Stress Gradient Induced Strain Localization in Metals: High Resolution Strain Cross Sectioning via Synchrotron X-Ray Diffraction

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
M. Croft ◽  
N. Jisrawi ◽  
Z. Zhong ◽  
K. Horvath ◽  
R. L. Holtz ◽  
...  
Keyword(s):  
Strain Localization ◽  
High Spatial Resolution ◽  
Stress Gradient ◽  
Nonlinear Effects ◽  
Engineering Science ◽  
Optical Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Materials Engineering ◽  
Engineering Problems

Strain localization in the presence of a stress gradient is a phenomenon common to many systems described by continuum mechanics. Variations of this complex phenomenon lead to interesting nonlinear effects in materials/engineering science as well as in other fields. Here, the synchrotron based energy dispersive x-ray diffraction (EDXRD) technique is used for high spatial resolution profiling of both compression and tension induced strain localization in important materials/engineering problems. Specifically, compression induced strain localization in shot peened materials and tension induced strain localization in the plastic zones adjoining the faces of a fatigue crack are profiled. The utility of the EDXRD synchrotron technique for nondestructively cross-sectioning strain variations on small length scales (down to 10–20μm) is described. While the strain field profiling relies on the shift of the Bragg lines, the data show that plastic deformation regions can also consistently be seen in the broadening of the Bragg peaks through the full width at half maximum parameter. Quantitative correlations between the synchrotron based x-ray determined deformations and surface deformations, as measured by optical surface height profiling, are also made.

Micro Diffraction Imaging of Bulk Polycrystalline Materials

2006 ◽  
Vol 524-525 ◽  
pp. 273-278
Author(s):  
Thomas Wroblewski ◽  
A. Bjeoumikhov ◽  
Bernd Hasse
Keyword(s):  
High Spatial Resolution ◽  
Polycrystalline Materials ◽  
X Rays ◽  
X Ray Diffraction ◽  
Short Sample ◽  
X Ray ◽  
Detector Distance ◽  
Transmission Geometry ◽  
Diffraction Imaging ◽  
Position Sensitive

X-ray diffraction imaging applies an array of parallel capillaries in front of a position sensitive detector. Conventional micro channel plates of a few millimetre thickness have successfully been used as collimator arrays but require short sample to detector distances to achieve high spatial resolution. Furthermore, their limited absorption restricts their applications to low energy X-rays of around 10 keV. Progress in the fabrication of long polycapillaries allows an increase in the sample to detector distance without decreasing resolution and the use of high X-ray energies enables bulk investigations in transmission geometry.

scholarly journals Stress Gradient Analysis by Noncomplanar x-Ray Diffraction and Corresponding Refraction Correction

2014 ◽  
Vol 996 ◽  
pp. 162-168 ◽  
Author(s):  
Andrei Benediktovitch ◽  
Tatjana Ulyanenkova ◽  
Jozef Keckes ◽  
Alex Ulyanenkov
Keyword(s):  
Residual Stress ◽  
Gradient Analysis ◽  
Stress Gradient ◽  
X Ray Diffraction ◽  
Large Area ◽  
Present Contribution ◽  
Nondestructive Technique ◽  
X Ray ◽  
Tin Coatings ◽  
Measurement Geometry

X-ray residual stress analysis is a widespread nondestructive technique to investigate the residual stress and residual stress gradient in thin films and protective coatings.In the present contribution we introduce a new method based on the noncomplanar measurement geometry that allow to span large area of sin2ψ and penetration depth values without sample inclination. The refraction correction and absorption is considered in details for the noncomplanar measurements. The proposed technique is applied to determine stress gradients of blasted hard TiN coatings.

Influence of Surface Roughness on the Quality of Data Obtained by Pseudo-Grazing Incidence X-Ray Diffraction

2006 ◽  
Vol 514-516 ◽  
pp. 1618-1622 ◽  
Author(s):  
Maria José Marques ◽  
J.C.P. Pina ◽  
A. Morão Dias
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Stress Gradient ◽  
Roughness Parameter ◽  
Diffraction Method ◽  
Grazing Incidence ◽  
Bragg Diffraction ◽  
X Ray Diffraction ◽  
Residual Surface Stress ◽  
X Ray

The conventional Bragg diffraction geometry, normally used to characterize the residual surface stress state, it is not suitable to evaluate surface treated materials and thin films. The X-ray path lengths through a surface layer or thin film are too short to produce adequate diffraction intensities in relation to the bulk or the substrate. Another limitation of the conventional technique appears when a residual stress gradient is present in the irradiated surface. The technique only enables the evaluation of the mean value of this gradient. In these cases, a recently proposed Pseudo-Grazing Incident X-ray Diffraction method would be better applicable. In this study, the Pseudo-Grazing Incidence X-ray Diffraction is applied to characterize the residual stress depth profiles of several AISI 4140 samples, which were prepared, by mechanical polishing and grinding, in order to present different surface roughness parameters, Ra. The experimental results lead to the conclusion that the surface roughness limits the application of the Pseudo-Grazing Incidence methodology to a minimum X-ray incident angle. This angle is the one that enables a mean X-ray penetration depth with the same order of magnitude of the sample surface roughness parameter, Ra.

Non-Destructive Residual Stress Analysis of Induction Hardened Components by Neutron and X-Ray Diffraction

2013 ◽  
Vol 768-769 ◽  
pp. 420-427 ◽  
Author(s):  
Jeremy Epp ◽  
Thilo Pirling ◽  
Thomas Hirsch
Keyword(s):  
Residual Stress ◽  
Chemical Composition ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Stress Gradient ◽  
X Ray Diffraction ◽  
Neutron Measurement ◽  
X Ray ◽  
Layer Removal ◽  
Residual Stress Analysis

In this paper the microstructural and residual-stress analysis of an induction hardened plate of medium carbon steel is described. The stress gradient was determined using laboratory X-ray diffraction (IWT, Bremen, Germany) and neutron strain scanning (ILL, Grenoble, France). Due to slight variations of chemical composition in the depth, matchstick like (cross section 2×2mm²) d0-reference samples were prepared from a similarly treated sample. The d0shift induced by variation of chemical composition was measured by neutron and by X-ray diffraction along the strain free direction (sin²ψ*) and used for the evaluation of the neutron stress calculation. The d0distribution obtained from the neutron measurement did not appear reliable while the method using X-ray diffraction seems to be an efficient and reliable method to determine d0profiles in small samples. The evaluation of neutron measurements was then done using the X-ray diffraction d0distribution. High compressive residual stresses were measured in the hardened layer followed by high tensile residual stresses in the core. A comparison of the neutron measurements with X-ray diffraction (XRD) depth profiles obtained after successive layer removal showed that both methods give similar results. However, these investigations opened the question about the direct comparison of the residual stresses obtained by neutron and XRD. Indeed, a correction of the neutron data regarding the residual stresses in thickness direction might be necessary as these are released in the case of X-ray diffraction measurements after layer removal.

scholarly journals Interaction of Corroding Iron with Eight Bentonites in the Alternative Buffer Materials Field Experiment (ABM2)

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 907
Author(s):  
Paul Wersin ◽  
Jebril Hadi ◽  
Andreas Jenni ◽  
Daniel Svensson ◽  
Jean-Marc Grenèche ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Hard Rock ◽  
High Spatial Resolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rock Laboratory ◽  
Reducing Conditions ◽  
Buffer Material ◽  
High Level ◽  
Redox Evolution

Bentonite, a common smectite-rich buffer material, is in direct contact with corroding steel in many high-level radioactive waste repository designs. The interaction of iron with the smectite-rich clay may affect its swelling and sealing properties by processes such as alteration, redox reactions and cementation. The chemical interactions were investigated by analysing the Fe/clay interfaces of eight bentonite blocks which had been exposed to temperatures up to 130 °C for five years in the ABM2 borehole at the Äspö Hard Rock Laboratory managed by the Swedish Nuclear Fuel and Waste Management Co (SKB). Eleven interface samples were characterised by high spatial resolution methods, including scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and μ-Raman spectroscopy as well as by “bulk” methods X-ray diffraction, X-ray fluorescence and 57Fe Mössbauer spectrometry. Corrosion induced an iron front of 5–20 mm into the bentonite, except for the high-Fe bentonite where no Fe increase was detected. This Fe front consisted mainly of ferric (oxyhydr)oxides in addition to the structural Fe in the smectite fraction which had been partially reduced by the interaction process. Fe(II) was also found to extend further into the clay, but its nature could not be identified. The consistent behaviour is explained by the redox evolution, which shifts from oxidising to reducing conditions during the experiment. No indication of smectite alteration was found.

scholarly journals Material Removal, Correction and Laboratory X-Ray Diffraction

2014 ◽  
Vol 996 ◽  
pp. 181-186 ◽  
Author(s):  
Eric Wasniewski ◽  
Baptiste Honnart ◽  
Fabien Lefebvre ◽  
Eric Usmial
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Stress Field ◽  
Residual Stresses ◽  
Material Removal ◽  
Stress Gradient ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Residual Stresses ◽  
Residual Stress Gradient

Laboratory X-ray diffraction is commonly used for surface residual stresses determination. Nevertheless, the in-depth residual stress gradient also needs to be known. Chemical or electro-polishing method is generally used for material removal. However, material removal may seek a new equilibrium and stress field may change in such a way that experimental residual stress values must be corrected. Different methods exist to account for the residual stress relaxation associated with the material removal operation and will be discussed in this paper.

Focusing Optics for High-Energy X-ray Diffraction

1998 ◽  
Vol 5 (3) ◽  
pp. 226-231 ◽  
Author(s):  
U. Lienert ◽  
C. Schulze ◽  
V. Honkimäki ◽  
Th. Tschentscher ◽  
S. Garbe ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
High Spatial Resolution ◽  
Dispersion Compensation ◽  
High Energy ◽  
Polycrystalline Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Momentum Resolution ◽  
Potential Applications ◽  
Band Pass

Novel focusing optical devices have been developed for synchrotron radiation in the energy range 40–100 keV. Firstly, a narrow-band-pass focusing energy-tuneable fixed-exit monochromator was constructed by combining meridionally bent Laue and Bragg crystals. Dispersion compensation was applied to retain the high momentum resolution despite the beam divergence caused by the focusing. Next, microfocusing was achieved by a bent multilayer arranged behind the crystal monochromator and alternatively by a bent Laue crystal. A 1.2 µm-high line focus was obtained at 90 keV. The properties of the different set-ups are described and potential applications are discussed. First experiments were performed, investigating with high spatial resolution the residual strain gradients in layered polycrystalline materials. The results underline that focused high-energy synchrotron radiation can provide unique information on the mesoscopic scale to the materials scientist, complementary to existing techniques based on conventional X-ray sources, neutron scattering or electron microscopy.

An X-Ray Diffraction Method to Determine Stress at Constant Penetration/Information Depth

2006 ◽  
Vol 524-525 ◽  
pp. 13-18 ◽  
Author(s):  
A. Kumar ◽  
U. Welzel ◽  
M. Wohlschlögel ◽  
W. Baumann ◽  
Eric J. Mittemeijer
Keyword(s):  
Penetration Depth ◽  
Stress Gradient ◽  
Diffraction Method ◽  
Nickel Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Measurements ◽  
Information Depth ◽  
Depth Control ◽  
Sputter Deposited

A rigorous strategy for (X-ray) diffraction stress measurements at fixed penetration/information depths is described. Thereby errors caused by lack of penetration-depth control in traditional (X-ray) diffraction (sin2ψ) measurements are annulled. The ranges of accessible penetration/information depths and experimental aspects are briefly discussed. The power of the method is illustrated by the analysis of an only small stress gradient in a sputter-deposited nickel layer.

The Role of Cation Point Defects and Oxygen Interstitials on Modulations in Undoped and Doped Bi-Sr-Ca-Cu-O Superconductors

1990 ◽  
Vol 209 ◽  
Author(s):  
P. L. Gai ◽  
M. A. Subramanian ◽  
A. W. Sleight
Keyword(s):  
Electron Diffraction ◽  
Point Defects ◽  
High Spatial Resolution ◽  
Lattice Mismatch ◽  
Hole Concentration ◽  
Microstructural Analysis ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
X Ray

ABSTRACTVariations in superstructure modulations and transition tempeartures (Tc) in undoped and yttrium-doped Bi2Sr2CaCu2O8 (2212) superconductors annealed in different environments have been examined by microstructural analysis. The hole concentration is changed either by annealing the samples in reducing or oxidizing environments, or by partial substitution of Y3+ cations on the Ca-sites. Systematic investigations of the 2212 samples annealed in both the reducing (nitrogen) and oxidizing (oxygen) environments show commensurate and incommensurate modulations, respectively, and a decrease of Tc in oxygen. Commensurate modulations have also been found for samples prepared entirely in nitrogen. High spatial resolution microanalysis reveals that the modulations are insensitive to cation point defects. These results indicate that modulations are intrinsic to the 2212 materials and that they are caused by the lattice mismatch between the perovskite and Bi-O layers. Such periodic variations in interplanar spacings are expected to lead to satellite spots as observed in electron diffraction. The results are consistent with single crystal X-ray diffraction studies reported in the literature. In the Y- doped samples Tc values are similar in Bi2Sr2Ca1-xYxCu2O8 for x=0.2, in both the environments, but decrease with increasing value of x.

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