Contrast factors of irradiation-induced dislocation loops in hexagonal materials

Balogh, Levente; Long, Fei; Daymond, Mark R.

doi:10.1107/s1600576716018136

Cited by 20 publications

(10 citation statements)

References 75 publications

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“…In order to determine the real dislocation density (not only the formal one given above), the contrast factors of the different possible prismatic loops have to be determined. In a detailed investigation, Balogh et al (2016) numerically calculated the average contrast factors for different possible loops. The calculation was based on the ANIZC software package (Borbé ly et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Evolution of dislocation microstructure in irradiated Zr alloys determined by X-ray peak profile analysis

et al. 2021

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During neutron irradiation of metals, owing to the enhanced number of vacancies and interstitial atoms, the climb motion of dislocations becomes significant at room temperature, leading to a recrystallization of the material. Moreover, the vacancies and interstitial atoms tend to form prismatic dislocation loops that play a crucial role in the plastic properties of the materials. X-ray peak profile analysis is an efficient nondestructive method to determine the properties of dislocation microstructure. In the first half of this article, the foundation of the asymptotic peak broadening theory and the related restricted-moments peak-evaluation method is summarized. After this, the microstructural parameters obtained by X-ray peak profile analysis are reported for irradiated E110 and E110G Zr alloys used as cladding material in the nuclear industry.

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Section: Discussionmentioning

confidence: 99%

Evolution of dislocation microstructure in irradiated Zr alloys determined by X-ray peak profile analysis

et al. 2021

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“…The shift notations are shown in Fig. 6(b) on the (10.2) reflection of a Zircaloy-2 specimen proton-irradiated to 4.7 dpa at 350 C. In equations ( 14a) and (14b), C hkl Loops are the hkl-dependent average contrast factors for dislocation loops (Balogh et al, 2016). They are shown for dislocation loops in Zr in Fig.…”

Section: Satellites Around the Fundamental Bragg Reflections Produced By Irradiation-induced Dislocation Loopsmentioning

confidence: 99%

“…In addition to IIG, the formation of dislocation loops leads to hardening and embrittlement of the material (Northwood et al, 1979;Griffiths, 1988;Lemaignan, 2012). Though the vast majority of microstructure investigations during IIG have been based on TEM (Griffiths et al, 1983;Carpenter et al, 1988), X-ray and neutron LPA have also been applied to follow the IIG process (Griffiths et al, 1992(Griffiths et al, , 2002Griffiths, 2008;Balogh et al, 2012Balogh et al, , 2016Harte et al, 2015;Seymour et al, 2017;Topping et al, 2019). Harte et al (2015), Balogh et al (2016), Seymour et al (2017) and Topping et al (2019) carried out systematic TEM and X-ray LPA analysis on different neutron-or proton-irradiated Zr alloy specimens.…”

Section: Introductionmentioning

confidence: 99%

“…The dislocation contrast factors play a crucial role in the CMWP procedure. Balogh et al (2016) evaluated contrast factors for irradiation-induced dislocation loops in Zr. Using these contrast factors we develop a simple and straightforward method to determine the dislocation density fractions pertaining to haiand hci-type dislocation loops.…”

Section: Introductionmentioning

confidence: 99%

“…Although X-ray LPA has proved to be an excellent and effective complementary tool to TEM in determining dislocation densities and arrangements, crystallite sizes, and planar defect densities in crystalline materials with very different structures (Warren, 1959;Wilkens, 1970;Borbé ly & Groma, 2001;Scardi & Leoni, 2002;, some genuine problems and apparent discrepancies arise in data for irradiated materials such as irradiated zirconium alloys (Griffiths et al, 1992(Griffiths et al, , 2002Griffiths, 2008;Balogh et al, 2012Balogh et al, , 2016Balogh et al, , 2018Harte et al, 2015;Seymour et al, 2017;Topping et al, 2018Topping et al, , 2019):…”

Section: Introductionmentioning

confidence: 99%

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Characterizing dislocation loops in irradiated polycrystalline Zr alloys by X-ray line profile analysis of powder diffraction patterns with satellites

Ungár¹,

Ribárik²,

Topping³

et al. 2021

J Appl Crystallogr

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This work extends the convolutional multiple whole profile (CMWP) line profile analysis (LPA) procedure to determine the total dislocation density and character of irradiation-induced dislocation loops in commercial polycrystalline Zr specimens. Zr alloys are widely used in the nuclear industry as fuel cladding materials in which irradiation-induced point defects evolve into dislocation loops. LPA has long been established as a powerful tool to determine the density and nature of lattice defects in plastically deformed materials. The CMWP LPA procedure is based on the Krivoglaz–Wilkens theory in which the dislocation structure is characterized by the total dislocation density ρ and the dislocation arrangement parameter M. In commercial Zr alloys irradiation-induced dislocation loops broaden the peak profiles, mainly in the tail regions, and occasionally generate small satellites next to the Bragg peaks. In this work, two challenges in powder diffraction patterns of irradiated Zr alloys are solved: (i) determination of the M values from the long tail regions of peaks has been made unequivocal and (ii) satellites have been fitted separately, using physically well established principles, in order to exclude them from the dislocation determination process. Referring to the theory of heterogeneous dislocation distributions, determination of the total dislocation density from the main peaks free of satellites has been justified. The dislocation loop structure has been characterized by the total dislocation density of loops and the M parameter correlated to the dipole character of dislocation loops. The extended CMWP procedure is applied to determine the total dislocation density, the dipole character of dislocation loops, and the fractions of 〈a〉- and 〈c〉-type loops in proton- or neutron-irradiated polycrystalline Zr alloys used in the nuclear energy industry.

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Microstructural Evolution of Tantalum During Deformation and Subsequent Annealing

Brown,

Anghel,

Clausen

et al. 2024

Metall Mater Trans A

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Microstructure-aware models are necessary to predict the behavior of material based on process knowledge or to extrapolate mechanical properties of materials to environmental conditions which are not easily reproduced in the laboratory, e.g., nuclear reactor environments. Elemental Ta provides a relatively simple BCC system in which to develop a microstructural understanding of deformation processes which can then be applied to more complicated BCC alloys. In situ neutron diffraction during compressive deformation and subsequent heat treatment have been used to monitor the evolution of microstructural features in Ta throughout simulated processing steps. Crystallographic texture and dislocation density are determined as a function of first plastic strain, then temperature. Lattice strains are determined and attributed to stresses at macroscopic, grain and dislocation length scales. The increase of the dislocation density through deformation and subsequent recovery during heat treatment is monitored through the changing diffraction line profile. Also, randomization of the texture is used as a signature of recrystallization. The recovery of dislocations through annihilation is not observed to depend on the initial dislocation density in the range studied here. In contrast, recrystallization is observed to depend strongly on the initially dislocation density.

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Contrast factors of irradiation-induced dislocation loops in hexagonal materials

Cited by 20 publications

References 75 publications

Evolution of dislocation microstructure in irradiated Zr alloys determined by X-ray peak profile analysis

Evolution of dislocation microstructure in irradiated Zr alloys determined by X-ray peak profile analysis

Characterizing dislocation loops in irradiated polycrystalline Zr alloys by X-ray line profile analysis of powder diffraction patterns with satellites

Microstructural Evolution of Tantalum During Deformation and Subsequent Annealing

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