Grain Size, Size‐Distribution and Dislocation Structure from Diffraction Peak Profile Analysis

Ungár, Tamás; Gubicza, Jenő

doi:10.1002/9781118804537.ch67

Cited by 3 publications

(3 citation statements)

References 37 publications

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“…The analysis of the line broadening was carried out using the Origin-6G computer program. Crystalline domains sizes D, values of crystalline lattice distortion and dislocation density ρ were estimated by means of Williamson-Hall methods [18,19]. The texture analysis was performed using the method of inverse pole figures (IPF) on the measurements in the normal direction (ND) to the rolling plane (ND IPF) and the rolling direction (RD IPF) taken on a DRON-3M diffractometer by using of the MoKα radiation in reflection mode from two sides of sheets after the corresponding number cycles of AB.…”

Section: Eejp 1 (2020)mentioning

confidence: 99%

“…2, 4) was found. Therefore, further analysis was performed using the modified Williamson -Hall method [19]. The method for processing the width of diffraction peaks makes it possible to estimate the dislocations density.…”

Section: Eejp 1 (2020)mentioning

confidence: 99%

“…The method for processing the width of diffraction peaks makes it possible to estimate the dislocations density. Assuming that the strain broadening of the lines is due to dislocations and that the average dislocation contrast factor С is known, the full width at half maximum (FWHM) of the X-ray diffraction peak (XRD) with allowance for instrumental correction and correction for absorption can be represented using a modified equation Williamson -Hall as follows [19]:…”

Section: Eejp 1 (2020)mentioning

confidence: 99%

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Effect of Kind of Deformation on Young's Modulus, Damage Parameter, Texture and Structure of Alloy Mg – 5% Li (wt)

Usov

Brokmeier²,

Shkatulyak

et al. 2020

EEJP

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Effect of deformation by extrusion, rolling after extrusion (in combination with annealing and changing the rolling direction), and subsequent alternating bending (AB) with the number of cycles 0.5, 1, 3, and 5 on the elastic modulus (E), damage accumulation parameter (damage parameter ω), crystallographic texture, and substructure parameters of the binary Mg-5%Li alloy have been studied. The damage parameter (0 ≤ ω ≤ 1), which is interpreted as the relative reduction in the effective load-bearing cross-sectional area due to damage accumulation, was found by the change in the elastic modulus after various above types of deformation. At this, we used to compare equivalent deformation and equivalent elastic energy models. The substructure parameters (crystalline domains sizes D, lattice distortion ε, dislocation density ρ) were estimated by analyzing the physical broadening of the lines diffraction on the crystal lattice of studied alloy of the penetrating hard X-ray synchrotron radiation. It was found that in the studied alloy, sheet forms a texture, at which the hexagonal prism axis is 90° deviated from the normal direction (ND) to the sheet up to transverse direction (TD) after extrusion of the ingot at 350°C in combination with its further rolling in the direction of extrusion axis (rolling direction RD) to a thickness of 4.5 mm and annealing at 350°C after each pass. At this the crystallographic directions and coincide with RD. The texture, at which the hexagonal prism axis is deviated from ND to TD by angles ranging from 15 to 70° (unlike from texture of basal type of the pure magnesium) is formed after further rolling of studied alloy to a thickness of 1 mm with the changing of the RD on 90° in combination with annealing at 350°C after each pass. The crystallographic direction coincides with RD. The anisotropy of above mentioned characteristics was found. Correlation and regression analysis showed that the anisotropy and the values of E, D, ε, and ρ, are decreased, and the values of ω are increased with an increase of alternating bend cycles’ number. It is shown that changes in the above characteristics are mainly due to the crystallographic texture formed during thermomechanical processing and subsequent alternating bending of Mg-5%Li alloy sheets, which is confirmed by data of correlation and regression analysis.

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Section: Eejp 1 (2020)mentioning

confidence: 99%

Section: Eejp 1 (2020)mentioning

confidence: 99%

Section: Eejp 1 (2020)mentioning

confidence: 99%

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Effect of Kind of Deformation on Young's Modulus, Damage Parameter, Texture and Structure of Alloy Mg – 5% Li (wt)

Usov

Brokmeier²,

Shkatulyak

et al. 2020

EEJP

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Recrystallization of bulk nanostructured magnesium alloy AZ31 after severe plastic deformation: an in situ diffraction study

Liss,

Han,

Blankenburg

et al. 2024

J Mater Sci

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The magnesium alloy AZ31, which has undergone high-pressure torsion processing, was subjected to in situ annealing microbeam synchrotron high-energy X-ray diffraction and compared to the as-received rolled sheet material that was investigated through in situ neutron diffraction. While the latter only exhibits thermal expansion and minor recovery, the nanostructured specimen displays a complex evolution, including recovery, strong recrystallization, phase transformations, and various regimes of grain growth. Nanometer-scale grain sizes, determined using Williamson–Hall analysis, exhibit seamless growth, aligning with the transition to larger grains, as assessed through the occupancy of single-grain reflections on the diffraction rings. The study uncovers strain anomalies resulting from thermal expansion, segregation of Al atoms, and the kinetics of vacancy creation and annihilation. Notably, a substantial number of excess vacancies were generated through high-pressure torsion and maintained for driving the recrystallization and forming highly activated volumes for diffusion and phase precipitation during heating. The unsystematic scatter observed in the Williamson–Hall plot indicates high dislocation densities following severe plastic deformation, which significantly decrease during recrystallization. Subsequently, dislocations reappear during grain growth, likely in response to torque gradients in larger grains. It is worth noting that the characteristics of unsystematic scatter differ for dislocations created at high and low temperatures, underscoring the strong temperature dependence of slip system activation. Graphical Abstract

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Evolution of reinforcement distribution in Al–B4C composites during accumulative roll bonding

2011

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Grain Size, Size‐Distribution and Dislocation Structure from Diffraction Peak Profile Analysis

Cited by 3 publications

References 37 publications

Effect of Kind of Deformation on Young's Modulus, Damage Parameter, Texture and Structure of Alloy Mg – 5% Li (wt)

Effect of Kind of Deformation on Young's Modulus, Damage Parameter, Texture and Structure of Alloy Mg – 5% Li (wt)

Recrystallization of bulk nanostructured magnesium alloy AZ31 after severe plastic deformation: an in situ diffraction study

Evolution of reinforcement distribution in Al–B4C composites during accumulative roll bonding

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