Effect of reference point selection on microscopic stress measurement using EBSD

Mikami, Yoshiki; Oda, Kin-ya; Kamaya, Masayuki; Mochizuki, Masahito

doi:10.1016/j.msea.2015.09.004

Cited by 41 publications

(24 citation statements)

References 50 publications

(66 reference statements)

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“…Nonetheless, the results document the magnitude of heterogeneity in both elastic strain and residual stress. We follow the approach of Jiang et al () and Mikami et al () by subtracting the mean of each component of the stress heterogeneities from the measured stress state at each point (i.e., normalizing the mean of each stress component to zero). This recasts the results as stress heterogeneities relative to the mean stress state in each map.…”

Section: Methodsmentioning

confidence: 99%

Dislocation Interactions in Olivine Revealed by HR‐EBSD

et al. 2017

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Interactions between dislocations potentially provide a control on strain rates produced by dislocation motion during creep of rocks at high temperatures. However, it has been difficult to establish the dominant types of interactions and their influence on the rheological properties of creeping rocks due to a lack of suitable observational techniques. We apply high‐angular resolution electron backscatter diffraction to map geometrically necessary dislocation (GND) density, elastic strain, and residual stress in experimentally deformed single crystals of olivine. Short‐range interactions are revealed by cross correlation of GND density maps. Spatial correlations between dislocation types indicate that noncollinear interactions may impede motion of proximal dislocations at temperatures of 1000°C and 1200°C. Long‐range interactions are revealed by autocorrelation of GND density maps. These analyses reveal periodic variations in GND density and sign, with characteristic length scales on the order of 1–10 μm. These structures are spatially associated with variations in elastic strain and residual stress on the order of 10−3 and 100 MPa, respectively. Therefore, short‐range interactions generate local accumulations of dislocations, leading to heterogeneous internal stress fields that influence dislocation motion over longer length scales. The impacts of these short‐ and/or long‐range interactions on dislocation velocities may therefore influence the strain rate of the bulk material and are an important consideration for future models of dislocation‐mediated deformation mechanisms in olivine. Establishing the types and impacts of dislocation interactions that occur across a range of laboratory and natural deformation conditions will help to establish the reliability of extrapolating laboratory‐derived flow laws to real Earth conditions.

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Section: Methodsmentioning

confidence: 99%

Dislocation Interactions in Olivine Revealed by HR‐EBSD

et al. 2017

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“…The grain size data were estimated using a grain tolerance angle of 5° and the minimum grain size was chosen as 2 pixels. All datum points with a confidence index (CI that quantifies the reliability of the indexed pattern) lower than 0.05 were excluded from the measurements [27].…”

Section: Methodsmentioning

confidence: 99%

Microstructural peculiarities and textural characteristics of Ni–W sheet alloy after accumulative roll-bonding and annealing

et al. 2020

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In the present study, the through thickness morphological and textural characteristics of a Ni-14W sheet, processed by accumulative roll-bonding (ARB) up to 4 cycles (ε = 3.2) and annealed at 1100 °C for 1 h, were investigated using electron backscatter diffraction. In the internal layers, the microstructure exhibited a small grains size free of twins and contained high fraction of low angle grain boundaries due the domination of {001}〈100〉 Cube orientation. At the surface layers, grains were coarser and contained high fraction of twins, while texture was characterized by retained shear components. The results showed that the heterogeneity of annealed microstructure texture decreased with the increasing number of ARB processing. Particle stimulated nucleation mechanism was evidenced at the vicinity of some bonding interfaces due to the presence of metallic inclusions resulting from wire-brushing procedure. As a result, the orientation of the new recrystallized grains was rather random and the grain size was stabilized by a pining effect which contributed to the microstructure heterogeneity. A successful bonding was achieved with increasing number of ARB cycles as shown by the transformation of interfaces into grain boundaries and their subsequent migration.

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“…In deformed geological materials the strain state at the reference point is typically unknown, and it is likely that there are few or no areas that are free from elastic strain. However, strains and stresses can be readily recalculated relative to the mean strain and stress state within each grain area, which is a more intuitive form to interpret and is independent of the choice of reference point (Jiang et al, 2013b;Mikami et al, 2015;. Similarly, GND density estimates are independent of the choice of reference point as they are calculated from the spatial gradients of the rotation fields.…”

Section: 1029/2019jb017867mentioning

confidence: 99%

“…Figure 6d demonstrates that the intragranular stress heterogeneities calculated from the strains after pattern remapping and the second pass of cross correlation generally still have magnitudes on the order of 1 GPa. In Figure 6e, these stresses have been recalculated by subtracting the mean value within each grain area to remove the effect of the choice of reference points (Jiang et al, 2013b;Mikami et al, 2015;. The result gives the intragranular stress heterogeneities relative to the (unknown) mean stress state within each grain area.…”

Section: 1029/2019jb017867mentioning

confidence: 99%

High-angular resolution electron backscatter diffraction as a new tool for mapping lattice distortion in geological minerals

Wallis¹,

Hansen²,

Britton³

et al. 2019

Preprint

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Analysis of distortions of the crystal lattice within individual mineral grains is central to the investigation of microscale processes that control and record tectonic events. These distortions are generally combinations of lattice rotations and elastic strains, but a lack of suitable observational techniques has prevented these components being mapped simultaneously and routinely in earth science laboratories. However, the technique of high-angular resolution electron backscatter diffraction (HR-EBSD) provides the opportunity to simultaneously map lattice rotations and elastic strains with exceptional precision, on the order of 0.01° for rotations and 10^-4 in strain, using a scanning electron microscope. Importantly, these rotations and lattice strains relate to densities of geometrically necessary dislocations and residual stresses. Recent works have begun to apply and adapt HR-EBSD to geological minerals, highlighting the potential of the technique to provide new insights into the microphysics of rock deformation. Therefore, the purpose of this overview is to provide a summary of the technique, to identify caveats and targets for further development, and to suggest areas where it offers potential for major advances. In particular, HR-EBSD is well suited to characterising the roles of different dislocation types during crystal plastic deformation and to mapping heterogeneous internal stress fields associated with specific deformation mechanisms/microstructures or changes in temperature, confining pressure, or applied deviatoric stress. These capabilities make HR-EBSD a particularly powerful new technique for analysing the microstructures of deformed geological materials.

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Effect of reference point selection on microscopic stress measurement using EBSD

Cited by 41 publications

References 50 publications

Dislocation Interactions in Olivine Revealed by HR‐EBSD

Dislocation Interactions in Olivine Revealed by HR‐EBSD

Microstructural peculiarities and textural characteristics of Ni–W sheet alloy after accumulative roll-bonding and annealing

High-angular resolution electron backscatter diffraction as a new tool for mapping lattice distortion in geological minerals

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