Measurement of Strain and Lattice Rotation in the Particle Deformation Zone

2013 ◽  
Vol 753 ◽  
pp. 21-24
Author(s):  
Lawrence C.L. Ko ◽  
Joao Quinta da Fonseca
Keyword(s):  
Deformation Zone ◽  
Electron Backscatter Diffraction ◽  
Local Deformation ◽  
Image Correlation ◽  
Lattice Rotation ◽  
Particle Deformation ◽  
Local Lattice ◽  
Measured Deformation ◽  
Backscatter Diffraction ◽  
First Time

It is known that there is lattice rotation around the particles after deformation, in a so-called Particle Deformation Zone (PDZ), which is thought to be important in randomizing the texture after recrystallization though Particle Stimulated Nucleation (PSN). However, the role of the local distribution of stored energy and its link to local lattice rotation is not well understood, making it impossible to successfully predict PSN efficiency. Here, we present a new method for studying the deformation around particles with the use of Digital Image Correlation (DIC) of High-Resolution Scanning Electron Microscopy (HRSEM) image and Electron BackScatter Diffraction (EBSD) map. Combining these two techniques makes it possible, for the first time, to relate the local deformation fields to remnant changes in local lattice orientation. Initial measurements are made on a model Al-Si alloy deformed in plane-strain condition by channel die compression up to 30%. Our analysis shows that the material deforms heterogeneously with high levels of deformation localized along slip bands. EBSD analysis shows that the lattice distortion in these bands is minimal. The HRDIC analysis clearly shows particles interrupt the slip banding. Local lattice rotation measured by EBSD is considerably less than expected from the measured deformation.

scholarly journals Using electron backscatter diffraction to measure full crystallographic orientation in Antarctic land-fast sea ice

2018 ◽  
Vol 64 (247) ◽  
pp. 771-780 ◽  
Author(s):  
PAT WONGPAN ◽  
DAVID J. PRIOR ◽  
PATRICIA J. LANGHORNE ◽  
KATHERINE LILLY ◽  
INGA J. SMITH
Keyword(s):  
Sea Ice ◽  
Crystallographic Orientation ◽  
Electron Backscatter Diffraction ◽  
Preferred Orientation ◽  
Angle Distribution ◽  
Crystal Preferred Orientation ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
First Time ◽  
Platelet Ice

ABSTRACTWe have mapped the full crystallographic orientation of sea ice using electron backscatter diffraction (EBSD). This is the first time EBSD has been used to study sea ice. Platelet ice is a feature of sea ice near ice shelves. Ice crystals accumulate as an unconsolidated sub-ice platelet layer beneath the columnar ice (CI), where they are subsumed by the advancing sea–ice interface to form incorporated platelet ice (PI). As is well known, in CI the crystal preferred orientation comprises dominantly horizontal c-axes, while PI has c-axes varying between horizontal and vertical. For the first time, this study shows the a-axes of CI and PI are not random. Misorientation analysis has been used to illuminate the possible drivers of these alignments. In CI the misorientation angle distribution from random pairs and neighbour pairs of grains are indistinguishable, indicating the distributions are a consequence of crystal preferred orientation. Geometric selection during growth will develop the a-axis alignment in CI if ice growth in water is fastest parallel to the a-axis, as has previously been hypothesised. In contrast, in PI random-pair and neighbour-pair misorientation distributions are significantly different, suggesting mechanical rotation of crystals at grain boundaries as the most likely explanation.

Spatial resolution measurements of electron backscatter diffraction patterns (EBSPs) in the scanning electron microscope

1990 ◽  
Vol 48 (4) ◽  
pp. 404-405 ◽  
Author(s):  
Jarle Hjelen ◽  
Erik Nes
Keyword(s):  
Electron Beam ◽  
Spatial Resolution ◽  
Electron Backscatter Diffraction ◽  
Line Pattern ◽  
Bulk Specimen ◽  
Local Lattice ◽  
Diffraction Patterns ◽  
Backscatter Diffraction ◽  
Stationary Electron ◽  
Better Than

In the EBSP method the stationary electron beam hits a highly tilted bulk specimen in the SEM. The backscattered Bragg diffracted electrons form the Kikuchi line pattern on a phosphor screen. Since the first EBSP experiments were carried out in 1973, this technique has been further developed to determine crystal orientations in connection with texture development in aluminium. Using the EBSP method to calculate local lattice curvatures in heavily deformed aluminium, the spatial resolution has to be better than the selected area channeling pattern (SACP) method.The EBSP resolution (d) was measured by moving the electron beam digitally across grain boundaries in an aluminium sample. The resolution was defined to be the overlapping distance between two diffraction patterns.

Stabilisation of Aragonite: The Role of Mg2+ and Other Impurity Ions

2019 ◽  
Author(s):  
Matthew Boon ◽  
William Rickard ◽  
Andrew Rohl ◽  
Franca Jones
Keyword(s):  
Electron Backscatter Diffraction ◽  
Crystal Formation ◽  
Sulfate Ions ◽  
Inorganic Systems ◽  
Sodium Magnesium ◽  
Stable Product ◽  
The Stability ◽  
Backscatter Diffraction ◽  
First Time

Aragonite formation and stabilisation in seawater is still an area of active investigation since the thermodynamically stable product at room temperature is calcite. In this manuscript, purely inorganic systems that were found to stabilise aragonite were analysed by various techniques. Dynamic Light Scattering was used to characterise the nucleation behaviour of the system and it was found that the presence of magnesium ions during crystal formation inhibits nucleation overall, not just calcite nucleation. In addition, it was found that sulfate is not necessary to stabilise aragonite. Microanalysis by energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) revealed that the aragonite that was formed had a disordered core with, sodium, magnesium and sulfate ions incorporated into the structure. To the best of the authors’ knowledge this is the first time an ACC core in aragonite has been visualised in a completely abiotic, synthetic system (in the absence of organic molecules). Inclusion of these impurities into the structure may explain the stability of aragonite in natural seawaters.

scholarly journals Crack nucleation using combined crystal plasticity modelling, high-resolution digital image correlation and high-resolution electron backscatter diffraction in a superalloy containing non-metallic inclusions under fatigue

2016 ◽  
Vol 472 (2189) ◽  
pp. 20150792 ◽  
Author(s):  
Tiantian Zhang ◽  
Jun Jiang ◽  
Ben Britton ◽  
Barbara Shollock ◽  
Fionn Dunne
Keyword(s):  
Fatigue Crack ◽  
Crystal Plasticity ◽  
Electron Backscatter Diffraction ◽  
Crack Nucleation ◽  
Image Correlation ◽  
Fatigue Crack Nucleation ◽  
Resolution Electron ◽  
Electron Backscatter ◽  
Mechanistic Basis ◽  
Backscatter Diffraction

A crystal plasticity finite-element model, which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy, has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to use the crystal plasticity model in conjunction with direct measurement at the microscale using high (angular) resolution-electron backscatter diffraction (HR-EBSD) and high (spatial) resolution-digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone, and the interfacial strength was determined to be in the range of 1270–1480 MPa.

Electron Backscatter Diffraction in Conservation Science: Phase Identification of Pigments in Paint Layers

2013 ◽  
Vol 19 (4) ◽  
pp. 921-928 ◽  
Author(s):  
A. Gambirasi ◽  
L. Peruzzo ◽  
S. Bianchin ◽  
M. Favaro
Keyword(s):  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Small Samples ◽  
Phase Identification ◽  
Conservation Science ◽  
Atomic Number Density ◽  
Electron Backscatter ◽  
Mohs Hardness ◽  
Backscatter Diffraction ◽  
First Time

AbstractElectron backscatter diffraction (EBSD) was used in Conservation Science for characterization of ancient materials collected from works of art. The results demonstrate the feasibility of EBSD analysis on heterogeneous matrices as very small samples of paint layers collected from paintings. Two reference pigments were selected from those used by artists to investigate the relationship existing between EBSD pattern quality and properties of the investigated material (i.e., average atomic number, density, and Mohs hardness). The technique was also tested to investigate the pigment phases on two real samples collected from Romanino's Santa Giustina altarpiece, an oil on wood painting dated 1514 (Civic Museum, Padova, Italy). Results show for the first time the acquisition of EBSD patterns from painting samples mounted in resin, i.e., painting cross sections, opening a new powerful tool to elucidate the pigment phases avoiding large sampling on works of arts and to further study the complex mechanisms of pigment deterioration.

scholarly journals Aluminum-to-Steel Cladding by Explosive Welding

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1062 ◽  
Author(s):  
Gustavo H. S. F. L. Carvalho ◽  
Ivan Galvão ◽  
Ricardo Mendes ◽  
Rui M. Leal ◽  
Altino Loureiro
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Explosive Welding ◽  
Electron Backscatter Diffraction ◽  
Dissimilar Materials ◽  
Image Correlation ◽  
Low Density ◽  
Explosive Mixture ◽  
Successful Testing ◽  
Backscatter Diffraction

The production of aluminum-carbon steel and aluminum-stainless steel clads is challenging, and explosive welding is one of the most suitable processes to achieve them. The present work aims to investigate the coupled effect of two strategies for optimizing the production of these clads by explosive welding: the use of a low-density interlayer and the use of a low-density and low-detonation velocity explosive mixture. A broad range of techniques was used to characterize the microstructural and the mechanical properties of the welds, specifically, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, microhardness and tensile-shear testing with digital image correlation analysis. Although aluminum-carbon steel and aluminum-stainless steel have different weldabilities, clads with sound microstructure and good mechanical behavior were achieved for both combinations. These results were associated with the low values of collision point and impact velocities provided by the tested explosive mixture, which made the weldability difference between these combinations less significant. The successful testing of this explosive mixture indicates that it is suitable to be used for welding very thin flyers and/or dissimilar materials that easily form intermetallic phases.

scholarly journals Morphological and crystallographic anisotropy of severely deformed commercially pure aluminium by three-dimensional electron backscatter diffraction

2017 ◽  
Vol 50 (5) ◽  
pp. 1512-1523 ◽  
Author(s):  
Soroosh Naghdy ◽  
Hadi Pirgazi ◽  
Patricia Verleysen ◽  
Roumen Petrov ◽  
Leo Kestens
Keyword(s):  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Lattice Rotation ◽  
Fragmentation Pattern ◽  
Pure Aluminium ◽  
Local Texture ◽  
Crystallographic Anisotropy ◽  
Commercially Pure ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The aim of this paper is to examine the morphological and crystallographic anisotropy that develops during high-pressure torsion (HPT) processing. Commercially pure aluminium was subjected to monotonic HPT deformation at room temperature. The microstructure and texture were studied by large-area electron backscatter diffraction (EBSD) scans. Three-dimensional EBSD scans served to scrutinize the morphological anisotropy and local texture. It was observed that two distinct stages of grain fragmentation and saturation occur during processing. Grains exhibited an ellipsoidal shape rather than an equi-axed one. The major axes of the ellipsoids showed a favorable orientation at the steady-state stage: an almost 20° inclination towards the shear direction. The global texture was characterized by typical shear components of face-centered cubic metals at both stages. However, the local texture revealed a preferential fragmentation pattern in the first stage: orientations in the vicinity of ideal fibers became less heavily fragmented while non-ideal orientations broke up more severely. This phenomenon was linked with the lattice rotation required to bring an initial orientation close to a stable one. Although the texture weakened considerably in the fragmentation stage, the texture index did not further decrease in the saturation stage. Saturation of texture, grain refinement and formation of microstructure are discussed in the light of different microstructural coarsening mechanisms.

scholarly journals Deformation compatibility in a single crystalline Ni superalloy

2016 ◽  
Vol 472 (2185) ◽  
pp. 20150690 ◽  
Author(s):  
Jun Jiang ◽  
Tiantian Zhang ◽  
Fionn P. E. Dunne ◽  
T. Ben Britton
Keyword(s):  
Electron Backscatter Diffraction ◽  
Deformation Gradient ◽  
Advanced Characterization ◽  
Image Correlation ◽  
Polycrystalline Materials ◽  
High Angular Resolution ◽  
Resolution Electron ◽  
Backscatter Diffraction ◽  
Deformation Gradients

Deformation in materials is often complex and requires rigorous understanding to predict engineering component lifetime. Experimental understanding of deformation requires utilization of advanced characterization techniques, such as high spatial resolution digital image correlation (HR-DIC) and high angular resolution electron backscatter diffraction (HR-EBSD), combined with clear interpretation of their results to understand how a material has deformed. In this study, we use HR-DIC and HR-EBSD to explore the mechanical behaviour of a single-crystal nickel alloy and to highlight opportunities to understand the complete deformations state in materials. Coupling of HR-DIC and HR-EBSD enables us to precisely focus on the extent which we can access the deformation gradient, F , in its entirety and uncouple contributions from elastic deformation gradients, slip and rigid body rotations. Our results show a clear demonstration of the capabilities of these techniques, found within our experimental toolbox, to underpin fundamental mechanistic studies of deformation in polycrystalline materials and the role of microstructure.

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