Cleavage Anisotropy in Tungsten Single Crystals

Riedle, Joachim; Gumbsch, Peter; Fischmeister, H. F.

doi:10.1103/physrevlett.76.3594

Cited by 135 publications

(78 citation statements)

References 15 publications

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“…91 During the orthorhombic deformation the bcc structure is simultaneously stretched along the ͓001͔ direction and compressed in the ͓110͔ direction. In the coordinate system where the x, y, and z axes are parallel to the ͓110͔, ͓110͔, and ͓001͔ directions, respectively, the deformation can be described by the following Lagrangian strain tensor for large deformations: 11 The parameter p characterizing this path is equal to 1 for the initial bcc structure and 2 at the final point corresponding again to the bcc structure with the same lattice parameters as the initial structure. Along the path the crystal has a facecentered-orthorhombic symmetry except for p = ͱ 2 that corresponds to a body-centered-tetragonal structure with the c / a ratio of 1.682.…”

Section: B Deformation Pathsmentioning

confidence: 99%

“…6,7 This transition appears to be controlled by dislocation mobility rather than by crack nucleation. [8][9][10] For example, studies of the cleavage in tungsten single crystals indicate an anisotropy with respect to both the crack plane and the direction of crack propagation, 11 suggesting that the DBT temperature and subsequent crack extension are directly related to atomic-level features of crack and dislocation propagation. In addition, the mechanical properties of tungsten are strongly dependent on alloying, impurities, and thermomechanical treatment, 12 which is a common characteristic of bcc transition metals ͑see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

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Bond-order potential for simulations of extended defects in tungsten

et al. 2007

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We present a bond-order potential (BOP) for the bcc transition metal tungsten. The bond-order potentials are a real-space semiempirical scheme for the description of interatomic interactions based on the tight-binding approximation. In the hierarchy of atomic-scale-modeling methods the BOPs thus provide a direct bridge between electronic-structure and atomistic techniques. Two variants of the BOP were constructed and extensively tested against accurate first-principles methods in order to assess the potentials' reliability and applicability. A comparison of the BOP with a central-force potential is used to demonstrate that a correct description of directional mixed covalent and metallic bonds is crucial for a successful and fully transferable model. The potentials are applied in studies of low-index surfaces, symmetrical tilt grain boundaries, and dislocations. We present a bond-order potential ͑BOP͒ for the bcc transition metal tungsten. The bond-order potentials are a real-space semiempirical scheme for the description of interatomic interactions based on the tight-binding approximation. In the hierarchy of atomic-scale-modeling methods the BOPs thus provide a direct bridge between electronic-structure and atomistic techniques. Two variants of the BOP were constructed and extensively tested against accurate first-principles methods in order to assess the potentials' reliability and applicability. A comparison of the BOP with a central-force potential is used to demonstrate that a correct description of directional mixed covalent and metallic bonds is crucial for a successful and fully transferable model. The potentials are applied in studies of low-index surfaces, symmetrical tilt grain boundaries, and dislocations.

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Section: B Deformation Pathsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bond-order potential for simulations of extended defects in tungsten

et al. 2007

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“…While most theoretical and computational studies have focused on elastic anisotropy [1][2][3], the anisotropy of the fracture toughness influences more strongly the crack propagation of a wide variety of materials including single crystals [4][5][6], extruded polymers [7], geological materials [8,9], including sedimentary [10] and granitic rocks [11], or apple flesh [12]. The issue of brittle crack propagation in materials with anisotropic surface energy deeply interrogates our understanding of fracture and is receiving increasing attention from a variety of points of view, such as molecular dynamics [13], continuum mechanics [14,15], phase-field modeling [16,17], and experiments [7,18].…”

Section: Introductionmentioning

confidence: 99%

Phase‐field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy

Peco

Millán

et al. 2014

Numerical Meth Engineering

162

102

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SUMMARYCrack propagation in brittle materials with anisotropic surface energy is important in applications involving single crystals, extruded polymers, or geological and organic materials. Furthermore, when this anisotropy is strong, the phenomenology of crack propagation becomes very rich, with forbidden crack propagation directions or complex sawtooth crack patterns. This problem interrogates fundamental issues in fracture mechanics, including the principles behind the selection of crack direction. Here, we propose a variational phase-field model for strongly anisotropic fracture, which resorts to the extended Cahn-Hilliard framework proposed in the context of crystal growth. Previous phase-field models for anisotropic fracture were formulated in a framework only allowing for weak anisotropy. We implement numerically our higher-order phase-field model with smooth local maximum entropy approximants in a direct Galerkin method. The numerical results exhibit all the features of strongly anisotropic fracture and reproduce strikingly well recent experimental observations.

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“…Also, within the same WC can appear so-called river patterns (marked as dotted arrows in Fig. 4) [40,41]. On the other hand, the presence of dimples associated with ductile fracture is lower.…”

Section: Accepted Manuscript 12mentioning

confidence: 99%

Influence of temperature on the biaxial strength of cemented carbides with different microstructures

Chicardi

Bermejo

Gotor

et al. 2018

International Journal of Refractory Metals and Hard Materials

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Abstract. The effect of the temperature on the mechanical strength of WC-Co cemented carbides with different microstructures (grain size and binder content) was evaluated. Biaxial flexural tests were performed on three cemented carbide grades at 600°C using the ball-on-three-balls (B3B) method. Results were interpreted by Weibull statistics and compared to biaxial strength results at room temperature. A detailed fractographic analysis, supported by Linear Elastic Fracture Mechanics, was performed to differentiate the nature and size of critical defects and the mechanism responsible for the fracture. A significant decrease in the mechanical strength (around 30%) was observed at 600ºC for all grades of cemented carbides. This fact was ascribed to the change in the critical flaw population from sub-surface (at room temperature) to surface defects, associated with the selective oxidation of Co. Additionally, an estimation of the fracture toughness at 600°C was attempted for the three cemented carbides, based upon the B3B strength results, the corresponding number of the tested specimens fragments and the macroscopic area of the B3B fracture surfaces. The fracture toughness was not ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T2 affected by the temperature, at least up to 600ºC. In addition, the good agreement with the Single Edge Notch Beam toughness data suggests the possibility of employing this approach for fracture toughness evaluation of brittle materials under different testing conditions.

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Cleavage Anisotropy in Tungsten Single Crystals

Cited by 135 publications

References 15 publications

Bond-order potential for simulations of extended defects in tungsten

Bond-order potential for simulations of extended defects in tungsten

Phase‐field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy

Influence of temperature on the biaxial strength of cemented carbides with different microstructures

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