Anisotropic brittle-ductile transition of monocrystalline sapphire during orthogonal cutting and nanoindentation experiments

Maas, Philipp; Mizumoto, Yuta; Kakinuma, Yasuhiro; Min, Sangkee

doi:10.1016/j.npe.2018.09.005

Cited by 19 publications

(5 citation statements)

References 33 publications

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“…Figure 6 shows the relationship between scratch direction and (a) scratch force and (b) groove depth, respectively. Publications [ 23 , 24 , 25 ] also reported that the critical depth of cut for sapphire in the ductile-regime was less than 0.24 µm while nanoscratched depths were lower than 85 nm in this study. Therefore, the ductile-regime removal and deformation mechanisms should be discussed in this study, because all the nanoscratch experiments were completed within the ductile-regime.…”

Section: Resultssupporting

confidence: 64%

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

et al. 2021

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In this study, single groove nanoscratch experiments using a friction force microscope (FFM) with a monocrystalline diamond tip were conducted on a c-plane sapphire wafer to analyze the ductile-regime removal and deformation mechanism including the anisotropy. Various characteristics, such as scratch force, depth, and specific energy for each representative scratch direction on the c-plane of sapphire, were manifested by the FFM, and the results of the specific scratch energy showed a trend of six-fold symmetry on taking lower values than those of the other scratch directions when the scratch directions correspond to the basal slip directions as 0001⟨112¯0⟩. Since this can be due to the effect of most probably basal slip or less probably basal twinning on the c-plane, a molecular dynamics (MD) simulation of zinc, which is one of the hexagonal close-packed (hcp) crystals with similar slip/twining systems, was attempted to clarify the phenomena. The comparison results between the nanoscratch experiment and the MD simulation revealed that both the specific scratch energy and the burr height were minimized when scratched in the direction of the basal slip. Therefore, it was found that both the machining efficiency and the accuracy could be improved by scratching in the direction of the basal slip in the single groove nanoscratch of c-plane sapphire.

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Section: Resultssupporting

confidence: 64%

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

et al. 2021

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“…Figure (a2) and (b1) depicts the angles between lateral cracks and the ductile flow lines as approximately 20° for [−1–12] and 60° for [−110]. These cracks, forming on the groove’s outer surface due to shear stress release, differ from those within the groove surface. − The presence of cracks and chips, correlating with the COF, indicates that single ductile deformation no longer solely characterizes the surface deformation under increased normal load conditions on the monocrystalline BaF 2 (111) crystal plane. Instead, it encompasses the combined effects of brittle fracture and crystal debris.…”

Section: Resultsmentioning

confidence: 99%

Anisotropy Dependence of Material Deformation Mechanisms in Nanoscratching Monocrystalline BaF₂: Experiments and Atomic Simulations

Du,

Yang,

Deng

et al. 2024

ACS Appl. Mater. Interfaces

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Monocrystalline barium fluoride (BaF 2 ), known for its exceptional optical properties in the infrared spectrum, exhibits anisotropy that influences surface quality and material removal efficiency during ultraprecision machining. This research explores the impact of anisotropy on the deformation and removal mechanisms of monocrystalline BaF 2 by integrating nanoscratch tests with molecular dynamics (MD) simulations. Nanoscratch tests conducted on variously oriented monocrystalline BaF 2 surfaces using a ramp loading mode facilitated the identification of surface cracks and a systematic description of material removal behaviors. This study elucidates the effect of crystal orientation on the ductile−brittle transition (DBT) of monocrystalline BaF 2 , further developing a critical depth prediction model for DBT on the (111) crystal plane to reveal the underlying anisotropy mechanisms. Moreover, nanofriction and wear behaviors in monocrystalline BaF 2 are found to be predominantly influenced by scratch direction, crystal surface, and applied load, with the ( 110) and ( 100) planes showing pronounced frictional and wear anisotropy. A coefficient of friction model, accounting for the material's elastic recovery, establishes the intrinsic relationship between anisotropic friction and wear behaviors, the size effect, and scratch direction. Lastly, MD modeling of nanoscratched monocrystalline BaF 2 reveals the diversity of dislocations and strain distributions along the (111) [−110] and [−1−12] crystal directions, offering atomic scale insights into the origins of BaF 2 anisotropy. Thus, this study provides a theoretical foundation for the efficient processing of fluorine-based infrared optic materials exhibiting anisotropy.

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“…It is considered that there is a cohesive zone at the grain boundary. [1,24,30] In the dynamic damage evolution process of SCS, the action of external force overcomes the fracture energy of grain boundary surface, [1,5,6,8,18,23,24,30] causing the formation and propagation of interface crack.…”

Section: Parallel To C-axismentioning

confidence: 99%

“…The normal fracture energy of the interface is Φ n = 40 J m -2 , and the tangential fracture energy is Φ t = 6 J m -2 . [23,24,29,30,37]…”

Section: Modeling Of Cohesive Elementmentioning

confidence: 99%

Investigation on Dynamic Impact Mechanism of Single Crystal Sapphire 3D Model Based on Cohesive Zone Law

Wang

2023

Cryst. Res. Technol.

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Based on mesh reconstruction technology, a 3D solid model of single crystal sapphire (SCS) with global embedded cohesive element is established in this study. Using exponential cohesive zone law (CZL), the anisotropy of SCS can be effectively characterized by assigning the mechanical properties of matrix element and cohesive element. Taking the C‐plane SCS model as the research object, the whole process of dynamic evolution of cracks in the model under high‐speed surface impact and high concentrated stress impact is reproduced by finite element simulation technology. The simulation is compared with the experimental results from the aspects of crack initiation morphology, crack propagation path, sample fragmentation form, and mechanical response curve. The dynamic compressive strength reaches 1630.3 MPa with the impact velocity of 30 m s–1 in surface impact type. The initial maximum loading force reaches 320 N when the impact velocity is 8.35 m s–1 in the indentation impact type. In addition, by combining the simulation results, this study clarifies the mechanism of strain rate effect exhibited by SCS from the perspective of stress–strain data and crack evolution characteristics. Therefore, the model established in this study can effectively reflect the mechanical behavior of SCS under impact load.

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Anisotropic brittle-ductile transition of monocrystalline sapphire during orthogonal cutting and nanoindentation experiments

Cited by 19 publications

References 33 publications

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

Anisotropy Dependence of Material Deformation Mechanisms in Nanoscratching Monocrystalline BaF₂: Experiments and Atomic Simulations

Investigation on Dynamic Impact Mechanism of Single Crystal Sapphire 3D Model Based on Cohesive Zone Law

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Anisotropic brittle-ductile transition of monocrystalline sapphire during orthogonal cutting and nanoindentation experiments

Cited by 19 publications

References 33 publications

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

Analysis of Nanoscratch Mechanism of C-Plane Sapphire with the Aid of Molecular Dynamics Simulation of Hcp Crystal

Anisotropy Dependence of Material Deformation Mechanisms in Nanoscratching Monocrystalline BaF2: Experiments and Atomic Simulations

Investigation on Dynamic Impact Mechanism of Single Crystal Sapphire 3D Model Based on Cohesive Zone Law

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Anisotropy Dependence of Material Deformation Mechanisms in Nanoscratching Monocrystalline BaF₂: Experiments and Atomic Simulations