Correlation between Orientation Spread and Ear Forming of As-Annealed AA5151 Aluminum Alloy.

In the present work, we take the influences of activated slip systems and the orientation spread into account to predict the cup height using analytical earing models and compare the predicted results with experimental results. The effect of boundary conditions of the various stress states and the work hardening exponents are compared and discussed for profile of single crystals. A stress ratio of -0.3 and a hardening exponent of 0.3 are selected for the prediction of earing profiles. The combination of activation of the single slip systems and orientation spread provides the best prediction of deep-drawing profiles. With further consideration of the orientation spread, an increase in the total orientation leads to peak-broadening, i.e., broad and smooth ears. Furthermore, the difference of the height between the maximum and minimum value of cup profiles is reduced because of the orientation spread. The profile for C is found with single ear at 45°, while the other components individually reveal double ears at 35° and 50° for S, at 15° and 45° for B, at 0° and 90° for Cube, at 5° and 90° for r-Cube, and at 15° and 90° for G. Herein, simple analytical earing models are proposed to understand the effects of slip systems and the orientation spread. The deep-drawing profiles are predicted with six major texture components.

Polynomial fitting method of background correction for electron backscatter diffraction patterns.

A raw electron backscatter diffraction (EBSD) signal can be empirically decomposed into a Kikuchi diffraction pattern and a smooth background. For pattern indexing, the latter is generally undesirable but can reveal topographical, compositional, or diffraction contrast. In this study, we proposed a new background correction method using polynomial fitting (PF) algorithm to obtain clear Kikuchi diffraction patterns for some applications in nonconductive materials due to coating problems, at low accelerated voltage and at rough sample surfaces and for the requirement of high pattern quality in HR-EBSD. To evaluate the quality metrics of the Kikuchi patterns, we initially used three indices, namely, pattern quality, Tenengrad variance, and spatial-spectral entropy-based quality to detect the clarity, contrast, and noise of Kikuchi patterns obtained at 5 and 15 kV. Then, we examined the performance of PF method by comparing it with pattern averaging and Fourier transform-based methods. Finally, this PF background correction is demonstrated to extract the background images from the blurred diffraction patterns of EBSD measurements at low kV accelerating voltage and with coating layer, and to provide clear Kikuchi patterns successfully.

Hydrothermal-aging-induced lattice distortion in yttria-stabilized zirconia using EBSD technique.

The destabilization problem is of importance in the application of yttria-stabilized zirconia (YSZ) bio-ceramic in the oral environment due to phase transformation between tetragonal to monoclinic. Thus, in this study, the lattice distortion induced by hydrothermal aging in yttria-stabilized zirconia (YSZ) was investigated, in which YSZ specimens were subjected to hydrothermal-aging treatment for 0-48 h. The Kikuchi-band based method was employed to calculate the lattice distortion after phase transformation and the results from EBSD were compared with these obtained by X-ray diffraction (XRD). Both measurement methods showed a similar tendency of the lattice change in the a- and c- axes. EBSD results showed that the strain rates were 7.98 % and -5.03 % at the a- and c-axes, respectively. A significant decrease in the c/a ratio from 1.429 to 1.257 for the tetragonal matrix after 48 h aging is observed, which indicated Kikuchi-band based method using EBSD technique can successfully determine the local strain in tetragonal matrices.

Anisotropic Pinning-Effect of Inclusions in Mg-Based Low-Carbon Steel.

In this study, the effect of austenite grain size on acicular ferrite (AF) nucleation in low-carbon steel containing 13 ppm Mg is determined. The average austenite grain size was calculated using OM Leica software. Results show that the predicted and experimental values of austenite grain size are extremely close, with a deviation of less than 20 µm. AF formation is difficult to induce by either excessively small and large austenite grain sizes; that is, an optimal austenite grain size is required to promote AF nucleation probability. The austenite grain size of 164 µm revealed the highest capacity to induce AF formation. The effects of the maximum distance of carbon diffusion and austenite grain size on the microstructure of Mg-containing low carbon steel are also discussed. Next, the pinning ability of different inclusion types in low-carbon steel containing 22 Mg is determined. The in situ observation shows that not every inclusion could inhibit austenite grain migration; the inclusion type influences pinning ability. The grain mobility of each inclusion was calculated using in situ micrographs of confocal scanning laser microscopy (CSLM) for micro-analysis. Results show that the austenite grain boundary can strongly be pinned by Mg-based inclusions. MnS inclusions are the least effective in pinning austenite grain boundary migration.

Resolution of transmission electron backscatter diffraction in aluminum and silver: Effect of the atomic number.

This work aims to investigate the influence of intrinsic and extrinsic factors on the physical resolution of the transmission electron backscattered diffraction technique (t-EBSD) in aluminum and silver. Here, we focus on the intrinsic factors, namely, atomic number and thickness of the specimen, and extrinsic set-up factors, which include the electron beam voltage, working distance, and specimen tilt. The working distance and tilt angle, which are selected as 12 mm and 60° for Al and 12 mm and 50° for Ag, respectively, reveal a sharp pattern with high contrast. The physical resolutions at the lateral and longitudinal directions depend on the depth resolution. The depth and lateral and longitudinal resolutions increase in Al but decrease in Ag with increased accelerating voltage. The decrease in specimen thickness for Al and Ag from 400 nm to 100 nm reduces the lateral and longitudinal resolutions. The most ideal depth and lateral and longitudinal resolutions obtained under a thickness of 100 nm are 22.7, 18.9, and 33.7 nm at 30 kV for Ag and 34.7, 22.8, and 36.6 nm at 15 kV for Al, respectively.

A new method for detection of single nucleotide polymorphism in a female reproduction-associated gene, tmigd1, of Anas platyrhynchos using a strip biosensor with gold nanoparticles.

In this study, we first reported a lateral flow assay combined with primer extension (PEXT) and gold nanoparticles for single-nucleotide polymorphism (SNP) genotyping of the tmigd1 gene of the Tsaiya ducks (Anas platyrhynchos), which has the advantages of simplicity of operation, cost-effectiveness, and time-saving. Gold nanoparticles were tailed with thiol-thymine oligodeoxyribonucleotides (thiol-(dT)30) using the salt-aging method at 25°C and used as a label in a lateral flow assay. The lateral flow device was composed of test and control zones on a nitrocellulose membrane containing streptavidin and adenosine oligodeoxyribonucleotides ((dA)30), respectively. When the specific SNP existed, the corresponding primers were extended, and the reaction product was captured by streptavidin at the test zone owing to the introduction of biotin-deoxyuridine triphosphate (biotin-dUTP) into the reaction product during PEXT. Gold nanoparticles hybridized with the reaction product to render it visible. Here, we developed a new system for detection of single nucleotide polymorphism in a female reproduction-associated gene, tmigd1, of Anas platyrhynchos using the strip biosensor, and identified the optimized parameters for the concentration of Mg2+ in the PEXT reaction and the amount of streptavidin used on membranes for signal specificity.

Effects of accelerating voltage and specimen thickness on the spatial resolution of transmission electron backscatter diffraction in Cu.

A quantitative approach was proposed to determine the spatial resolution of transmission electron backscatter diffraction (t-EBSD) and to understand the limits of spatial resolution of t-EBSD. In this approach, Cu bicrystals and digital image correlation were employed. The effects of accelerating voltage and specimen thickness on the spatial resolution of t-EBSD were also investigated. t-EBSD specimens with 8µm×10µm dimensions and different thicknesses were prepared using focused ion beam milling. The optimized quality of Kikuchi pattern was achieved at a working distance of 12mm and a tilting angle of 20°. The optimum depth resolution of 34.4nm was observed in the lower surface of a 100nm thick sample at 25kV. Thus, the penetration depth from the upper surface is 65.6nm. The optimum lateral and longitudinal resolutions obtained from a 100nm thick sample at 30kV are 25.2 and 43.4nm, respectively. The spatial resolution of t-EBSD can be enhanced by increasing the accelerating voltage and decreasing the sample thickness.

EBSD and electron channeling study of anomalous slip in oligocrystals of high chromium ferritic stainless steel.

In the present study, electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI) techniques were applied to investigate the deformation pattern of coarse ferrite grains after being subjected to 3%, 6%, and 10% tensile deformation. Oligocrystals of Crofer® 22H ferritic steel were obtained as experimental material at 1075°C for 22min annealing. Using kernel average misorientation (KAM) mapping obtained from EBSD, possible slip planes are (110), (101), (12-1) and (32-1) in grain A; (0-11), (-101), (-112), (1-21) in grain B; and (0-11), (1-21) and (11-2) in grain C. Combining ECCI and EBSD techniques enables us to identify two a0[11¯1]/2 edge dislocations that occur on the (110)[1-11] and (32-1)[1-11] slip systems for grain A, thereby breaking down Schmid's law.

Characterization of Laves phase in Crofer 22 H stainless steel.

This study investigated the effect of annealing temperature on the precipitation behavior of Crofer(®) 22 H at 600°C, 700°C, and 800°C. The grain size distribution, precipitate phase identification, and microstructure were analyzed using electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDS). The morphology of Laves phase (Fe,Cr,Si)(2)(Nb,W) precipitates having the Cr(2)Nb structure changed from strip-like to needle-shaped as the annealing temperature was increased. The precipitates of the Laves phase also shifted from the grain boundaries to the grain interiors when the temperature was increased. However, the average grain size (150 µm) of the ferritic matrix did not significantly change at 600°C, 700°C, and 800°C for 10 h.

Effect of Annealing Temperature and Oxygen Flow in the Properties of Ion Beam Sputtered SnO-2x Thin Films.

Tin oxide (SnO2-x) thin films were prepared under various flow ratios of O2/(O2 + Ar) on unheated glass substrate using the ion beam sputtering (IBS) deposition technique. This work studied the effects of the flow ratio of O2/(O2 + Ar), chamber pressures and post-annealing treatment on the physical properties of SnO2 thin films. It was found that annealing affects the crystal quality of the films as seen from both X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. In addition, the surface RMS roughness was measured with atomic force microscopy (AFM). Auger electron spectroscopy (AES) analysis was used to obtain the changes of elemental distribution between tin and oxygen atomic concentration. The electrical property is discussed with attention to the structure factor.

The effect of atomic mass on the physical spatial resolution in EBSD.

In this study, bicrystals of silver (Ag) and aluminum (Al) were used to investigate the physical spatial resolution of the electron backscatter diffraction system combining a digital image correlation method. Furthermore, the effect of the accelerating voltage and probe current was investigated on the physical spatial resolution of the lateral and longitudinal resolutions for Ag and Al, respectively. The lateral and longitudinal resolutions show high dependency on the accelerating voltage for a low atomic mass material of Al, In addition, these are almost independent of the accelerating voltage for a high atomic mass material of Ag. Moreover, the probe current does not play any role on both the lateral and longitudinal resolutions. The best lateral resolutions for Al and Ag are 40.5 and 12.1 nm at 10 kV and 1 nA, respectively. The best longitudinal resolutions of 23.2 and 80 nm were obtained at 10 kV and 1 nA for Al and Ag, respectively.

Comparison of deformation texture in FePd alloy via X-ray diffraction and electron backscatter diffraction techniques.

In this work, textures measured by electron backscatter diffraction (EBSD) and X-ray diffraction in rolled FePd alloys were compared. The effect of scanning size used for EBSD measurements was investigated. The correlation coefficient was first proposed to quantify the similarity of the orientation density profile along the α- and ß-fibers after cold rolling. The correlation coefficient is approximately 1 for a scanning step range of 1-20 µm after 50% and 88% reduction. A large scanning step can capture the main components of the macrotexture in EBSD measurements. Thus, the macrotexture measured by EBSD provides another method for the quality control of texture.

Effect of microscopic parameters on EBSD spatial resolution.

In this study, a quantitative approach is proposed to understand the effect of the accelerating voltage and the probe current on the physical resolution of EBSD. The accelerating voltage was varied from 5 to 30kV and probe currents of 1, 10, and 40nA were selected. The lateral, longitudinal, and depth resolutions at 10kV and 1nA were 34.5, 44.7, and 46nm for copper, respectively. When the accelerating voltage was in the range of 5-20kV, the ratio of the longitudinal to the lateral resolution was below the theoretical ratio of 2.9. Considering the channeling effect, the best physical depth resolution of 38nm was achieved at 5kV and 10nA. The physical depth resolution in an EBSD measurement is much larger due to the channel effect than that obtained without considering this effect.