TY - JOUR
T1 - Biomimetic hard and tough nanoceramic Ti–Al–N film with self-assembled six-level hierarchy
AU - Meindlhumer, Michael
AU - Zalesak, Jakub
AU - Pitonak, Reinhard
AU - Todt, Juraj
AU - Sartory, Bernhard
AU - Burghammer, M.
AU - Stark, Andreas
AU - Schell, Norbert
AU - Daniel, Rostislav
AU - Keckes, Julius
AU - Lessiak, Mario
AU - Köpf, A.
AU - Weißenbacher, R.
AU - Keckes, Jozef
PY - 2019/4/28
Y1 - 2019/4/28
N2 - Nature uses self-assembly of a fairly limited selection of components to build hard and tough protective tissues like nacre and enamel. The resulting hierarchical micro/nanostructures provide decisive toughening mechanisms while preserving strength. However, to mimic microstructural and mechanical characteristics of natural materials in application-relevant synthetic nanostructures has proven to be difficult. Here, we demonstrate a biomimetic synthesis strategy, based on chemical vapour deposition technology, employed to fabricate a protective high-temperature resistant nanostructured ceramic TiAlN thin film with six levels of hierarchy. By using just two variants of gaseous precursors and through bottom-up self-assembly, an irregularly arranged hard and tough multilayer stack was formed, consisting of hard sublayers with herringbone micrograins, separated by tough interlayers with spherical nanograins, respectively composed of lamellar nanostructures of alternating coherent/incoherent, hard/tough, single-/poly-crystalline platelets. Micro- and nanomechanical testing, performed in situ in scanning and transmission electron microscopes, manifests intrinsic toughening mechanisms mediated by five types of interfaces resulting in intergranular, transgranular and cleavage fracture modes with zigzag-like crack patterns at multiple length-scales. The hierarchical 2.7 μm thick film self-assembled during ∼15 minutes of deposition time shows hardness, fracture stress and toughness of ∼31 GPa, ∼7.9 GPa and ∼4.7 MPa m
0.5 , respectively, as well as phase/microstructural thermal stability up to ∼950/900 °C. The film's microstructural and mechanical characteristics represent a milestone in the production of protective and wear-resistant thin films.
AB - Nature uses self-assembly of a fairly limited selection of components to build hard and tough protective tissues like nacre and enamel. The resulting hierarchical micro/nanostructures provide decisive toughening mechanisms while preserving strength. However, to mimic microstructural and mechanical characteristics of natural materials in application-relevant synthetic nanostructures has proven to be difficult. Here, we demonstrate a biomimetic synthesis strategy, based on chemical vapour deposition technology, employed to fabricate a protective high-temperature resistant nanostructured ceramic TiAlN thin film with six levels of hierarchy. By using just two variants of gaseous precursors and through bottom-up self-assembly, an irregularly arranged hard and tough multilayer stack was formed, consisting of hard sublayers with herringbone micrograins, separated by tough interlayers with spherical nanograins, respectively composed of lamellar nanostructures of alternating coherent/incoherent, hard/tough, single-/poly-crystalline platelets. Micro- and nanomechanical testing, performed in situ in scanning and transmission electron microscopes, manifests intrinsic toughening mechanisms mediated by five types of interfaces resulting in intergranular, transgranular and cleavage fracture modes with zigzag-like crack patterns at multiple length-scales. The hierarchical 2.7 μm thick film self-assembled during ∼15 minutes of deposition time shows hardness, fracture stress and toughness of ∼31 GPa, ∼7.9 GPa and ∼4.7 MPa m
0.5 , respectively, as well as phase/microstructural thermal stability up to ∼950/900 °C. The film's microstructural and mechanical characteristics represent a milestone in the production of protective and wear-resistant thin films.
UR - http://www.scopus.com/inward/record.url?scp=85065110268&partnerID=8YFLogxK
U2 - 10.1039/c8nr10339a
DO - 10.1039/c8nr10339a
M3 - Article
SN - 2040-3364
VL - 11.2019
SP - 7986
EP - 7995
JO - Nanoscale
JF - Nanoscale
IS - 16
ER -