A practical method to determine the five-parameter orientation of intragranular boundaries in polycrystals

Lloyd, Geoffrey E.; Lee, Amicia; Kahl, Maren

doi:10.1016/j.tecto.2021.228955

Cited by 3 publications

(1 citation statement)

References 64 publications

(72 reference statements)

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“…In this study, we select intragranular boundaries that are mostly straight or only slightly curved for analyses, because straight boundaries on 2-D EBSD maps should correspond to approximately planar structures in 3-D (Lloyd et al, 1997(Lloyd et al, , 2021. Intragranular boundaries with irregular geometries in 2-D should represent a probably more sophisticated 3-D crystallographic geometry compared with planar intragranular boundaries analyzed in this study.…”

Section: Boundary Trace Analysesmentioning

confidence: 99%

Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures

et al. 2022

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During plastic deformation, strain weakening can be achieved, in part, via strain energy reduction associated with intragranular boundary development and grain boundary formation. Grain boundaries (in 2D) are segments between triple junctions, that connect to encircle grains; every boundary segment in the encircling loop has a high (>10°) misorientation angle. Intragranular boundaries terminate within grains or dissect grains, usually containing boundary segments with a low (<10°) misorientation angle. We analyze electron backscatter diffraction (EBSD) data from ice deformed at −30°C (Th≈ ${T}_{h}\approx $ 0.9). Misorientation and weighted Burgers vector (WBV) statistics are calculated along planar intragranular boundaries. Misorientation angles change markedly along each intragranular boundary, linking low‐ (<10°) and high‐angle (10–38°) segments that exhibit distinct misorientation axes and WBV directions. We suggest that these boundaries might be produced by the growth and intersection of individual intragranular boundary segments comprising dislocations with distinct slip systems. There is a fundamental difference between misorientation axis distributions of intragranular boundaries (misorientation axes mostly confined to ice basal plane) and grain boundaries (no preferred misorientation axis). These observations suggest during progressive subgrain rotation, intragranular boundaries remain crystallographically controlled up to large misorientation angles (>>10°). In contrast, the apparent lack of crystallographic control for grain boundaries suggests misorientation axes become randomized, likely due to the activation of additional mechanisms (such as grain boundary sliding) after grain boundary formation, linking boundary segments to encircle a grain. Our findings on ice intragranular boundary development and grain boundary formation may apply more broadly to other rock‐forming minerals (e.g., olivine, quartz).

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Section: Boundary Trace Analysesmentioning

confidence: 99%

Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures

et al. 2022

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Nanoscale visualization of high-angle misorientations in quartz-rich rocks using SEM-EBSD and Atomic Force Microscopy

Dey,

Chatterjee,

Ritanjali

et al. 2024

Journal of Structural Geology

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Mapping intragranular microstructures in quartz: the significance of Dauphiné twinning

Lloyd

2023

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Mapping on the microstructural scale can contribute significantly to conventional field and larger scale mapping and understanding of spatial, temporal and process-oriented relationships. Here, EBSD-based microstructural maps are presented of subgrain and Dauphine twin boundaries in undeformed sedimentary quartzite. ‘Plane Matching’ analysis permits determination of complete orientation of boundaries. A workflow is presented to facilitate necessary crystallographic calculations. Resulting maps indicate: (1) boundary plane rotation angle/axis pairs, including tilt-twist components; (2) boundary migration vectors; and (3) conventional EBSD misorientation angle/axis pairs. Subgrain boundaries are general with small misorientations and boundary plane normal directions subparallel to grain boundary stress concentrations; rotation axes are oriented sub-parallel to bedding dip (017°/10°E). Most exhibit bi-direction boundary migration vectors parallel to bedding normal. EBSD misorientation analysis results are different as they only recognise parallelism of adjacent crystal lattices. Differences are especially apparent for Dauphine twin boundaries. Maps are presented of twin boundaries using Matched Plane analysis, including explanation for lateral twin migration. Driving forces to move twin boundaries are also estimated by mapping variations in Young's Modulus between parents and twins; differences are significant, indicating Young's modulus and driving forces do not need to be large, explaining the propensity for twinning in many quartzites. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6710513

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A practical method to determine the five-parameter orientation of intragranular boundaries in polycrystals

Cited by 3 publications

References 64 publications

Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures

Using Misorientation and Weighted Burgers Vector Statistics to Understand Intragranular Boundary Development and Grain Boundary Formation at High Temperatures

Nanoscale visualization of high-angle misorientations in quartz-rich rocks using SEM-EBSD and Atomic Force Microscopy

Mapping intragranular microstructures in quartz: the significance of Dauphiné twinning

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