Search NASA⌕ Search

SEARCH · Search NASA

Results for “texture analysis”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

The Mechanical and Corrosion Properties of Hot-Rolled TiB{sub 2}/Ni Composites

To quickly prepare TiB{sub 2}/Ni composites at low temperatures, a method combining spark plasma sintering and hot rolling was used. This paper presents the preparation, microstructural and mechanical properties, strengthening mechanism and corrosion properties of TiB{sub 2}/Ni composites in detail. X-ray diffraction analysis shows that the texture degree of the TiB{sub 2}/Ni composites after hot rolling greatly differed from that of the as-rolled pure Ni samples. The addition of TiB{sub 2} particles limited grain growth in the Ni matrix and led to grain refinement. Dislocation strengthening, grain refinement strengthening and load transfer strengthening contributed to a 30% increase in the tensile strength compared to that of the as-rolled pure Ni. In addition, the strengthening mechanism of the mechanical property reinforcement was analyzed. The electrochemical test results demonstrate that the as-rolled pure Ni exhibited a lower corrosion current density and corrosion resistance than the other as-rolled TiB{sub 2}/Ni composites fabricated in this paper. This work demonstrates a new approach for fabricating composites in less time at lower preparation temperatures than conventional methods.

36 MATERIALS SCIENCE↗
DOE OSTI2016

In-situ laser ultrasonic measurement of the hcp to bcc transformation in commercially pure titanium

Using a novel in-situ laser ultrasonic technique, the evolution of longitudinal velocity was used to measure the α − β transformation during cyclic heating and cooling in commercially pure titanium. In order to quantify the transformation kinetics, it is shown that changes in texture can not be ignored. This is particularly important in the case of titanium where significant grain growth occurs in the β-phase leading to the ultrasonic wave sampling a decreasing number of grains on each thermal treatment cycle. Electron backscatter diffraction measurements made postmortem in the region where the ultrasonic pulse traveled were used to obtain an estimate of such local texture and grain size changes. An analysis technique for including the anisotropy of wave velocity depending on local texture is presented and shown to give self consistent results for the transformation kinetics. - Highlights: • Laser ultrasound and EBSD interpret the hcp/bcc phase transformation in cp-Ti. • Grain growth and texture produced variation in velocity during similar treatments. • Texture was deconvoluted from phase addition to obtain transformation kinetics.

36 MATERIALS SCIENCE↗
DOE OSTI2017

A method to generate small-scale, high-resolution sedimentary bedform architecture models representing realistic geologic facies

Small-scale (mm to m) sedimentary structures (e.g. ripple lamination, cross-bedding) have received a great deal of attention in sedimentary geology. The influence of depositional heterogeneity on subsurface fluid flow is now widely recognized, but incorporating these features in physically-rational bedform models at various scales remains problematic. The current investigation expands the capability of an existing set of open-source codes, allowing generation of high-resolution 3D bedform architecture models. The implemented modifications enable the generation of 3D digital models consisting of laminae and matrix (binary field) with characteristic depositional architecture. The binary model is then populated with petrophysical properties using a textural approach for additional analysis such as statistical characterization, property upscaling, and single and multiphase fluid flow simulation. One example binary model with corresponding threshold capillary pressure field and the scripts used to generate them are provided, but the approach can be used to generate dozens of previously documented common facies models and a variety of property assignments. An application using the example model is presented simulating buoyant fluid (CO 2 ) migration and resulting saturation distribution.

58 GEOSCIENCES↗
DOE OSTI2023

Epitaxial growth of hexagonal BaNi O 3–δ thin films on SrTi O 3 (111) substrates

Transition metal oxides containing nickel species in oxidation states higher than 3+ often exhibit high catalytic activity, which makes them promising for applications as advanced electrocatalysts for water splitting and fuel cells. Here, we examine the structure and properties of BaNiO 3 (BNO) thin films, containing formally Ni 4+ , grown on SrTiO 3 (111) substrates using oxygen-plasma–assisted molecular beam epitaxy. X-ray diffraction and scanning transmission electron microscopy measurements reveal that BNO films have a hexagonal structure with $c$- and $a$-axes of mixed textures showing epitaxial relationships BNO (0001) ∥ SrTiO 3 (111) and BNO (10$\overline{1}$0) ∥ SrTi O 3 (111), respectively. The formation of the $a$-axis texture is dominant due to the smaller lattice mismatch with the substrate. Here, density functional theory calculations confirm that the hexagonal BNO film with the $a$-axis texture is energetically more favorable than the competing $c$-axis texture. Detailed spectroscopy data analysis indicates that hexagonal BNO films contain mixtures of Ni 2+ , Ni 3+ , and Ni 4+ species, with Ni 4+ being dominant. Our study provides insights into stabilizing Ni 4+ in complex oxides, which is important for further exploration of the potential of materials containing Ni 4+ .

36 MATERIALS SCIENCE↗
DOE OSTI2020

Analysis of Dust Samples Collected from an Inland ISFSI Site (Site A)

In September of 2020, dust samples were collected from the surface of spent nuclear fuel (SNF) dry storage canisters during an inspection at an inland Independent Spent Fuel Storage Installation. The purpose of the sampling was to assess the composition and abundance of the soluble salts present on the canister surface, information which provides a metric for potential corrosion risks. The samples were delivered to Sandia National laboratories for analysis. At Sandia, the soluble salts were leached from the dust and quantified by ion chromatography. In addition, subsamples of the dust were taken for scanning electron microscope analysis to determine the texture and mineralogy of the dust and salts. The results of those analyses are presented in this report.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1976

Petrology of lunar rocks and implication to lunar evolution

Recent advances in lunar petrology, based on studies of lunar rock samples available through the Apollo program, are reviewed. Samples of bedrock from both maria and terra have been collected where micrometeorite impact penetrated the regolith and brought bedrock to the surface, but no in situ cores have been taken. Lunar petrogenesis and lunar thermal history supported by studies of the rock sample are discussed and a tentative evolutionary scenario is constructed. Mare basalts, terra assemblages of breccias, soils, rocks, and regolith are subjected to elemental analysis, mineralogical analysis, trace content analysis, with studies of texture, ages and isotopic composition. Probable sources of mare basalts are indicated.

Ridley, W. I.↗
NASA NTRS1984

Recent advances in geologic mapping by radar

Quantitative techniques are available which allow the analysis of SAR images for the derivation of geological surface and process data. In conjunction with calibrated radar sensors operating at several incidence angles, wavelengths, and polarizations, the compilation of multiparameter radar signatures of lithological and geomorphic units can accordingly proceed for geological mapping in unknown areas. While radar image tone can be used in arid zones to derive surface micromorphology, heavily vegetated tropical regions require the analysis of radar image texture by means of Fourier techniques which decompose the image into bandpasses that represent different scales of texture.

Farr, T. G.↗
NASA NTRS1997

Environmental Assessment and Monitoring with ICAMS (Image Characterization and Modeling System) Using Multiscale Remote-Sensing Data

With the rapid increase in spatial data, especially in the NASA-EOS (Earth Observing System) era, it is necessary to develop efficient and innovative tools to handle and analyze these data so that environmental conditions can be assessed and monitored. A main difficulty facing geographers and environmental scientists in environmental assessment and measurement is that spatial analytical tools are not easily accessible. We have recently developed a remote sensing/GIS software module called Image Characterization and Modeling System (ICAMS) to provide specialized spatial analytical tools for the measurement and characterization of satellite and other forms of spatial data. ICAMS runs on both the Intergraph-MGE and Arc/info UNIX and Windows-NT platforms. The main techniques in ICAMS include fractal measurement methods, variogram analysis, spatial autocorrelation statistics, textural measures, aggregation techniques, normalized difference vegetation index (NDVI), and delineation of land/water and vegetated/non-vegetated boundaries. In this paper, we demonstrate the main applications of ICAMS on the Intergraph-MGE platform using Landsat Thematic Mapper images from the city of Lake Charles, Louisiana. While the utilities of ICAMS' spatial measurement methods (e.g., fractal indices) in assessing environmental conditions remain to be researched, making the software available to a wider scientific community can permit the techniques in ICAMS to be evaluated and used for a diversity of applications. The findings from these various studies should lead to improved algorithms and more reliable models for environmental assessment and monitoring.

Lam, N.↗
NASA NTRS2005

NWA 2736: An Unusual New Graphite-bearing Aubrite

Aubrites are enstatite-rich achondrites that are probably related to enstatite chondrite parent bodies. The exact link, if any, is not understood. They may have formed from melting within one or more enstatite chondrite parent bodies. Description of NWA 2736: One complete stone weighing 171.51 grams was recovered from the Sahara Desert by nomads sometime before September 2004. It was completely covered with fusion crust and desert varnish. This stone is severely weathered, with caramel brown coloration throughout and calcite veins that extend into the interior of the sample. Mineral analyses were performed and elemental x-ray maps were obtained with a CAMECA SX-50 electron microprobe at the Lunar and Planetary Laboratory at the University of Arizona. The relatively high modal abundance of albitic plagioclase, presence of euhedral graphite, depletion of troilite, and occurrence of pervasive kamacite veins (some with daubreelite) all indicate that NWA 2736 has a complex history and may sample a new region of the aubrite parent body. A discussion and analysis on the overall texture of NWA 2736 is presented.

Lowe, J. J.↗
NASA NTRS2001

Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features ranged from tens to a few microns with textures that remained relatively sharp and were crystallographically controlled. These results were comparable to that observed in the "naturally" weathered comparison/reference grains. Chemical analysis by EDS indicates these textures correlated with the relative loss of Mg and Fe cations by diffusional processes. In contrast the biotic results indicated changes in the etching patterns on the scale of hundreds of nm, which are neither sharp nor crystallographically controlled (nanoetching). Organisms, organic debris and/or extracellular polymeric substances (biofilm) were often in close proximity or direct contact with the nanoetching. While there are many poorly constrained variables in natural weathering experiments to contend with, such as the time scale, the chemistry of the fluids and degree of biologic participation, some preliminary observations can be made: (1) certain distinct surface textures appear correlated with the specific processes giving rise to these textures; (2) the process of diffusing cations can produce many similar styles of surface textural changes; and (3) the main difference between abiotic and biotically produced weathering is the scale (microns versus nanometers) and the style (crystallographically versus noncrystallographically controlled) of the textural features. Further investigation into nanosize scale surface textures should attempt to quantify both textures and chemical changes of the role of microorganisms in the weathering of silicates. Additional experiments addressing nanoscale textures of shock features for comparison with the current data set.

Longazo, Teresa G.↗
NASA NTRS1973

Texturing in metals as a result of sliding

Sliding friction experiments were conducted with copper, nickel, iron, and cobalt sliding on themselves in air and argon. The resulting wear surfaces were examined with X-ray analysis to determine if surface texturing had occurred as a result of sliding. Results of the investigation indicate that, for the face-centered-cubic metals copper and nickel, a (111) texture develops with the (111) planes tilted 10 deg in the direction of sliding. The body-centered-cubic metal iron exhibited a (110) texture with the (100) direction oriented in the direction of sliding. It also exhibited a 10 deg tilt in the direction of sliding. The environment influenced the results in that the degree of texture observed in argon was less than that seen in air for iron. No texturing was observed for the close-packed-hexagonal metal cobalt. Recrystallization was observed with copper as a result of sliding.

Wheeler, D. R.↗
NASA NTRS1975

Texturing in metals as a result of sliding

Sliding friction experiments were conducted with copper, nickel, iron and cobalt sliding on themselves in air and argon. The resulting wear surfaces were examined by X-ray analysis to determine if surface texturing had occurred as a result of sliding. Results of the investigation indicate that, for the face-centered-cubic metals copper and nickel, a (111) texture develops with the (111) planes tilted 10 deg in the direction of sliding. The body-centered-cubic metal iron exhibited a (110) texture with the (111) direction oriented in the direction of sliding. It also exhibited a 10 deg tilt in the direction of sliding. The environment influenced the results in that the degree of texture observed in argon was less than that seen in air for iron. No texturing was observed for the close-packed-hexagonal metal cobalt. Recrystallization was observed with copper as a result of sliding.

Wheeler, D. R.↗
NASA NTRS1992

Disk-resolved photometric analysis of Europan terrains

The photometric textures of Europa geologic units possessing the same small mean photometric slope angle as found by Dominique et al. (1991) are presently examined on the basis of Hapke's (1981) photometric model. With only one exception, the particles composing the surfaces of most of the units exhibit similar scattering properties. Attention is given to the single-particle scattering functions of the two bright plains regions examined; these are noted to be no less different from each other than both are from the other units. An aging process that affects the albedos and single-particle phase functions is hypothesized for Europa.

Domingue, Deborah↗
DOE OSTI2026

Symmetry-protected topological polarons

Emergent quasiparticles in solids often exhibit unique topological properties as a result of the complex interplay between charge, orbital, spin, and lattice degrees of freedom. Among these quasiparticles, the polaron occupies a special place as the first known manifestation of the interaction between a fermion and a boson field. While polarons have been investigated for almost a century, whether these quasiparticles exhibit topological properties and why remain open questions. Here, we establish the universal symmetry principles governing the topology of polar textures in large polarons. Using a group-theoretic analysis, we identify four distinct classes of polar textures in time-reversal-invariant systems, and we show that they carry integer topological charges. We validate this classification by performing state-of-the-art first-principles calculations of materials representative of each class. For these materials, we compute the fingerprints of polaron topology in Huang diffuse scattering and propose ultrafast electron and X-ray scattering experiments to detect these quasiparticles.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Grain boundary plane distributions in a cold rolled and annealed high purity iron

High purity (99.99%) iron samples were cold rolled with a thickness reduction of 87% followed by a annealing at 620 °C for 15 and 45 min, then the grain boundary plane distributions were characterized by electron backscatter diffraction and a stereology and statistics based five parameter analysis. The results showed that the grain boundary planes were mainly distributed on (1 0 0) and such distribution was enhanced obviously when the holding time of annealing increased from 15 to 45 min during which an extensive grain growth and a dramatic texture evolution took place. Further analysis indicated such distribution was largely due to the rotation of grain boundary planes of the [1 0 0] misoriented grains. Additionally, it was also observed that some random boundaries of [1 0 0] misoriented grains were changing from asymmetrical tilt into (1 0 0)/(− 1 0 0) twist when annealing proceeded from 15 to 45 min. Based on the present work and the results reported by other investigators, it was suggested that the chemistry appeared to be critical in determining the grain boundary plane distribution in iron based materials. - Highlights: •Grain boundary (GB) plane distribution (GBPD) in a high purity (99.99%) was studied. •GB planes are mainly distributed on (1 0 0) in the cold rolled and annealed samples. •Such distribution is largely due to the rotation of GB planes of [100] misoriented grains. •Some [1 0 0] asymmetrical tilt boundaries are evolving into twist ones during annealing.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Conservation management decreases surface runoff and soil erosion

Conservation management practices – including agroforestry, cover cropping, no-till, reduced tillage, and residue return – have been applied for decades to control surface runoff and soil erosion, yet results have not been integrated and evaluated across cropping systems. In this study we collected data comparing agricultural production with and without conservation management strategies. We used a bootstrap resampling analysis to explore interactions between practice type, soil texture, surface runoff, and soil erosion. We then used a correlation analysis to relate changes in surface runoff and soil erosion to 13 other soil health and agronomic indicators, including soil organic carbon, soil aggregation, infiltration, porosity, subsurface leaching, and cash crop yield. Across all conservation management practices, surface runoff and erosion had respective mean decreases of 67% and 80% compared with controls. Use of cover cropping provided the largest decreases in erosion and surface runoff, thus emphasizing the importance of maintaining continuous vegetative cover on soils. Coarse- and medium-textured soils had greater decreases in both erosion and runoff than fine-textured soils. Changes in surface runoff and soil erosion under conservation management were highly correlated with soil organic carbon, aggregation, porosity, infiltration, leaching, and yield, showing that conservation practices help drive important interactions between these different facets of soil health. This study offers the first large-scale comparison of how different conservation agriculture practices reduce surface runoff and soil erosion, and at the same time provides new insight into how these interactions influence the improvement or loss of soil health.

58 GEOSCIENCES↗
DOE OSTI2021

Shear assisted processing and extrusion of enhanced strength aluminum alloy tubing

Hollow extrusions are used in many industries to make strong, lightweight, and affordable structures. Shear Assisted Processing and Extrusion (ShAPE) enables the extrusion of many alloys, often with noteworthy properties. In this investigation, ShAPE was used to extrude 1 and 2 mm wall tubes of aluminum alloy 6063 measuring 12 mm in diameter at extrusion speeds up to 3.8 m/min. This speed is 10 and 15 times faster than has been reported for any alloy using ShAPE and friction stir back extrusion, respectively. Increasing the extrusion speed from 0.7 to 3.8 m/s resulted in using 68% less process energy at steady state. Microstructural analysis and tensile testing were performed on as-extruded tubes and tubes with a direct T5 heat treatment. Grain refinement from 65 µm to below 20 µm was observed. Growth of macroscale Mg 2 Si strengthening precipitates was not observed. ShAPE processing resulted in recrystallization, and extrusion speed was shown to influence final extrudate texture. Here, transmission electron microscopy analysis revealed that the as-extruded microstructure was free of nanoscale ß" strengthening precipitates. Nanoscale ß" was prominent in direct-aged (T5) ShAPE tubes, similar to a slightly over-aged conventional T6 microstructure. As-extruded tubes had ultimate tensile strengths on par with conventional T5 extrusions and approximately double the total elongation. Tubes that underwent a T5 heat treatment had yield and ultimate strengths averaging 198 and 234 MPa, respectively, with an average total elongation of 11%. The tensile test results are comparable to a conventional T6 heat treatment, but without the solutionization heat treatment step. Mechanical properties either remained flat or improved with increased extrusion speed, which suggests that ShAPE can be scaled up to an industrial process to create energy- and economically efficient high-strength extrusions.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Study of the cerrado vegetation in the Federal District area from orbital data

The physiognomic units of cerrado in the area of Distrito Federal (DF) were studied through the visual and automatic analysis of products provided by Multispectral Scanning System (MSS) of LANDSAT. The visual analysis of the multispectral images in black and white, at the 1:250,000 scale, was made based on the texture and tonal patterns. The automatic analysis of the compatible computer tapes (CCT) was made by means of IMAGE-100 system. The following conclusions were obtained: (1) the delimitation of cerrado vegetation forms can be made by the visual and automatic analysis; (2) in the visual analysis, the principal parameter used to discriminate the cerrado forms was the tonal pattern, independently of the year's seasons, and the channel 5 gave better information; (3) in the automatic analysis, the data of the four channels of MSS can be used in the discrimination of the cerrado forms; and (4) in the automatic analysis, the four channels combination possibilities gave more information in the separation of cerrado units when soil types were considered.

Dejesusparada, N.↗