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November 2017 - present
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- Professor
Description
- Crystallography for EBSD, EBSD: Fundamentals, measurement setup, and applications
July 2011 - present
July 2008 - June 2011
Publications
Publications (243)
For the description of (single) crystal orientations, e.g. as measured by electron backscatter diffraction (EBSD) & X-ray diffraction, Euler angles are still generally used to import and export data. However, because of the lack of standard definitions for the unit cell reference settings and specimen axes, several transformation descriptions exist...
The main component of this program is a simultaneous
representation of the unit cell and the calculated powder
pattern. It allows the manipulation of the crystal structure by
moving selected atoms of the asymmetric unit. The resulting
powder pattern can be directly compared to experimental data
in order to obtain reliable starting values for furthe...
The high sample tilt angle commonly necessary for an orientation determination by EBSD (electron back-scatter diffraction) is responsible for some simple geometrically caused, but nevertheless essential, image distortions. First of all, the influence of the tilt correction and also the trapezium distortion which appears at low magnifications will b...
![Gnomonic projection of lattice directions [uvw] in a projection plane...](profile/Gert-Nolze/publication/307415105/figure/fig1/AS:11431281286781175@1730149833589/Gnomonic-projection-of-lattice-directions-uvw-in-a-projection-plane-parallel-to-010_Q320.jpg)
![Indexing of [uvw] for an assumed projection plane parallel to (010)....](profile/Gert-Nolze/publication/307415105/figure/fig3/AS:11431281286790574@1730149834798/Indexing-of-uvw-for-an-assumed-projection-plane-parallel-to-010-The-pattern-centre_Q320.jpg)
![The intersection of four coplanar lattice directions – here [001],...](profile/Gert-Nolze/publication/307415105/figure/fig4/AS:11431281286848980@1730149835214/The-intersection-of-four-coplanar-lattice-directions-here-001-114-112-and-111_Q320.jpg)
Kikuchi diffraction patterns can provide fundamental information about the lattice metric of a crystalline phase. In order to improve the possible precision and accuracy of lattice parameter determination from the features observed in Kikuchi patterns, some useful fundamental relationships of geometric crystallography are reviewed, which hold true...
The design of novel materials hinges on the understanding of structure-property relationships. However, our capability to synthesize a large number of materials has outpaced the ability and speed needed to characterize them. While the overall chemical constituents can be readily known during synthesis, the structural evolution and characterization...
Electron backscatter diffraction (EBSD) patterns can exhibit Kikuchi bands with inverted contrast due to anomalous absorption. This can be observed, for example, on samples with nanoscale topography, in case of a low tilt backscattering geometry, or for transmission Kikuchi diffraction (TKD) on thicker samples. Three examples are discussed where co...
To visualize the varying tetragonal distortions in high carbon martensitic steels by EBSD, two different approaches have been applied on backscattered Kikuchi diffraction (BKD) patterns. A band-edge refinement technique called Refined Accuracy (RA) (Oxford Instruments) is compared with a technique called Pattern Matching (PM), which optimizes the f...
A band width determination using the first derivative of the band profile systematically underestimates the true Bragg angle. Corrections are proposed to compensate for the resulting offset Δa/a of the mean lattice parameters derived from as many Kikuchi band widths as possible. For dynamically simulated Kikuchi patterns, Δa/a can reach up to 8% fo...
A pseudosymmetric description of the crystal lattice derived from a single wide-angle Kikuchi pattern can have several causes. The small size (<15%) of the sector covered by an electron backscatter diffraction pattern, the limited precision of the projection centre position and the Kikuchi band definition are crucial. Inherent pseudosymmetries of t...
The derivation of a crystal structure and its phase-specific parameters from a single wide-angle backscattered Kikuchi diffraction pattern requires reliable extraction of the Bragg angles. By means of the first derivative of the lattice profile, an attempt is made to determine fully automatically and reproducibly the band widths in simulated Kikuch...
This paper presents the results of a study of the morphology and structure at the weld interface in a brass–Invar bimetal, which belongs to the class of so-called thermostatic bimetals, or thermobimetals. The structure of the brass–Invar weld interface was analyzed using optical microscopy and scanning electron microscopy (SEM), with the use of ene...
The morphology of pores partially shrunk during a half-hour HIP at temperature of 1288 °C and pressure of 103 MPa has been investigated in nickel-based superalloy CMSX-4. The investigation resulted in the following findings: surrounding the shrinking pores by a γ′-shell (Ni3Al), faceting of the pores surface by {023} and {011} planes, and formation...
Inconel 718 is a precipitation strengthened, nickel-based super alloy of interest for the Additive Manufacturing (AM) of low volume, complex parts to reduce production time and cost compared to conventional subtractive processes. The AM process involves repeated rapid melting, solidification and reheating, which exposes the material to non-equilibr...
Electron backscatter diffraction and energy-dispersive X-ray spectrometry were used to investigate the intermixed interface produced during laser cladding of a Co – Cr –Mo alloy on a steel substrate. A multi-component system and rapid solidification conditions together lead to a complex microstructure at the interface. The solidification of the cla...
A Co – Cr –Mo laser cladding applied on railway wheels is characterised by a combination of EBSD and EDX. A complete pass of the cladding is investigated to achieve a better understanding of the microstructure evolution during laser cladding. A microstructure with columnar grains extending over the whole thickness of the cladding is observed. The g...
Bravais lattice type and lattice parameter determination using a single EBSD pattern by CALM (crystallographic analysis of the lattice metric). The presentation explains fundamentals, describes challenges and presents possible or necessary corrections. To exclude experimental uncertainties like the projection center position, the wave length, the r...
Signal optimization for transmission Kikuchi diffraction (TKD) measurements in the scanning electron microscope is investigated by a comparison of different sample holder designs. An optimized design is presented, which uses a metal shield to efficiently trap the electron beam after transmission through the sample. For comparison, a second holder c...
We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal, and (b) diffraction effect...
A new software is presented for the determination of crystal lattice parameters from the positions and widths of Kikuchi bands in a diffraction pattern. Starting with a single wide-angle Kikuchi pattern of arbitrary resolution and unknown phase, the traces of all visibly diffracting lattice planes are manually derived from four initial Kikuchi band...
PC was calibrated on retained austenite,
experimental martensite patterns were compared to BCC and BCT (c/a=1.06) dynamically simulated patterns.
Use PageUp/PageDown for best result.
The locally varying tetragonality in martensite grains of a high‑carbon steel (1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD) with a spatial resolution in the order of 100 nm. Compared to spatially integrating X-ray diffraction, which yielded an average tetragonality of c/a = 1.05, the EBSD measurements in the scanning...
The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufac...
Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel‐base superalloy CMSX‐10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening γ′‐phase is partially dissolved. The porosity is studied by X‐ray sub‐μ tomography with a spatial resolution of ab...
New software and algorithms are presented for the accurate measurement of crystal
lattice parameters based on the positions and widths of Kikuchi bands in a
diffraction pattern. Starting with a single wide-angle Kikuchi pattern of arbitrary
resolution and unknown phase, the traces of all visibly diffracting lattice planes
are manually derived from...
CALM is software for determining the Bravais lattice type and the resulting lattice parameters from a single Kikuchi pattern. It requires the definition of 4 bands and a single bandwidth from which all other band positions as well as bandwidths are derived. For band detection, it uses the Funk transform, which allows detection of twice as many band...
The locally varying tetragonality in martensite grains of a high-carbon steel (1.2 mass percent C) was resolved by electron backscatter diffraction (EBSD) with a spatial resolution in the order of 100nm. Compared to spatially integrating X-ray diffraction, which yielded an average tetragonality of c/a=1.05, the EBSD measurements in the scanning ele...
The effect of two types of scanning strategies on the grain structure and build-up of Residual Stress (RS) has been investigated in an as-built IN718 alloy produced by Laser Powder Bed Fusion (LPBF). The RS state has been investigated by X-ray diffraction techniques. The microstructural characterization was performed principally by Electron Backsca...
An extensive set of information about the diffracting volume is carried by EBSD patterns: the crystal lattice, the reciprocal lattice, the crystal structure, the crystal symmetry, the mean periodic number of the diffracting phase, the source point from where it has been projected (projection centre), the crystal orientation, the sample topography (...
Orientation mapping of quasicrystalline materials is demonstrated using crystalline approximant structures in the technique of electron backscatter diffraction (EBSD). The approximant-based orientations are symmetrised according to the rotational point group of the quasicrystal, including the visualization of orientation maps using proper colour ke...
For the precise determination of orientations in polycrystalline materials, electron backscatter diffraction (EBSD) requires a consistent calibration of the diffraction geometry in the scanning electron microscope (SEM). In the present paper, the variation of the projection center for the Kikuchi diffraction patterns which are measured by EBSD is c...
The early stages of corrosion of Fe-Cr-model alloys (2 and 9 % Cr) were investigated after exposure at 650 °C in 0.5% SO2 containing gas by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The impact of the grain orientation of the base alloy on the orientation relations of the corrosion products is presented. A...
A historical tool for crystallographic analysis is provided by the Hilton net, which can be used for manually surveying the crystal lattice as it is manifested by the Kikuchi bands in a gnomonic projection. For a quantitative analysis using the Hilton net, the projection centre as the relative position of the signal source with respect to the detec...
Orientation determination does not necessarily require complete knowledge of the local atomic arrangement in a crystalline phase. We present a method for microstructural phase discrimination and orientation analysis of phases for which there is only limited crystallographic information available. In this method, experimental Kikuchi diffraction pat...
An extensive set of information about the diffracting volume is carried by EBSD patterns: the crystal lattice, the reciprocal lattice, the crystal structure, the crystal symmetry, the mean periodic number of the diffracting phase, the source point from where it has been projected (projection center), the crystal orientation, the sample topography (...
Roaldite – Fe4N – has been identified in the São Julião de Moreira iron meteorite using electron backscatter diffraction (EBSD) and simultaneously acquired energy-dispersive x-ray spectroscopy (EDS). Mean-periodic-number images derived from raw EBSD patterns confirm this phase by an even higher spatial resolution compared to EDS.
Roaldite appears i...
As humanity contemplates manned missions to Mars, strategies need to be developed for the design and operation of hospitable environments to safely work in space for years. The supply of spare parts for repair and replacement of lost equipment will be one key need, but in‐space manufacturing remains the only option for a timely supply. With high fl...
Gold and platinum-group-metals (PGM) are cycled through Earth’s environments by interwoven geological, physical, chemical and biological processes leading to the trans/neoformation of metallic particles in placers. The placer deposit at Corrego Bom Successo (CBS, Brazil) is one of the few localities worldwide containing secondary gold- and PGM-part...
Orientation determination does not necessarily require complete knowledge of the local atomic arrangement in a material. We present a method for microstructural phase discrimination and orientation analysis of phases for which there is only limited information available. In this method, experimental Kikuchi diffraction patterns are utilized to gene...
Additive manufacturing processes (AM) offer different advantages compared to conventional manufacturing processes. In this work the microstructure of austenitic steel 316L, manufactured with Selective Laser Melting (SLM), and the powder, used for the process, were investigated.
Additive manufacturing (AM) offers diverse advantages compared to conventional manufacturing. In this work the microstructure of austenitic steel 316L, manufactured with Selective Laser Melting (SLM), was analyzed and compared to microstructure of 316L hot rolled material. Methods used for analysis are microprobe, optical microscopy and electron ba...
Electron backscatter diffraction (EBSD) is a technique to obtain microcrystallographic information from materials by collecting large-angle Kikuchi patterns in the scanning electron microscope (SEM). An important fundamental question concerns the scattering-angle dependent electron energy distribution, which is relevant for the formation of the Kik...
We describe a lattice-based crystallographic approximation for the analysis of distorted crystal structures via electron backscatter diffraction (EBSD) in the scanning electron microscope. EBSD patterns are closely linked to local lattice parameter ratios via Kikuchi bands that indicate geometrical lattice plane projections. Based on the transforma...
Electron Backscatter Diffraction (EBSD) is a technique to obtain microcrystallographic information from materials by collecting large-angle Kikuchi patterns in the scanning electron microscope (SEM). An important fundamental question concerns the scattering-angle dependent electron energy distribution which is relevant for the formation of the Kiku...
We describe a lattice-based crystallographic approximation for the analysis of distorted crystal structures via Electron Backscatter Diffraction (EBSD) in the scanning electron microscope. EBSD patterns are closely linked to local lattice parameter ratios via Kikuchi bands that indicate geometrical lattice plane projections. Based on the transforma...
The Bravais lattices and their lattice parameters are blindly determined using electron backscatter diffraction (EBSD) patterns of materials with cubic or tetragonal crystal structures. Since the geometric relationships in a single EBSD pattern are overdetermined, the relative errors of determining the lattice parameters as well as the axial ratios...
Due to their excellent combination of ductility, strength and corrosive resistance, austenitic stainless steels (ASS) are widely used in many industrial applications. Thus, these steel grades can be found as structural components in the (petro-)chemical industry, in offshore applications and more recent for storage and transport of hydrogen fuel. [...
We use pattern matching of experimental and dynamically simulated backscattered Kikuchi diffraction (BKD) patterns to increase the orientation precision of electron backscatter diffraction (EBSD) measurements. In order to quantify the improvement in orientation precision, we analyze the experimental distribution of the kernel average misorientation...
The alloying system Co-Al-W-Ta is comprehensively investigated in the vicinity of the compositional point Co-9Al-10W-2Ta, at. pct. These investigations provided a large amount of quantitative information, which can be used for alloy development, namely, the compositional dependences of the γ′-solvus, solidus, and liquidus temperatures; fraction of...
![Figure 1. Content of trace elements in the samples [ppm]. (a) S and Cu,...](publication/325744093/figure/fig1/AS:637106586128388@1528909455818/Content-of-trace-elements-in-the-samples-ppm-a-S-and-Cu-b-As-and-Pb-c-Mn-Ni_Q320.jpg)
Due to the increasing global demand for pure silver, native wire silver aggregates in very high purities are gaining more industrial attention. Up to the present, no substantial metallurgical investigation of natural wire silver exists in the accessible literature. To convey urgently needed cross-disciplinary fundamental knowledge for geoscientists...
The creep behavior of single crystals of the nickel-based superalloy CMSX-4 was investigated at 1288 °C, which is the temperature of the hot isostatic pressing treatment applied to this superalloy in the industry. It was found that at this super-solvus temperature, where no γ′-strengthening occurs, the superalloy is very soft and rapidly deforms un...
We use pattern matching of experimental and dynamically simulated backscattered Kikuchi diffraction (BKD) patterns to increase the orientation precision of electron backscatter diffraction (EBSD) measurements. In order to quantify the improvement in orientation precision, we analyze the experimental distribution of the kernel average misorientation...
Preparation artifacts are not always easy to recognize, especially if the material investigated is unknown for the operator or assumed to be heavily deformed so that an overlaid additional distortion is difficult to discriminate. A few examples for different preparation techniques and materials are shown. They shall serve as a warning for a too has...
Sampling, sample preparation and measurement area selection are very important for any interpretation of results since they are assumed to be representative. Unfortunately, the imagination that a polished surface which does not show any obvious damaging represents the real microstructure of a material is in maximum an educated guess but no proof. A...
The presented compilation of fundamental crystallographic relationships demonstrates the strong correlation between crystal and reciprocal lattice. Exemplary, they are important for a correct interpretation of electron backscatter diffraction (EBSD) patterns but also useful for any other technique based on geometric crystallography. A major benefit...
(Bio)geochemical cycling of gold (Au) has been demonstrated in present-day (semi)-arid, (sub)-tropical and temperate environment. Hereby biofilms on Au-bearing mineral- and Au-particle surfaces drive Au dispersion and reconcentration, thereby (trans)forming the particles. However, it is unknown if biogeochemical cycling of Au occurs in polar enviro...
Interdiffusion of Al, W, Ta and Co in a Co-base alloy at temperatures between 1090 and 1240 °C has been investigated. The interdiffusion coefficients were found to be close to those reported for these elements in Ni-base alloys. Combining the diffusion simulation software DICTRA with the Ni-base diffusion databases TCNi5 and MobNi3, the interdiffus...
The use of materials for tribological applications in hot steam environment becomes more important in the future. Unfortunately, experimental data recorded under hot steam conditions are scarce mainly due to suitable testing equipment. This work examines the wear behaviour of α-aluminium oxide by combining thermodynamic modelling with advanced wear...
On April 23rd 2013 at 2:07 a.m., a 1.3 kg meteorite fell in the Braunschweig suburb Melverode (52° 13′ 32.19″ N. 10° 31′ 11.60″ E). Its estimated velocity was 250 km/h and it formed an impact pit in the concrete fall site with a diameter of 7 cm and a depth of 3 cm. Radial dust striae are present around the impact pit. As a result of the impact, th...
Advanced structural characterisation techniques which are rapid to use, non-destructive and structurally definitive on the nanoscale are in demand, especially for a detailed understanding of extended-defects and their influence on the properties of materials. We have applied the electron backscatter diffraction (EBSD) technique in a scanning electr...
Deformation and structural behavior of an experimental γ'-strengthened Co-base alloy during creep at 800°C and 196 MPa has been investigated. Characteristic features of this alloy are a zero γ/γ'-lattice misfit and a fine γ/γ'-microstructure. In the initial condition, the γ'-precipitates in this alloy are small (size of about 100 nm), have polyhedr...
The effect of electrochemical charging of hydrogen on the structure of a lean duplex stainless steel LDX 2101 R (EN 1.4162, UNS S32101) was examined by both Time-of-Flight secondary ion mass spectrometry and electron backscatter diffraction. The goal is to correlate hydrogen concentration and induced structural changes. Chemical and structural char...
The presentation is part of a teaching material concentrating on very fundamental crystallography especially for EBSD. It displays the strong correlation of EBSD patterns with the crystal lattice as well as its reciprocal lattice.
Mapping Anti-phase Domains by Polarity Sensitive Orientation Imaging Using Electron Backscatter Diffraction - Volume 23 Issue S1 - G. Naresh-Kumar, S. Vespucci, A. Vilalta-Clemente, H. Jussila, A. Winkelmann, G. Nolze, S. Nagarajan, A. J. Wilkinson, C. Trager-Cowan
For explanation of the band distribution in EBSD patterns it is beneficial to have some model. The shown code simple generates the high-resolved distribution around a [001] pole of magnetite in order to display the intensity distribution and the geometrical relationships, how band widths are related to each other. Using IguanaTeX in PowerPoint this...
Comparison of raw orientation data and orientation data after pattern matching refinement. The zip file contains ctf files which should be possible to import in your EBSD system.
The material is a martensitic steel after LCF loading (620°C) scanned with 120nm step size in a squared raster. The dwell time was 15ms.
Sometimes the sketch of a crystal lattice in 3D would be perfect, e.g. in order to show lattice directions for different crystal metric. This code enables a simple drawing of a lattice using integers as lattice parameters and shear components of a matrix to describe an oblique lattice. TIKZ can be used for PowerPoint presentations as well if Iguana...
This image is for cross looking, i.e. you need to squint. More relaxing is the parallel view where you need to exchange both images, i.e. left to right and right to left.
The increase of orientation precision and also accuracy is a an important factor for a better understanding of deformed or undeformed materials. A simple increase of pattern resolution is certainly a possible way but not very practical since it also means a higher acquisition time as well as a possibly higher image drift. Therefore, the talk repres...
Der Mineralbstand einer BIF-Probe, bestehend aus Silizium- und Eisenoxiden, wurde mittels EBSD und EDS bestimmt.
Pseudosymmetry is an important issue for EBSD users since not only the crystallographic pseudosymmetry is covered by this term but any reason which finally results in a misinterpation of EBSD patterns. Thus, software related limitations or experimental reasons are usually included as well and have to be critically discussed. However, this talk main...
The work focuses on the potential of structural and chemical examinations by scanning electron microscopy based methods for archaeometric studies on ceramics. Achieved by a single preparation technique (polished block sections), the feasibility and benefits of electron backscatter diffraction are demonstrated as case studies using polychrome exampl...
The small code generates a sketch of a SAED pattern (TEM) displaying the reflector distribution of hk0 for a cubic [001] projection. The absent reflections match to the conditions for magnetite. Any [001] pattern can be generated by editing the respective hk0 inclusive their diameter which display the reflector intensity.
The code enables the drawing of Wulffs net in LaTeX documents or PowerPoint presentation using IguanaTex as Add-In.
We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes...
An EBSD pattern represents the gnomonic projection of the backscattered electron signal emitted from a point source. If the emitting volume is monocrystalline the background-corrected signal reflects an intensity distribution which is dominated by band-like accumulations. It is well-accepted that the “centres” of these band-like structures indicate...
The information content of EBSD patterns is briefly explained, and rules and recommendations for phase identification using EBSD and EDS are given.
During the processing of superconducting Nb3Sn wire, several intermediate intermetallic phases including a previously encountered Cu-Nb-Sn phase show up. The yet unknown crystal structure of this phase is now identified by a combination of different experimental techniques and database search to be of the hexagonal NiMg2 type with a proposed com-po...
Transformation of fcc to bcc with a simultaneous variation of the projection center in order to show that there is a strong relationship. The idea was a) to show that any EBSD pattern of fcc can be indexed by bcc and vice versa. The trick is the projection center which is of course wrong for the wrong phase. Moreover, it should demonstrate b) that...
Questions
Questions (116)
I know that this is a very difficult question, as the areas of application can vary greatly. However, if you want to operate low as well as high resolution (from a few millimeters to nanometers), need the highest possible beam current for analysis, but also very flexible with regard to large samples or non-conductive samples (low vacuum device), a whole series of devices or manufacturers fall out, as far as I know. If you don't want to constantly change pressure stage apertures, the only manufacturer I can think of at the moment is Zeiss.
Ladies and gentlemen, I have a favor to ask of you. If you've collected beautiful and back-corrected EBSD patterns of preferably non-cubic phases... could you send them to me along with the information about the projection center (pattern center + detector distance)? If this information is not available, it doesn't matter... It would also be nice to know the diffracting phase, but even that is not necessary if the pattern looks good. The resolution should not be lower than 400x300 pixels. In any case, it doesn't necessarily have to be high resolution patterns. The image format is irrelevant. I want use the patterns for tests regarding crystal lattice description (approximate lattice parameters and crystal symmetry). If I should use the patterns later in publications you can be sure that I will refer to you. Thanks in advance!
Aside form the software delivered together with an EBSD-detector like OIM, Aztec, CrystAlign and Quasor, alternative software packages exist like ATEX, MTEX, DREAM.3D. Which other software is (more or less) system-independent and can be used as well for EBSD data analyses?
