Evolution of dislocation structure in neutron irradiated Zircaloy-2 studied by synchrotron x-ray diffraction peak profile analysis

Seymour, Thomas; Frankel, Philipp; Balogh, Levente; Ungár, Tamás; Thompson, Stephen P.; Jädernäs, Daniel; Romero, Javier; Hallstadius, Lars; Daymond, Mark R.; Ribárik, Gabor; Preuß, Michael

doi:10.1016/j.actamat.2016.12.031

Cited by 77 publications

(51 citation statements)

References 56 publications

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“…Hence, if the measured q 1 is less than 0 the method will provide <a> dislocations as the dominant dislocation type, and if the measure q 2 is more than 0 the value of <a> dislocations will be predicted to be close to 100%. Modifications to the approach have been made by some researchers to only include expected dislocation types; such as done by Seymour et al for neutron irradiated zirconium alloys [31] using calculated contrast factor values for common dislocations found in the alloy, but the approach thereafter is essentially the same.…”

Section: Hexagonal Close Packed Alloysmentioning

confidence: 99%

“…This can be seen from Equation (1), which shows a feature of DPPA methods that they can only obtain the product ρC hkl and not the values individually. The homogeneous contrast factor approach has been widely used in HCP alloys to quantify the fraction of dislocations with different Burgers vectors [3,22,[29][30][31][32][33]., or relative amounts of slip systems with different slip planes [3,30].…”

Section: Planar Faultsmentioning

confidence: 99%

“…The second approach (Figure 18d) is a slight modification to the previous one, whereby the available slip system types are reduced to those expected to be the most important types in titanium [83]. This type of approach, involving reducing the available slip systems has been used by different authors [31,85]. These approaches are generally only used to predict the quantity of different Burgers vector types, <a>, <c+a> and <c>; although Mathis et al [85] also used the approach to find the relative quantity of two different slip system types, prismatic and basal <a>.…”

Section: Homogeneous Approachmentioning

confidence: 99%

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Peak Broadening Anisotropy and the Contrast Factor in Metal Alloys

Simm

2018

Crystals

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Diffraction peak profile analysis (DPPA) is a valuable method to understand the microstructure and defects present in a crystalline material. Peak broadening anisotropy, where broadening of a diffraction peak doesn't change smoothly with 2θ or d-spacing, is an important aspect of these methods. There are numerous approaches to take to deal with this anisotropy in metal alloys, which can be used to gain information about the dislocation types present in a sample and the amount of planar faults. However, there are problems in determining which method to use and the potential errors that can result. This is particularly the case for hexagonal close packed (HCP) alloys. There is though a distinct advantage of broadening anisotropy in that it provides a unique and potentially valuable way to develop crystal plasticity and work-hardening models. In this work we use several practical examples of the use of DPPA to highlight the issues of broadening anisotropy. of 31where, D is the crystal size, K Sch is the Scherrer constant (often taken as 0.9 for spherical crystals), g is the reciprocal of the d-spacing of a peak, f m is a function related to the arrangement of dislocations (and represents how the arrangement of groups of dislocations influence their total strain), ρ is the dislocation density and C hkl is the average contrast factor of dislocations in grains that contribute to the hkl diffraction peak. In Equation 1 and other DPPA approaches, C hkl is assumed to be the only term that accounts for broadening anisotropy and its value is required to be able to obtain the dislocation density.TEM to be able to identify details of dislocations [15,16], especially in cases when g.b=0 does not lead to vanishing contrast or due to practicalities of rotating a sample. In the same manner, the diffraction broadening caused by a dislocation varies depending on the diffraction vector, and can be calculated by modelling the dislocation's displacement field. The contribution of a dislocation's displacement field to the broadening of different diffraction profiles is through what is known as the contrast (or orientation) factor of dislocations. The contrast factor of an individual dislocation is dependent on the angles between the diffraction vector and the vectors that define the dislocation: it's Burgers vector (b), slip plane normal (n), and dislocation line (s). The contrast factor of an individual dislocation can be calculated using the computer program ANIZC [17]. For example, the edge dislocation in Figure 2 has a contrast factor of 0.46 when g is [110] and parallel to the dislocations Burgers vector. The value is 0.00 when g is parallel to the slip line ([11 2]) and 0.05 when g is parallel to the slip plane normal ([1 11]).

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Section: Hexagonal Close Packed Alloysmentioning

confidence: 99%

Section: Planar Faultsmentioning

confidence: 99%

Section: Homogeneous Approachmentioning

confidence: 99%

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Peak Broadening Anisotropy and the Contrast Factor in Metal Alloys

Simm

2018

Crystals

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“…As the study of analytical quantity of dislocation densities are an extremely great deal with TEM investigation. The study of dislocation bend in irradiated substances is also constrained using TEM analysis [33]. The concept of Diffraction peak profile investigation is a highly useful technique to explore the dislocation density, dislocation structure, and population distribution in the technically deformed objects due to such a reason which is a foundation to be a complementary procedure to TEM analysis [34,35].…”

Section: Introductionmentioning

confidence: 99%

Comparison of average crystallite size by X-ray peak broadening and Williamson–Hall and size–strain plots for VO2+ doped ZnS/CdS composite nanopowder

Madhavi

2019

SN Appl. Sci.

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The paper deals with the exhaustive study and analysis of VO 2+ ions doped ZnS/CdS composite nanopowder with the help of X-ray peak profile analysis (XPPA). The investigation has been carried out by applying a distinct pattern of Williamson-Hall (W-H) approach viz., uniform deformation model, the uniform stress deformation model and uniform deformation energy density model, and size strain plot (SSP). Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscope and energy dispersive spectra (EDS) and transmission electron microscope (TEM) techniques. The XRD study is high manipulated order and fundamental focus is on phase identification, with some analysis on advanced concepts such as crystallite size and lattice strain have been estimated using the modified form of the W-H methods. XRD pattern confirmed that the structure of the sample belongs to the cubic system. The variation of lattice constant (a) with dopant is assigned to Vegard's law. The root means square strain was identified from the interionic separation and lattice strain assumed on W-H models. FT-IR spectrum exhibited characteristic vibrational modes of Zn and Cd ions along with other bands. EDS analysis gives information about the elemental composition in the present sample. The shape of VO 2+ ions doped ZnS/CdS composite nanopowder was spherical in TEM images. The result showed that there was a good agreement in the particle size obtained from the W-H method and the SSP method with TEM images.

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“…Such R e values approach the lower limit of continuum theory not far from atomic distances [50,51]. In neutron [52] or proton [53] irradiated Zr alloys the dislocation line density can reach a few times 10 16 m -2 while the M value is around M1 or smaller. With these values R e 2 to 4 nm.…”

Section: Stabilizing the Fluctuations Of The Physical Parameters Whenmentioning

confidence: 73%

Global optimum of microstructure parameters in the CMWP line-profile-analysis method by combining Marquardt-Levenberg and Monte-Carlo procedures

Ribárik

Jóni

Ungár

2019

Journal of Materials Science & Technology

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Line profile analysis of X-ray and neutron diffraction patterns is a powerful tool for determining the microstructure of crystalline materials. The Convolutional-Multiple-Whole-Profile (CMWP) procedure is based on physical profile functions for dislocations, domain size, stacking faults and twin boundaries. Order dependence, strain anisotropy, hkl dependent broadening of planar defects and peak shape are used to separate the effect of different lattice defect types. The Marquardt-Levenberg (ML) numerical optimization procedure has been used successfully to determine crystal defect types and densities. However, in more complex cases like hexagonal materials or multiple phases the ML procedure alone reveals uncertainties. In a new approach the ML and a Monte-Carlo statistical method are combined in an alternative manner. The new CMWP procedure eliminates uncertainties and provides globally optimized parameters of the microstructure.

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Evolution of dislocation structure in neutron irradiated Zircaloy-2 studied by synchrotron x-ray diffraction peak profile analysis

Cited by 77 publications

References 56 publications

Peak Broadening Anisotropy and the Contrast Factor in Metal Alloys

Peak Broadening Anisotropy and the Contrast Factor in Metal Alloys

Comparison of average crystallite size by X-ray peak broadening and Williamson–Hall and size–strain plots for VO2+ doped ZnS/CdS composite nanopowder

Global optimum of microstructure parameters in the CMWP line-profile-analysis method by combining Marquardt-Levenberg and Monte-Carlo procedures

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