A finite element method to calculate geometrically necessary dislocation density: Accounting for orientation discontinuities in polycrystals

Demir, Eralp; Horton, Edward William; Kareer, Anna; Collins, David M.; Mostafavi, Mahmoud; Knowles, David

doi:10.1016/j.actamat.2022.118658

Cited by 9 publications

(3 citation statements)

References 55 publications

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“…The dislocation density (δ) was calculated using the formula 56 , 57 : where δ represents the dislocation density and D is the crystallite size.…”

Section: Methodsmentioning

confidence: 99%

Investigating the impact of electron beam irradiation on electrical, magnetic, and optical properties of XLPE/Co3O4 nanocomposites

Ghobashy,

Sharshir,

Zaghlool

et al. 2024

Sci Rep

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Nowadays, many researchers aim to fill polymer materials with inorganic nanoparticles to enhance the polymer properties and gain the merits of the polymeric host matrix. Sol–gel synthesized Co3O4 nanoparticles are subjected to different doses of electron beam (10, 20, and 30 kGy) to study their physiochemical properties and choose the optimized nanoparticles to fill our polymeric matrix. Crosslinked polyethylene (XLPE) has been filled with 5 wt % of un-irradiated cobalt oxide nanoparticles using the melt extruder method. The structural, optical, magnetic, and electrical properties of the XLPE/Co3O4 nanocomposite before and after exposure to different doses of electron beam radiation have been characterized. The crystallite size of face-centered cubic spinel Co3O4 nanoparticles has been confirmed by XRD whereas and their unique truncated octahedral shape obviously appears in SEM micrographs. The crystallite size of Co3O4 nanoparticles has decreased from 47.5 to 31.5 nm upon irradiation at a dose of 30 kGy, and significantly decreased to 18.5 nm upon filling inside XLPE matrix. Related to the oxidation effect of the electron beam, the Co2+/Co3+ ratio on the surface of Co3O4 nanoparticles has decreased upon irradiation as verified by XPS technique. This consequently caused the partial elimination of oxygen vacancies, mainly responsible for the weak ferromagnetic behavior of Co3O4 in its nanoscale. This appears as decreased saturation magnetization as depicted by VSM. The XLPE/Co3O4 nanocomposite has also shown weak ferromagnetic behavior but the coercive field (Hc) has increased from 112.57 to 175.72 G upon filling inside XLPE matrix and decreased to 135.18 G after irradiating the nanocomposite at a dose of 30 kGy. The ionic conductivity of XLPE has increased from 0.133 × 10–7 to 2.198 × 10–3 S/cm upon filling with Co3O4 nanoparticles while a slight increase is observed upon irradiation.

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“…The dislocation density (δ) was calculated using the formula 56 , 57 : where δ represents the dislocation density and D is the crystallite size.…”

Section: Methodsmentioning

confidence: 99%

Investigating the impact of electron beam irradiation on electrical, magnetic, and optical properties of XLPE/Co3O4 nanocomposites

Ghobashy,

Sharshir,

Zaghlool

et al. 2024

Sci Rep

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“…The improvement could be nearly 20-fold for high-quality EBSPs and down to 14% for fast acquisitions. FPM's more accurate crystal orientations would contribute to orientation-based characterization techniques, such as the GND density evaluation on each slip system [10]. 2.…”

Section: Acquisitions With Different Rotation Angles βmentioning

confidence: 99%

“…Though demanding in computing capacity, DI has proven very robust in the presence of high noise level [7] and able to distinguish phases of the same Bravais lattice and different lattice constants [8]. Several post-processing algorithms have been proposed to reduce the orientation indexation noise, such as the linear adaptation of smoothing splines filter [9], or a finite element framework to reduce orientation discontinuity [10]. Those filters result in lower estimations of geometrically necessary dislocation (GND) densities and a poorer spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Accuracy assessment of crystal orientation indexations by EBSD

Shi,

Loisnard,

et al. 2024

Meas. Sci. Technol.

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Accuracy and uncertainty analyses are essential for every measurement technology. In crystal orientation indexation by electron backscatter diffraction (EBSD), a series of accuracy estimations have been made for the Hough transform and dictionary indexation methods. The mean angular deviation is a standard parameter to indicate orientation accuracy, but this criterion is indirect and closely related to the accuracy of the projection center coordinates. Precise known orientation relationships are necessary to evaluate orientation accuracy without the ground truth. The current work uses the natural crystal twins and hardware orientation relationships to assess the orientation accuracy directly. The accuracy level for different EBSD analysis methods is compared through four experimental data sets of varying pattern definitions and noise levels. It is found that the full pattern match (FPM) algorithms improve the accuracy as compared to Hough indexation, and the gain varies greatly between 14% for fast acquisitions and 20 times for high-quality patterns. Depending on the resolution and quality of diffraction patterns, FPM results in an accuracy of crystal orientation between 0.04° and 0.9°. Comparing the two FPM variants, matching the gradients of diffraction patterns performs better in the case of high-to-median quality acquisitions while matching the pattern itself is more accurate for more noisy and low-definition patterns.

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Effect of grain boundary misorientation and carbide precipitation on damage initiation: A coupled crystal plasticity and phase field damage study

Salvini,

Grilli,

Demir

et al. 2024

International Journal of Plasticity

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A finite element method to calculate geometrically necessary dislocation density: Accounting for orientation discontinuities in polycrystals

Cited by 9 publications

References 55 publications

Investigating the impact of electron beam irradiation on electrical, magnetic, and optical properties of XLPE/Co3O4 nanocomposites

Investigating the impact of electron beam irradiation on electrical, magnetic, and optical properties of XLPE/Co3O4 nanocomposites

Accuracy assessment of crystal orientation indexations by EBSD

Effect of grain boundary misorientation and carbide precipitation on damage initiation: A coupled crystal plasticity and phase field damage study

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