Showing papers on "Electron backscatter diffraction published in 2002"
TL;DR: In this article, the negative slope of yield stress versus d−1/2 in ECAPed AZ61 alloys can be explained by the gradual transition of the texture during repetitive equal channel angular pressing (ECAP) to control the grain size.
328 citations
TL;DR: In this article, the formation of low-energy grain boundaries through this mechanism and its effect on boundary network topology is discussed within the context of grain boundary engineering and linked to known microstructural evolution mechanisms.
232 citations
TL;DR: In this paper, the microstructures of two contrasting garnet grains are mapped using automated electron backscatter diffraction, showing that misorientation angles measured across orientation domain boundaries are significantly lower than those measured between random pairs of orientation domains.
203 citations
TL;DR: In this article, the conditions under which micron-scale grain structures can be developed in two Al-3%Mg alloys by a process of continuous recrystallization, during rolling and plane strain compression to large strains, have been investigated using high resolution electron backscatter diffraction (EBSD).
195 citations
TL;DR: In this article, the evolution of microstructure and crystallographic texture in low alloyed titanium sheets, initially deformed by 80% cold rolling, are investigated at different stages of the recrystallisation process.
164 citations
TL;DR: Application of the methodology to deformed zirconium suggests that the twinning planes remain coherent during deformation, and was also used to improve grain size distributions measured by OIM, which more closely match those obtained by conventional metallography.
Abstract: Automated electron backscatter diffraction or orientation imaging microscopy (OIM) provides spatially specific measurements of crystallographic orientation. These measurements are typically collected on regular grids. By inspecting the misorientation between neighbouring measurements on the grid, potential twin boundaries can be identified. If the misorientation is within some given tolerance of a specified twin misorientation, the boundary separating the two measurements may be identified as a potential twin boundary. In addition, for a coherent twin, the twinning planes must be coincident with the grain boundary plane. As OIM scans are inherently two-dimensional, the scan data provide only limited information on the boundary plane. Thus, it is not possible to ascertain definitively whether the twinning planes are coincident with the boundary plane. Nonetheless, the alignment of the surface traces of the twinning planes with the trace of the boundary provides a partial indication of coincidence. An automated approach has been developed that allows data concerning both twin criterion to be extracted from OIM scans. Application of the methodology to deformed zirconium suggests that the twinning planes remain coherent during deformation. The methodology was also used to improve grain size distributions measured by OIM. These results more closely match those obtained by conventional metallography.
141 citations
TL;DR: In this article, the microstructure and mechanical properties of LIGA-fabricated nickel (LIGA Ni), electrodeposited using Watts bath and sulfamate bath chemistries were investigated.
Abstract: Lithographic, Galvanoformung, Abformung (LIGA) component fabrication is a process in which structural material is deposited into a patterned polymethyl-methacrylate (PMMA) mold realized through deep X-ray lithography. The process permits fabrication of metal microelectrome chanical systems (MEMS) components with representative dimensions that range from a few microns to several millimeters. This investigation characterizes the microstructure and mechanical properties of LIGA-fabricated nickel (LIGA Ni), electrodeposited using Watts bath and sulfamate bath chemistries. As a prelude to studying high-temperature joining processes in LIGA Ni components, an annealing investigation was conducted on samples fabricated from both bath chemistries. Mechanical properties and microstructural analyses on as-deposited and annealed samples were conducted using a mini servohydraulic load frame and the electron backscatter diffraction (EBSD) microtexture measurement technique. The deposits were found to have fine-grain, highly textured microstructures oriented with an acicular or columnar morphology relative to the plating direction. Previously uncharacterized, anomalous, local spatial variations in the crystallographic texture of the as-deposited microstructures were identified by EBSD analyses. Microstructural evolution during annealing seemed to follow a recovery, recrystallization, rapid grain-growth microstructural-evolution mechanism in LIGA Ni deposited from the Sulfamate bath chemistry and simply a recovery and grain-growth microstructural-evolution mechanism in LIGA Ni deposited from the Watts bath chemistry. The evolution of microstructure in the annealed samples corresponded with a dramatic drop in their strength and determined the limiting diffusion-bonding temperature for LIGA Ni components.
111 citations
TL;DR: In this article, the authors investigated the role of three basic mechanisms, namely oriented nucleation, growth, and recrystallization twinning, in the initial stages of recrystization texture development in this low stacking fault energy alloy.
105 citations
31 Jan 2002-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, both electron back-scattered diffraction (EBSD) and atomic force microscopy (AFM) have been used to study surface slip features on 316L austenitic stainless steel polycrystals tested in the low cycle fatigue range.
Abstract: Electron back-scattered diffraction (EBSD) and atomic force microscopy (AFM) have been used to study surface slip features on 316L austenitic stainless steel polycrystals tested in the low cycle fatigue range. EBSD investigations allow activated slip planes to be identified for each grain and the local inclination of these slip planes to the surface to be calculated. AFM allows the height of steps induced at the surface along slip bands to be measured and the local morphology of extrusions to be characterized at a nanometer scale. In this study, both techniques are used on the same surface in order to combine crystallographic and topographic information. Based on the results, a schematic model of the slip band emergence is proposed.
104 citations
TL;DR: In this article, the effect of the local crystallographic properties on microscopic and macroscopic cracking resistance was studied in a large number of materials, including intergranular, brittle transgranular and fatigue cracking.
Abstract: Electron backscatter diffraction (EBSD) is now a well developed technique that allows for determination of 'microtexture', i.e. texture at the scale of the grain size. The effect of the local crystallographic properties on microscopic and macroscopic cracking resistance was studied in a large number of materials. Electron backscatter diffraction and EBSD related techniques provide a lot of data concerning intergranular, brittle transgranular, and fatigue cracking. In particular, they help with understanding the role of the grain boundary structure, the grain orientation and the misorientation between grains respectively. Electron backscatter diffraction characterisation of interfaces has already led to improvements of material performance in practical industrial applications, a typical example being given by grain boundary engineering. Information about the local crystallography together with a high spatial resolution encourages the application of the technique to cracking modes of other material...
101 citations
TL;DR: In this paper, the authors reviewed the use of electron backscatter Kikuchi diffraction patterns (BKDPs) in the scanning electron microscope, including point group and space group determination and strain analysis.
Abstract: The technique of electron backscatter Kikuchi diffraction patterns (BKDPs) in the scanning electron microscope is reviewed. The paper focuses mainly on the crystallographic applications of the technique, including discussions on point group and space group determination and strain analysis. Orientation microscopy is discussed but not reviewed. The geometrical configurations of BKDPs are reviewed in detail and the relationship between BKDPs and the technique of electron channelling patterns (ECPs) is explored briefly. Essential crystallography is discussed and methods of analysis of BKDPs to extract crystallographic information are analyzed in detail. Some important characteristics of diffraction contrast in BKDPs are analyzed with respect to the geometry of the technique, the dynamical theory of electron diffraction and crystallographic applications. Examples of the use of theoretical contrast in pattern interpretation are provided. Anomalous effects in BKDPs are analyzed in detail and ways of identifying anomalous contrast in practice are discussed. BKDPs included in the paper are zincblende (ZnS), silicon, germanium, GaAs, chalcopyrite (CuFeS2, TaTe4 and Er2Ge2O7.
TL;DR: In this paper, an epitaxial Cu(In, Ga)Se2 (CIGS) was grown on (110)-oriented GaAs substrates using a hybrid sputtering and evaporation process.
Abstract: Epitaxial Cu(In, Ga)Se2 (CIGS) films were grown on (110)-oriented GaAs substrates using a hybrid sputtering and evaporation process. The morphological and structural properties were determined by scanning electron microscopy, atomic force microscopy, x-ray diffraction, and electron backscatter diffraction. Pronounced faceting was observed on the surfaces of the films and Ga diffusion was observed at higher growth temperatures from the substrates into the films. The (220)/(204) surface of CIGS was found to be unstable under the growth conditions. The resulting surface consists entirely of {112} type facets with no observable (220)/(204)-oriented surfaces. The epitaxial temperature for the (220)/(204) layers is considerably lower than that on any other surface tested and is attributed to the reduced diffusion distance required for adatoms to reach growth sites. The surface is proposed to grow by rapid nucleation and gradual growth of Se terminated steps across Se terminated surface terraces. This causes the...
TL;DR: In this paper, the electron-beam welding behaviors of pure Mg and the AZ31, AZ61, and AZ91 alloys are examined in terms of fusion-zone characteristics, grain structures, texture evolution, and joint efficiency.
Abstract: The electron-beam welding (EBW) behaviors of pure Mg and the AZ31, AZ61, and AZ91 Mg alloys are examined in this study, in terms of fusion-zone characteristics, grain structures, texture evolution, and joint efficiency. With increasing A1 content, the Mg-based materials were found to be more easily fusion welded. The AZ91 alloy could be welded using a beam power of 2200 W and a weld speed of 16 mm/s, resulting in a weld depth of 29 mm with a fusion-zone aspect ratio of 8.2. The grains inside the fusion zone were nearly equiaxed in shape and ∼10 µm in size, due to the rapid cooling rate. Extended partial melting zones were observed in alloys with high solute contents, such as AZ61 and AZ91. The postweld tensile strength of the Mg alloys could recover back to ∼80 to 110 pct of the original strength. The texture in the fusion zone was traced by X-ray diffraction (XRD) and electron-backscattered diffraction (EBSD). The grain orientations inside the rapidly solidified electron-beam-welded fusion zones are still rather diversely distributed. The α
1-, α
2-, and α
3-axes of some grains tend to align at 90 or 30 deg with respect to welding direction, and the c-axis tends to align along the plate normal direction. The influence from surface tension on the weld top-surface appearance and weld depth was not pronounced for the current four Mg materials. Instead, differences in the solidus temperatures and thermal conductivity should be the primary factors.
TL;DR: In this paper, a detailed optical, electron microprobe and scanning electron microscopic study, combined with electron backscatter diffraction techniques, suggests that fragmentation of garnet took place quasi-instantaneously at very high peak stresses.
TL;DR: A focused ion beam (FIB) instrument has been used to mill surfaces in singlecrystal Si and single-crystal Cu for subsequent electron backscattering diffraction (EBSD) analysis as discussed by the authors.
Abstract: A focused ion beam (FIB) instrument has been used to mill surfaces in single-crystal Si and single-crystal Cu for subsequent electron backscattering diffraction (EBSD) analysis. The FIB cuts were performed using a 30 keV and a 5 keV Ga+ ion beam at a stage tilt of 20° to provide a readily obtainable 70° surface for direct EBSD investigation in a scanning electron microscope (SEM). The quality of the patterns is related to the amount of FIB damage induced in the Cu and Si. These or similar methods should be directly transferable to a FIB/SEM dual beam instrument equipped with an EBSD detector.
TL;DR: In this paper, a crack between two single crystals of aluminum joined by a thin ductile interlayer of tin is introduced via selective chemical etching and can be considered sharp; the material surrounding the tip is fully annealed.
TL;DR: In this article, secondary cleavage cracks in the A 508 C1.3 bainitic steel were analyzed using electron backscattering diffraction (EBSD) and scanning electron microscopy (SEM).
TL;DR: In this article, the atomic structure of carbon nanotubes is deduced from high-resolution electron microscopy and electron diffraction in transmission through a single nanotube, and the principal features of the observed micrographs are interpreted in terms of the cylindrical, chiral geometry of the atomic distribution of single-wall or multi-wall nanotsubes.
Abstract: This colloquium discusses the atomic structure of carbon nanotubes as deduced from high-resolution electron microscopy and electron diffraction in transmission through a single nanotube. The principal features of the observed micrographs are interpreted in terms of the cylindrical, chiral geometry of the atomic distribution of single-wall or multiwall nanotubes. In order to better understand the mechanism of image formation in electron diffraction, the authors propose optical simulation experiments using a laser pointer and a little ``diffraction laboratory on a slide.'' The simulations visibly reproduce all the features of the observed electron micrographs, namely, the quasihexagonal patterns of Bragg spots, the streaked nature of the spots, the doubling of the spot number induced by chirality, etc. The present colloquium should allow a general readership to appreciate the continuing efficiency and power of diffraction methods for the determination of the structure of macromolecules.
TL;DR: In this article, a quantitative study of the microstructure of nickel-based superalloy RR1000 tube structures joined by inertia welding has been performed by measuring the hardness profiles and microstructurally in terms of γ grain size, γ precipitate size and volume fraction, stored energy, and microtexture.
Abstract: This article describes a quantitative study of the microstructure of nickel-based superalloy RR1000 tube structures joined by inertia welding. One as-welded and three post weld heat-treated (PWHT) conditions have been investigated. The samples were characterized mechanically by measuring the hardness profiles and microstructurally in terms of γ grain size, γ′ precipitate size and volume fraction, stored energy, and microtexture. Electron backscatter diffraction (EBSD) was used to characterize high-angle grain boundaries (HAGB) and the variation of microtexture across the weld line. The coherent γ′ precipitates were investigated over a range of scales on etched samples in a field emission gun scanning electron microscope (FEGSEM), using carbon replicas in a transmission electron microscope (TEM) and from thin slices by means of high-energy synchrotron X-rays. Dramatic changes in the microstructure were observed within 2 mm of the weld line. In this region, the hardness profile is influenced by changes in grain size, γ′ volume fraction, γ′ particle size, and the work stored in the material. Further away, the observed hardness variation is still significant although only minor microstructural changes could be observed. In this region, the correlation of microstructure and hardness is less straightforward. Here, a combination of small microstructural changes appears to give rise to a significant change in strength. No significant texture or grain distortion was observed in the extensively plastically deformed region due to recrystallization.
TL;DR: In this paper, the response of polycrystalline α-zirconium to various deformation conditions was investigated through electron backscattered diffraction (EBSD) characterization.
Abstract: The response of polycrystalline α-zirconium to various deformation conditions was investigated through electron backscattered diffraction (EBSD) characterization. The range of deformation conditions included quasi-static compression and tension at room and cryogenic temperatures, along with a Taylor cylinder impact experiment. The resultant data provided spatial resolution of individual with system activity as a function of the progression of deformation. Over 300 deformation twins were analyzed to identify the type of twin system and active variant, along with the Schmid factor in the parent orientation. These data supplied information on the distribution of Schmid factor and variant rank as a function of twin system and deformation condition. Results showed significant deviation from a maximum Schmid factor activation criterion and suggest deformation twinning is greatly affected by local internal stress heterogeneities and the sense of the applied stress.
TL;DR: In this paper, the power of a diffusion-multiple approach in efficient mapping of phase diagrams and materials properties for multicomponent alloy systems, showing that many ternary phase diagrams can be mapped from a single diffusion multiple.
Abstract: This paper seeks to illustrate the power of a diffusion-multiple approach in efficient mapping of phase diagrams and materials properties for multicomponent alloy systems, showing that many ternary phase diagrams can be mapped from a single diffusion multiple. The diffusion profiles also allow evaluation of diffusion coefficients. Moreover, the composition variations created in the diffusion multiple allow efficient mapping of hardness and elastic modulus as a function of composition and phases. Examples will be given for precious metal systems currently used in high-temperature sensors. For these systems, the diffusion-multiple approach also produces a tremendous cost saving compared to making heats of various alloys, preparing samples, and measuring properties. This approach uses several microanalytical techniques, such as electron probe microanalysis, electron backscatter diffraction, and instrumented nanoindentation.
TL;DR: In this article, the effect of dynamic recrystallization on lattice preferred orientation (LPO) in olivine was investigated through the combination of two SEM-based techniques, electron backscattered diffraction (EBSD) technique for crystallographic orientation measurement and Backscattered electron imaging (BEI) for dislocation observation.
TL;DR: In this article, the evolution of microstructure and texture in two ferritic stainless steels was investigated in order to identify the existence of grain colonies associated with ridging and their origin.
Abstract: The evolution of microstructure and texture in two ferritic stainless steels was investigated in order to identify the existence of grain colonies associated with ridging and their origin. Special attentions were placed upon examining how the columnar crystals with an initial [001]//ND orientation in continuously-cast slabs can affect the formation of the grain colonies or band structures in the cold-rolled sheet specimens. The rolling and recrystallization textures at each process stage were examined by the orientation distribution function (ODF). Micro-texture measurements using an electron back-scattered diffraction (EBSD) technique were carried out on the ND, RD, and TD section, respectively. The existence of grain colonies having both {001} and {112} orientations at the central region of the sheets was clearly identified. These orientations were caused by both the crystal rotation toward a-fibre texture, which is stable orientation during rolling and the suppressed recrystallization. The relation between the presence of grain colonies and ridging phenomena was discussed.
TL;DR: In this paper, the influence of copper type shear bands on recrystallization behavior during post-deformation annealing in Al-1Mg is discussed and a weak, almost random, texture associated with nucleation at shear band has been inferred.
TL;DR: In this article, the authors developed an automated, crystallographically based twin identification and quantification routine using large sets of spatially correlated electron backscattered diffraction (EBSD) data.
Abstract: This article reports on recent progress in the effort to develop an automated, crystallographically based twin identification and quantification routine using large sets of spatially correlated electron backscattered diffraction (EBSD) data. The proposed analysis scheme uses information about the most probably occurring twin types and the macroscopic stress state, taken together with the crystallographic theory of deformation twinning, to identify and classify twinned areas in a scanned cross section of a material. The key features of the analysis are identification of potential twin boundaries by their misorientation character, validation of these boundaries through comparison with the actual boundary position and twin-plane matching across the boundary, and calculation of the Schmid factors for the orientations on either side of the boundary. This scheme will allow researchers to quantify twin area fractions from statistically significant regions and, in turn, estimate twinned volume fractions with reasonable reliability.
TL;DR: In this article, the orientation of recrystallisation nuclei and their adjacent, as-deformed regions have been characterised in deformed single crystals of different metals (Cu, Ag and Cu 2%Al) in which twinning and/or shear banding occur.
TL;DR: The structural and electrical properties of metalorganic chemical vapor deposition-grown Pb(Zr035Ti065)O3 thin films ranging in thickness from 700 to 4000 A have been investigated.
Abstract: The structural and electrical properties of metalorganic chemical vapor deposition-grown Pb(Zr035Ti065)O3 thin films ranging in thickness from 700 to 4000 A have been investigated Cross-sectional scanning electron microscopy showed that these films are columnar, with grains extending through the thickness of the film High-resolution x-ray diffraction showed that while the thickest films are tetragonal, with reflections corresponding to a-type and c-type domains, films thinner than 1500 A are not Electron backscatter diffraction and hysteresis loop measurements showed that the thinnest films are ferroelectric and have a rhombohedral crystal structure
TL;DR: In this paper, a multiscale mathematical model of the VAR process is presented that simulates the macroscopic heat and momentum transport and combines it with a mesoscopic model of nucleation and growth of grains.
Abstract: Tree-ring grain formations, a common microstructural feature found in vacuum arc remelted (VAR) ingots of nickel-based superalloys, were characterized experimentally in Part I. The experimental observations led to the conclusion that tree rings are chains of fine-equiaxed grains interrupting a predominately columnar-dendritic structure. Several possible mechanisms for their formation were considered, and their implications correlated with experimental observations. The most likely mechanism was determined to be that process perturbations cause changes in the thermal (or solutal) fields ahead of the columnar-dendrite tips, temporarily altering the conditions to increase grain nucleation and, hence, forming fine-equiaxed grains. In this article, Part II, a multiscale mathematical model of the VAR process is presented that simulates the macroscopic heat and momentum transport and combines it with a mesoscopic model of the nucleation and growth of grains. Using this multiscale model, the transient development of the VAR grain structure was simulated with varying levels and durations of fluctuations in the principal process parameters: power supply, arc focus, melt rate, and the ingot-crucible heat-transfer coefficient. The simulations were shown to agree with optical and electron back-scattered diffraction (EBSD) measurements of grain morphology and crystallographic orientation. The model results predict that tree-ring structures (consistent with those observed experimentally) can be formed by process perturbations that alter the thermal field conditions at the solidification front. A sensitivity study of the effect of the different process fluctuations on the microstructure formation was performed, providing process maps predicting the range of conditions where tree rings will not form.
TL;DR: In this article, the crystallographic preferred orientation (CPO) of a porphyroclastic-rich plagioclase layer and an equigranular plagiocase layer in an amphibolite facies shear zone from Harris, Scotland, were investigated in order to study their CPOs and deformation mechanisms.
TL;DR: The rate of oxide formation, determined from potentiodynamic and capacitive measurements, and EBSD pattern quality, increases with decreasing surface atom density, and the crystallinity and epitaxy of the oxides can depend on the orientation of the base metal causing a variation in ion conductivity.
Abstract: Passivation on polycrystalline Zr (hcp) and Ta (bcc) depends on the crystallographic orientation of the individual grains, determined by electron back scattering diffraction (EBSD). Microelectrochemical experiments yield characteristic data, such as oxide formation potentials, formation factors, capacities, and thicknesses, of local oxide formation on single grains. Strong differences occur on Zr, for Ta only a small influence of crystallographic orientation is observed. The rate of oxide formation, determined from potentiodynamic and capacitive measurements, and EBSD pattern quality, increases with decreasing surface atom density. The dominating influence can be described by the Euler angle ϕ, the second angle ϕ2 has a smaller influence. The differences in surface atom density lead to a specific current-dependent potential drop during oxide growth and therefore to a shift in the oxide formation potential.
Furthermore the crystallinity and epitaxy of the oxides can depend on the orientation of the base metal causing a variation in ion conductivity.