

AU - Baumegger, Walter

AU - Todt, Juraj

AU - Zalesak, Jakub

AU - Ziegelwanger, Tobias

AU - Mitterer, Christian

AU - Keckes, Jozef

PY - 2019

Y1 - 2019

N2 - The fracture toughness of nanostructured materials depends on anisotropic physical properties of individual microstructural features, their texture and/or topology. In this work, intentionally sculptured grain boundaries of low cohesive energy were used to form “weak” and “tough” crack propagation directions within a nanocrystalline TiN film, allowing to correlate the directional arrangement of grains and anisotropy of fracture toughness. By using a selective micromechanical testing approach, two different cracking directions were probed in a scanning electron microscope by loading microcantilever beam specimens prepared parallel and perpendicular to the stacked direction of the alternately tilted columnar grains. The fracture toughness along the sculptured grain boundaries was ~30% higher due to effective multiple crack deflection at the kink planes, which was not observed along weak cleavage planes in the stacked direction. The results indicate the fundamental importance of microstructural design in the synthesis of tough nanostructured ceramics, whose anisotropic mechanical properties can be controlled effectively by incorporating dedicated microstructural features of well-defined topology, orientation and density.

AB - The fracture toughness of nanostructured materials depends on anisotropic physical properties of individual microstructural features, their texture and/or topology. In this work, intentionally sculptured grain boundaries of low cohesive energy were used to form “weak” and “tough” crack propagation directions within a nanocrystalline TiN film, allowing to correlate the directional arrangement of grains and anisotropy of fracture toughness. By using a selective micromechanical testing approach, two different cracking directions were probed in a scanning electron microscope by loading microcantilever beam specimens prepared parallel and perpendicular to the stacked direction of the alternately tilted columnar grains. The fracture toughness along the sculptured grain boundaries was ~30% higher due to effective multiple crack deflection at the kink planes, which was not observed along weak cleavage planes in the stacked direction. The results indicate the fundamental importance of microstructural design in the synthesis of tough nanostructured ceramics, whose anisotropic mechanical properties can be controlled effectively by incorporating dedicated microstructural features of well-defined topology, orientation and density.

UR - http://www.scopus.com/inward/record.url?scp=85056657651&partnerID=8YFLogxK

U2 - 10.1016/j.matdes.2018.11.028

DO - 10.1016/j.matdes.2018.11.028

M3 - Article

VL - 161.2019

SP - 80

EP - 85

JO - Materials and Design

JF - Materials and Design

SN - 0264-1275

IS - January

ER -