International Tables for Crystallography Volume C: Mathematical, physical and chemical tables, 2022
This chapter provides an overview of the electron backscatter diffraction (EBSD) modality which, ... more This chapter provides an overview of the electron backscatter diffraction (EBSD) modality which, over the past thirty years, has become a core microstructure characterization technique in both the materials and geological fields. EBSD typically produces 2D maps (or 3D volumes in the case of serial sectioning) of the orientations of the constituent crystallites of a sample with respect to an external reference frame. The chapter starts by describing the experimental geometry of the sample and detector inside the chamber of a scanning electron microscope (SEM). This is followed by a review of the kinematical and dynamical theories of electron scattering which, along with the detector geometry, can be used to predict EBSD patterns, including the diffuse background intensity. Since EBSD produces orientations, several commonly used orientation representations and parametrizations are reviewed before explaining how the crystal orientation is extracted from the experimental patterns, using either Hough-transform-based feature extraction, or the whole-pattern-matching approaches known as dictionary indexing and spherical indexing. To obtain accurate results it is crucial that the sample surface be properly prepared and a number of standard techniques for obtaining an optimal sample surface finish are described. Commercial and open-source software solutions for data analysis are described as well as a number of commonly used data formats. The chapter concludes with several examples of applications taken from both the materials and geological literature, and brief ruminations on the future of the EBSD characterization technique.
In situ scanning electron microscopy was performed during elevated-temperature (ഛ760°C) tensile-c... more In situ scanning electron microscopy was performed during elevated-temperature (ഛ760°C) tensile-creep deformation of a face-centered-cubic cobalt-based Udimet 188 alloy to characterize the deformation evolution and, in particular, the grain boundary-cracking evolution. In situ electron backscatter diffraction observations combined with in situ secondary electron imaging indicated that general high-angle grain boundaries were more susceptible to cracking than low-angle grain boundaries and coincident site-lattice boundaries. The extent of general high-angle grain-boundary cracking increased with increasing creep time. Grain-boundary cracking was also observed throughout subsurface locations as observed for postdeformed samples. The electron backscattered diffraction orientation mapping performed during in situ tensile-creep deformation proved to be a powerful means for characterizing the surface deformation evolution and in particular for quantifying the types of grain boundaries that preferentially cracked.
Metallurgical and Materials Transactions, Jul 14, 2007
Shortly after the initial development of an automated technique for measuring individual crystall... more Shortly after the initial development of an automated technique for measuring individual crystallographic orientations using electron backscatter diffraction (EBSD), several studies were undertaken to estimate the number of single orientation measurements necessary to achieve the statistics of more conventional texture measurement techniques such as pole figure measurement using X-ray diffraction. Since those early studies, the speed of modern EBSD systems
A magnesium vanadate spinel crystal, ideally MgV 2 O 4 , synthesized at 1 bar, 1200 °C and equili... more A magnesium vanadate spinel crystal, ideally MgV 2 O 4 , synthesized at 1 bar, 1200 °C and equilibrated under FMQ + 1.3 log f O 2 condition, was investigated using single-crystal X-ray diffraction, electron microprobe, and electron backscatter diffraction (EBSD). The initial X-ray structure reÞ nements gave tetrahedral and octahedral site occupancies of T (Mg 0.966 ■ ■ 0.034) and M (V 3+ 0.711 V 4+ 0.109 Mg 0.180), respectively, along with the presence of 0.053 apfu Mg at an interstitial octahedral site (16c). Back-scattered electron (BSE) images and electron microprobe analyses revealed the existence of an Mg-rich phase in the spinel matrix, which was too small (≤3 μm) for an accurate chemical determination. The EBSD analysis combined with X-ray energy dispersive spectroscopy (XEDS) suggested that the Mg-rich inclusions are periclase oriented coherently with the spinel matrix. The Þ nal structure reÞ nements were optimized by subtracting the X-ray intensity contributions (~9%) of periclase reß ections, which eliminated the interstitial Mg, yielding a structural formula for spinel T Mg M (V 3+ 1.368 V 4+ 0.316 Mg 0.316)O 4. This study provides insight into possible origins of reÞ ned interstitial cations reported in the literature for spinel, and points to the difÞ culty of using only X-ray diffraction data to distinguish a spinel with interstitial cations from one with coherently oriented MgO inclusions.
... 189-94 (1988). 2 SI Wright and BL Adams, An Evaluation of the Single Orientation Method for T... more ... 189-94 (1988). 2 SI Wright and BL Adams, An Evaluation of the Single Orientation Method for Texture Determination in Materials of Moderate Texture Strength, Textures and Microstructures, ... Page 8. A Comparison of Texture Measurements via EBSD and X-Ray ... Mathematical ...
Electron Backscatter Diffraction (EBSD) has shown great utility in characterizing the aspects of ... more Electron Backscatter Diffraction (EBSD) has shown great utility in characterizing the aspects of microstructure related to crystallographic orientation. Such information is critical to understanding deformation in crystalline materials as well as the impact of deformation induced structural variations on recrystallization. Small angle rotations induced by the production of dislocations and their movement through the structure can be well captured by EBSD. Geometrically Necessary Dislocations (GND) can be derived from the measurement of these local variations in orientation. However, these local orientation variations are often right at the limit of angular precision that can be achieved by EBSD. Various post-processing tools have been developed to improve the angular precision. However, this is generally achieved through point-to-point smoothing of the orientation data within the measurement grid. The impact of such various filtering method are explored in terms of their impact on GND calculations. A new post processing approach which improves the EBSD indexing rate will also be presented along with results on its influence on local orientation variations. Fortunately, the general conclusion drawn from the reduction results is that these approaches generally improve the overall GND measurements.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-26/04/12,18:18:57) ... Textures of Materials - ICOTOM 13 10.4028/www.scientific.net/MSF.408-412 ... Effects of Local Texture and Grain Structure on the Sputtering Performance of
Abstract. Several recent investigations on the evolution of local orientation gradients in indivi... more Abstract. Several recent investigations on the evolution of local orientation gradients in individual grains during mechanical deformation have been published. Some authors have observed that the character of the local orientation gradients is correlated with the parent texture component. Most of these studies of substructure evolution within deformed grains have been performed in the transmission electron microscope and are thus restricted in their statistical scope. Using electron backscatter diffraction (EBSD) in the SEM, it is possible to ...
Electron backscatter diffraction (EBSD) has become a common technique for measuring crystallograp... more Electron backscatter diffraction (EBSD) has become a common technique for measuring crystallographic orientations at spatial resolutions on the order of tens of nanometers and at angular resolutions <0.1°. In a recent search of EBSD papers using Google Scholar™, 60% were found to address some aspect of deformation. Generally, deformation manifests itself in EBSD measurements by small local misorientations. An increase in the local misorientation is often observed near grain boundaries in deformed microstructures. This may be indicative of dislocation pile-up at the boundaries but could also be due to a loss of orientation precision in the EBSD measurements. When the electron beam is positioned at or near a grain boundary, the diffraction volume contains the crystal lattices from the two grains separated by the boundary. Thus, the resulting pattern will contain contributions from both lattices. Such mixed patterns can pose some challenge to the EBSD pattern band detection and indexing algorithms. Through analysis of experimental local misorientation data and simulated pattern mixing, this work shows that some of the rise in local misorientation is an artifact due to the mixed patterns at the boundary but that the rise due to physical phenomena is also observed.
SummaryElectron backscatter diffraction (EBSD) and orientation imaging microscopy have become est... more SummaryElectron backscatter diffraction (EBSD) and orientation imaging microscopy have become established techniques for analysing the crystallographic microstructure of single and multiphase materials. In certain instances, however, it can be difficult and/or time intensive to differentiate phases within a material by crystallography alone. Traditionally a list of candidate phases is specified prior to data collection. The crystallographic information extracted from the diffraction patterns is then compared with the crystallographic information from these candidate phases, and a best‐fit match is determined. Problems may arise when two phases have similar crystal structures. The phase differentiation process can be improved by collecting chemical information through X‐ray energy‐dispersive spectroscopy (XEDS) simultaneously with the crystallographic information through EBSD and then using the chemical information to pre‐filter the crystallographic phase candidates. This technique improves both the overall speed of the data collection and the accuracy of the final characterization. Examples of this process and the limitations involved will be presented and discussed.
International Tables for Crystallography Volume C: Mathematical, physical and chemical tables, 2022
This chapter provides an overview of the electron backscatter diffraction (EBSD) modality which, ... more This chapter provides an overview of the electron backscatter diffraction (EBSD) modality which, over the past thirty years, has become a core microstructure characterization technique in both the materials and geological fields. EBSD typically produces 2D maps (or 3D volumes in the case of serial sectioning) of the orientations of the constituent crystallites of a sample with respect to an external reference frame. The chapter starts by describing the experimental geometry of the sample and detector inside the chamber of a scanning electron microscope (SEM). This is followed by a review of the kinematical and dynamical theories of electron scattering which, along with the detector geometry, can be used to predict EBSD patterns, including the diffuse background intensity. Since EBSD produces orientations, several commonly used orientation representations and parametrizations are reviewed before explaining how the crystal orientation is extracted from the experimental patterns, using either Hough-transform-based feature extraction, or the whole-pattern-matching approaches known as dictionary indexing and spherical indexing. To obtain accurate results it is crucial that the sample surface be properly prepared and a number of standard techniques for obtaining an optimal sample surface finish are described. Commercial and open-source software solutions for data analysis are described as well as a number of commonly used data formats. The chapter concludes with several examples of applications taken from both the materials and geological literature, and brief ruminations on the future of the EBSD characterization technique.
In situ scanning electron microscopy was performed during elevated-temperature (ഛ760°C) tensile-c... more In situ scanning electron microscopy was performed during elevated-temperature (ഛ760°C) tensile-creep deformation of a face-centered-cubic cobalt-based Udimet 188 alloy to characterize the deformation evolution and, in particular, the grain boundary-cracking evolution. In situ electron backscatter diffraction observations combined with in situ secondary electron imaging indicated that general high-angle grain boundaries were more susceptible to cracking than low-angle grain boundaries and coincident site-lattice boundaries. The extent of general high-angle grain-boundary cracking increased with increasing creep time. Grain-boundary cracking was also observed throughout subsurface locations as observed for postdeformed samples. The electron backscattered diffraction orientation mapping performed during in situ tensile-creep deformation proved to be a powerful means for characterizing the surface deformation evolution and in particular for quantifying the types of grain boundaries that preferentially cracked.
Metallurgical and Materials Transactions, Jul 14, 2007
Shortly after the initial development of an automated technique for measuring individual crystall... more Shortly after the initial development of an automated technique for measuring individual crystallographic orientations using electron backscatter diffraction (EBSD), several studies were undertaken to estimate the number of single orientation measurements necessary to achieve the statistics of more conventional texture measurement techniques such as pole figure measurement using X-ray diffraction. Since those early studies, the speed of modern EBSD systems
A magnesium vanadate spinel crystal, ideally MgV 2 O 4 , synthesized at 1 bar, 1200 °C and equili... more A magnesium vanadate spinel crystal, ideally MgV 2 O 4 , synthesized at 1 bar, 1200 °C and equilibrated under FMQ + 1.3 log f O 2 condition, was investigated using single-crystal X-ray diffraction, electron microprobe, and electron backscatter diffraction (EBSD). The initial X-ray structure reÞ nements gave tetrahedral and octahedral site occupancies of T (Mg 0.966 ■ ■ 0.034) and M (V 3+ 0.711 V 4+ 0.109 Mg 0.180), respectively, along with the presence of 0.053 apfu Mg at an interstitial octahedral site (16c). Back-scattered electron (BSE) images and electron microprobe analyses revealed the existence of an Mg-rich phase in the spinel matrix, which was too small (≤3 μm) for an accurate chemical determination. The EBSD analysis combined with X-ray energy dispersive spectroscopy (XEDS) suggested that the Mg-rich inclusions are periclase oriented coherently with the spinel matrix. The Þ nal structure reÞ nements were optimized by subtracting the X-ray intensity contributions (~9%) of periclase reß ections, which eliminated the interstitial Mg, yielding a structural formula for spinel T Mg M (V 3+ 1.368 V 4+ 0.316 Mg 0.316)O 4. This study provides insight into possible origins of reÞ ned interstitial cations reported in the literature for spinel, and points to the difÞ culty of using only X-ray diffraction data to distinguish a spinel with interstitial cations from one with coherently oriented MgO inclusions.
... 189-94 (1988). 2 SI Wright and BL Adams, An Evaluation of the Single Orientation Method for T... more ... 189-94 (1988). 2 SI Wright and BL Adams, An Evaluation of the Single Orientation Method for Texture Determination in Materials of Moderate Texture Strength, Textures and Microstructures, ... Page 8. A Comparison of Texture Measurements via EBSD and X-Ray ... Mathematical ...
Electron Backscatter Diffraction (EBSD) has shown great utility in characterizing the aspects of ... more Electron Backscatter Diffraction (EBSD) has shown great utility in characterizing the aspects of microstructure related to crystallographic orientation. Such information is critical to understanding deformation in crystalline materials as well as the impact of deformation induced structural variations on recrystallization. Small angle rotations induced by the production of dislocations and their movement through the structure can be well captured by EBSD. Geometrically Necessary Dislocations (GND) can be derived from the measurement of these local variations in orientation. However, these local orientation variations are often right at the limit of angular precision that can be achieved by EBSD. Various post-processing tools have been developed to improve the angular precision. However, this is generally achieved through point-to-point smoothing of the orientation data within the measurement grid. The impact of such various filtering method are explored in terms of their impact on GND calculations. A new post processing approach which improves the EBSD indexing rate will also be presented along with results on its influence on local orientation variations. Fortunately, the general conclusion drawn from the reduction results is that these approaches generally improve the overall GND measurements.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.16-26/04/12,18:18:57) ... Textures of Materials - ICOTOM 13 10.4028/www.scientific.net/MSF.408-412 ... Effects of Local Texture and Grain Structure on the Sputtering Performance of
Abstract. Several recent investigations on the evolution of local orientation gradients in indivi... more Abstract. Several recent investigations on the evolution of local orientation gradients in individual grains during mechanical deformation have been published. Some authors have observed that the character of the local orientation gradients is correlated with the parent texture component. Most of these studies of substructure evolution within deformed grains have been performed in the transmission electron microscope and are thus restricted in their statistical scope. Using electron backscatter diffraction (EBSD) in the SEM, it is possible to ...
Electron backscatter diffraction (EBSD) has become a common technique for measuring crystallograp... more Electron backscatter diffraction (EBSD) has become a common technique for measuring crystallographic orientations at spatial resolutions on the order of tens of nanometers and at angular resolutions <0.1°. In a recent search of EBSD papers using Google Scholar™, 60% were found to address some aspect of deformation. Generally, deformation manifests itself in EBSD measurements by small local misorientations. An increase in the local misorientation is often observed near grain boundaries in deformed microstructures. This may be indicative of dislocation pile-up at the boundaries but could also be due to a loss of orientation precision in the EBSD measurements. When the electron beam is positioned at or near a grain boundary, the diffraction volume contains the crystal lattices from the two grains separated by the boundary. Thus, the resulting pattern will contain contributions from both lattices. Such mixed patterns can pose some challenge to the EBSD pattern band detection and indexing algorithms. Through analysis of experimental local misorientation data and simulated pattern mixing, this work shows that some of the rise in local misorientation is an artifact due to the mixed patterns at the boundary but that the rise due to physical phenomena is also observed.
SummaryElectron backscatter diffraction (EBSD) and orientation imaging microscopy have become est... more SummaryElectron backscatter diffraction (EBSD) and orientation imaging microscopy have become established techniques for analysing the crystallographic microstructure of single and multiphase materials. In certain instances, however, it can be difficult and/or time intensive to differentiate phases within a material by crystallography alone. Traditionally a list of candidate phases is specified prior to data collection. The crystallographic information extracted from the diffraction patterns is then compared with the crystallographic information from these candidate phases, and a best‐fit match is determined. Problems may arise when two phases have similar crystal structures. The phase differentiation process can be improved by collecting chemical information through X‐ray energy‐dispersive spectroscopy (XEDS) simultaneously with the crystallographic information through EBSD and then using the chemical information to pre‐filter the crystallographic phase candidates. This technique improves both the overall speed of the data collection and the accuracy of the final characterization. Examples of this process and the limitations involved will be presented and discussed.
Uploads
Papers by Stuart Wright