Nanoscale Anisotropic Plastic Deformation in Single Crystal Aragonite

Kearney, Cathal J.; Zhao, Z.; Bruet, B. J. F.; Radovitzky, Raúl; Boyce, Mary C.; Ortiz, Christine

doi:10.1103/physrevlett.96.255505

Cited by 61 publications

(51 citation statements)

References 25 publications

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“…The microscopic origin of this behaviour is the existence of preferential slip systems, such as the f110g,001. family [24]. The pile-up effect around the indentations was described correctly by a crystal plasticity model, which takes into account all the slip systems [24].…”

Section: Anisotropic Mechanical Properties Of Single-crystal Aragonitementioning

confidence: 99%

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Isotropic microscale mechanical properties of coral skeletons

Pasquini

Molinari

Fantazzini

et al. 2015

J. R. Soc. Interface.

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Scleractinian corals are a major source of biogenic calcium carbonate, yet the relationship between their skeletal microstructure and mechanical properties has been scarcely studied. In this work, the skeletons of two coral species: solitary Balanophyllia europaea and colonial Stylophora pistillata, were investigated by nanoindentation. The hardness H IT and Young's modulus E IT were determined from the analysis of several load -depth data on two perpendicular sections of the skeletons: longitudinal ( parallel to the main growth axis) and transverse. Within the experimental and statistical uncertainty, the average values of the mechanical parameters are independent on the section's orientation. The hydration state of the skeletons did not affect the mechanical properties. The measured values, E IT in the 76-77 GPa range, and H IT in the 4.9-5.1 GPa range, are close to the ones expected for polycrystalline pure aragonite. Notably, a small difference in H IT is observed between the species. Different from corals, single-crystal aragonite and the nacreous layer of the seashell Atrina rigida exhibit clearly orientation-dependent mechanical properties. The homogeneous and isotropic mechanical behaviour of the coral skeletons at the microscale is correlated with the microstructure, observed by electron microscopy and atomic force microscopy, and with the X-ray diffraction patterns of the longitudinal and transverse sections.

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Section: Anisotropic Mechanical Properties Of Single-crystal Aragonitementioning

confidence: 99%

“…In reference [24], the values H IT ¼ 6.2 + 0.3 GPa and H IT ¼ 4.4 + 0.4 GPa were reported for nanoindentation tests perpendicular to the planes (001) and ð 1 30Þ. The microscopic origin of this behaviour is the existence of preferential slip systems, such as the f110g,001.…”

Section: Anisotropic Mechanical Properties Of Single-crystal Aragonitementioning

confidence: 99%

Isotropic microscale mechanical properties of coral skeletons

Pasquini

Molinari

Fantazzini

et al. 2015

J. R. Soc. Interface.

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“…First, the fibre-like texture with the c axis oriented along the surface normal provides greater hardness and stiffness due to the anisotropic mechanical properties of aragonite 49 . While maintaining the out-of-plane anisotropy, the in-plane mechanical isotropy is enhanced through the large in-plane rotation of the crystallographic directions in the helical assembly.…”

Section: Articlementioning

confidence: 99%

Hierarchical structural design for fracture resistance in the shell of the pteropod Clio pyramidata

Weaver²,

Ortiz

2015

Nat Commun

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The thecosomes are a group of planktonic pteropods with thin, 1 mm-sized aragonitic shells, which are known to possess a unique helical microstructure consisting of interlocking nanofibres. Here we investigate the detailed hierarchical structural and mechanical design of the pteropod Clio pyramidata. We quantify and elucidate the macroscopic distribution of the helical structure over the entire shell (B1 mm), the structural characteristics of the helical assembly (B10-100 mm), the anisotropic cross-sectional geometry of the fibrous building blocks (B0.5-10 mm) and the heterogeneous distribution of intracrystalline organic inclusions within individual fibres (o0.5 mm). A global fibre-like crystallographic texture is observed with local in-plane rotations. Microindentation and electron microscopy studies reveal that the helical organization of the fibrous building blocks effectively constrains mechanical damages through tortuous crack propagation. Uniaxial micropillar compression and cross-sectional transmission electron microscopy directly reveal that the interlocking fibrous building blocks further retard crack propagation at the nanometre scale.

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“…It enables a realistic description of the anisotropic material flow during indentation. CP-FEM simulation of indentation has been applied to copper [46][47][48][49][50][51], minerals [52], β-titanium [53], zinc [51], and a single-crystal superalloy [54].…”

Section: Nanoindentation and Piling-up Of Materialsmentioning

confidence: 99%

Plastic anisotropy of γ-TiAl revealed by axisymmetric indentation

Zambaldi¹,

Raabe²

2010

Acta Materialia

106

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Single crystals of γ-TiAl cannot be grown in the near-stoichiometric compositions that are present inside two-phase γ/α 2 -microstructures with attractive mechanical properties. Therefore, the single crystal constitutive behavior of γ-TiAl was studied by nanoindentation experiments in single phase regions of these γ/α 2 -microstructures. The experiments were characterized by orientation microscopy and atomic force microscopy to quantify the orientation dependent mechanical response during nanoindentation. Further, they were analyzed by a 3D crystal plasticity finite element model that incorporated the deformation behavior of γ-TiAl. The spatially resolved activation of competing deformation mechanisms during indentation was used to assess their relative strengths. A convention was defined to unambiguously relate any indentation axis to a crystallographic orientation. Experiments and simulations were combined to study the orientation dependent surface pile-up. The characteristic pile-up topographies were simulated throughout the unit triangle of γ-TiAl and represented graphically in the newly introduced inverse pole figure of pile-up patterns. Through this approach, easy activation of ordinary dislocation glide in stoichiometric γ-TiAl was confirmed independently from dislocation observation by transmission electron microscopy.

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Nanoscale Anisotropic Plastic Deformation in Single Crystal Aragonite

Cited by 61 publications

References 25 publications

Isotropic microscale mechanical properties of coral skeletons

Isotropic microscale mechanical properties of coral skeletons

Hierarchical structural design for fracture resistance in the shell of the pteropod Clio pyramidata

Plastic anisotropy of γ-TiAl revealed by axisymmetric indentation

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