Observations of Intergranular Stress Corrosion Cracking in a Grain-Mapped Polycrystal

King, Andrew; Johnson, Gregory R.; Engelberg, Dirk; Ludwig, Wolfgang; Marrow, James

doi:10.1126/science.1156211

Cited by 441 publications

(264 citation statements)

References 20 publications

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“…Various experimental techniques are available for microstructural characterization [25,26,27,28,29,71,72,73] and their output is sometimes used as input for finite element (FE) analysis [74,75,48,49]. However a complete 3D reconstruction still remains a challenging task.…”

Section: Artificial Microstructure Generationmentioning

confidence: 99%

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

Benedetti

Aliabadi

2013

Computer Methods in Applied Mechanics and Engineering

117

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In this study, a novel three-dimensional micro-mechanical crystal-level model for the analysis of intergranular degradation and failure in polycrystalline materials is presented. The polycrystalline microstructures are generated as Voronoi tessellations, that are able to retain the main statistical features of polycrystalline aggregates. The formulation is based on a grain-boundary integral representation of the elastic problem for the aggregate crystals, that are modeled as threedimensional anisotropic elastic domains with random orientation in the three-dimensional space. The boundary integral representation involves only intergranular variables, namely interface displacement discontinuities and interface tractions, that play an important role in the micromechanics of polycrystals. The integrity of the aggregate is restored by enforcing suitable interface conditions, at the interface between adjacent grains. The onset and evolution of damage at the grain boundaries is modeled using an extrinsic non-potential irreversible cohesive linear law, able to address mixed-mode failure conditions. The derivation of the traction-separation law and its relation with potential-based laws is discussed. Upon interface failure, a non-linear frictional contact analysis is used, to address separation, sliding or sticking between micro-crack surfaces. To avoid a sudden transition between cohesive and contact laws, when interface failure happens under compressive loading conditions, the concept of cohesive-frictional law is introduced, to model the smooth onset of friction during the mode II decohesion process. The incrementaliterative algorithm for tracking the degradation and micro-cracking evolution is presented and discussed. Several numerical tests on pseudo-and fully three-dimensional polycrystalline microstructures have been performed. The influence of several intergranular parameters, such as cohesive strength, fracture toughness and friction, on the microcracking patterns and on the aggregate response of the polycrystals has been analyzed. The tests have demonstrated the capability of the formulation to track the nucleation, evolution and coalescence of multiple damage and cracks, under either tensile or compressive loads.

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Section: Artificial Microstructure Generationmentioning

confidence: 99%

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

Benedetti

Aliabadi

2013

Computer Methods in Applied Mechanics and Engineering

117

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“…QC models of 2D tilt GBs were created by projection of the 3D crystallography orientations along the <110> or <100> directions. Special boundaries were represented by coincident site lattice (CSL) GBs with low Σ values corresponding to the reciprocal density of coincident atoms [37,38]. We considered a Σ9(221) GB, which has previously been predicted to simulate GB sliding by atomic shuffling [30], and a Σ27(115) prone to shear-coupled GB migration with a <110> tilt axis, as well as a Σ5(210) GB (also prone to migration) with a <100> tilt axis.…”

Section: Computational Methodologymentioning

confidence: 99%

Quasicontinuum study of the shear behavior of defective tilt grain boundaries in Cu

2014

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Atomistic simulations using the quasicontinuum method are used to study the role of vacancy defects and angström-scale voids on the mechanical behavior of five tilt bicrystals containing grain boundaries (GBs) that have been predicted to exhibit characteristic deformation processes of nanocrystalline and nanotwinned metals : GB-mediated dislocation emission, interface sliding, and shear-coupled GB migration. We demonstrate that such nanoscale defects have a profound impact on interfacial shear strength and underlying deformation mechanisms in copper GBs due to void-induced local stresses. In asymmetric high and low angle GBs, we find that voids become preferential sites for dislocation nucleation when the void size exceeds 4 Å. In symmetric Σ9(221) GBs prone to sliding, voids are shown to shield the local shear stress, which considerably reduces the extent of atom shuffling at the interface. In symmetric Σ5(210) and Σ27(115) GBs, we find that the effect of voids on shear-coupled GB migration depends on the GB tilt direction considered, as well as on the size and number of voids. Remarkably, large voids can completely abate the GB migration process in Σ27(115) GBs. For all GB types, the interfacial shear strength is shown to decrease linearly as the volume fraction of voids at the interface increases ; however, this study also suggests that this decrease is much more pronounced in GBs deforming by sliding than by dislocation nucleation or migration, owing to larger void-induced stresses.

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“…In the variant called Diffraction Contrast Tomography (DCT) only one near field-detector is used [15][16][17]. DCT has been shown to be a powerful tool for studies of short cracks, as space-filling 3D maps of grains and grain orientations can be provided and directly compared to 3D movies of the crack front as it penetrates through the sample [18,19].…”

Section: Introductionmentioning

confidence: 99%

Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

et al. 2012

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Observations of Intergranular Stress Corrosion Cracking in a Grain-Mapped Polycrystal

Cited by 441 publications

References 20 publications

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials

Quasicontinuum study of the shear behavior of defective tilt grain boundaries in Cu

Measuring the stress field around an evolving crack in tensile deformed Mg AZ31 using three-dimensional X-ray diffraction

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