Journal articles on the topic 'Microstructural differences'
To see the other types of publications on this topic, follow the link: Microstructural differences.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Microstructural differences.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Costin, Walter, Olivier Lavigne, Andrei G. Kotousov, Reza Ghomashchi, Ian H. Brown, Valerie Linton, and Frank J. Barbaro. "Susceptibility of Acicular Ferrite and Upper Bainite Microstructures to Hydrogen Assisted Cold Cracking Propagation." Materials Science Forum 909 (November 2017): 44–49. http://dx.doi.org/10.4028/www.scientific.net/msf.909.44.
Full textAbstract:
Acicular ferrite (AF) and upper bainite (UB) are microstructural constituents commonly found in ferritic weld metals. Both microstructures are formed within a similar temperature range and by the same type of transformation mechanisms. They have however, substantially different morphologies and microstructural features that govern both their mechanical properties and hydrogen embrittlement susceptibility. This work shows that despite substantial microstructural differences, the mechanical properties of both microstructural constituents were quite similar. However, the microstructural differences were found to significantly affect the hydrogen crack propagation resistance. Hydrogen assisted cold cracking (HACC) propagates along a path of least resistance through the surrounding microstructure. The unit crack path was significantly shorter for AF than for UB, which implied more frequent changes in direction and thus increased dissipation of energy from the crack driving force. These results suggest that AF, possessing fine interlocking grains and high angle grain boundaries (HAGB), increases the localised resistance to HACC propagation more than UB due to the impediment of brittle, cleavage-like crack propagation at HAGB’s.
2
Reginster, Sylvie, Anne Mertens, Hakan Paydas, Jerome Tchoufang Tchuindjang, Quentin Contrepois, Thierry Dormal, Olivier Lemaire, and Jacqueline Lecomte-Beckers. "Processing of Ti Alloys by Additive Manufacturing: A Comparison of the Microstructures Obtained by Laser Cladding, Selective Laser Melting and Electron Beam Melting." Materials Science Forum 765 (July 2013): 413–17. http://dx.doi.org/10.4028/www.scientific.net/msf.765.413.
Full textAbstract:
In this study, samples of alloy Ti-6Al-4V have been processed by different additive manufacturing techniques in order to compare the resulting microstructure. In all three processes, ultrafast cooling gives rise to strongly out-of-equilibrium microstructures. However, the specific of the heat flow in each process lead to significant differences as far as the grains orientation and the resulting microstructural anisotropy are concerned.
3
Harkness, S. D., W. Lewis, M. Bartholomeusz, and M. Tsai. "Effect of target processing on CoCrPtTa thin-film media." Journal of Materials Research 15, no. 12 (December 2000): 2811–13. http://dx.doi.org/10.1557/jmr.2000.0401.
Full textAbstract:
The ensuing paper summarizes an investigation on the effect of target microstructural morphology on resultant sputter deposited media magnetic performance. Significant differences in media magnetic coercivity were obtained from Co–Cr–Pt–Ta targets possessing the same chemistry, sputtered under identical conditions, but possessing different microstructural phase and crystallographic texture characteristics. This result was most likely caused by the difference in sputter yields for the Ta-containing phases in the two distinct target microstructures. Results support enhanced chromium segregation yielding a decrease in the intergranuler exchange energy field for the deposited thin films.
4
Nolan, T. P., R. Sinclair, T. Yamashita, and R. Ranjan. "Correlation of micro-structural, micro-chemical and micro-magnetic properties of longitudinal recording media using CM20FEG Lorentz TEM." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 892–93. http://dx.doi.org/10.1017/s042482010017219x.
Full textAbstract:
Cobalt alloy on chromium thin film magnetic media are used in industry computer hard disk drives because of their large values of coercivity (Hc), remanent magnetization (Mr), squareness (S*), and relatively low noise. The magnetic performance depends strongly on processing conditions and the resulting nanometer scale microstructure.A complete structure-processing-properties analysis requires effective measurement of magnetic and microstructural properties. To date, most structure-properties analyses have involved correlation of bulk magnetic (hysteresis loop) properties and magnetic recording measurements with physical microstructures observed by high-resolution SEM and TEM.The nanoscale microstructural features that dramatically affect magnetic properties are difficult to observe but careful TEM analysis has been used to observe subtle, important differences in the atomic scale physical microstructure. Even these impressive capabilities are becoming insufficient for continued development of improved magnetic recording media. Microstructural design is moving into a regime where appropriate control of magnetic properties requires control of elemental composition and second phase formation as well as crystallography and morphology, at near-atomic levels.
5
Tadesse, Abel, and Hasse Fredriksson. "The Effect of Inoculation on the Thermal Expansion/Contraction during Solidification of Gray Cast Iron." Materials Science Forum 790-791 (May 2014): 447–51. http://dx.doi.org/10.4028/www.scientific.net/msf.790-791.447.
Full textAbstract:
Inoculation of casting used to improve the microstructure and the properties of the component. Depending upon the area of application, gray cast iron has different microstructure and mechanical properties. The type and amount of the inoculation result in shape and orientation differences of the flake graphite. The Linear Variable Differential Transformer (LVDT) shows a variation in displacements change during the solidification. Temperature measurement used to analyze cooling curves and microstructural analysis of sample to examine the physical differences. Thermal analysis compared with the experimental results and microstructural study for describing the variation in area fraction and shape of graphite. The experimental result indicates contraction in austenite formation region, and expansion in eutectic formation region. The effect of the inoculant and the superheat temperature shows a variation in degree of expansion/contraction and cooling rates of the experiments. The comparisons between the experimental and the theoretical results have been done. Combining the theoretical and experimental results, it resembles a difference in eutectic formation region, and it needs carful investigation in future works.
6
Rubenis, Kristaps, Agnese Pura, Valdis Teteris, Janis Locs, and Jurijs Ozolins. "Effect of Shaping Method and Heat Treatment on Microstructure and Thermoelectric Properties of Titanium Dioxide." Key Engineering Materials 604 (March 2014): 240–44. http://dx.doi.org/10.4028/www.scientific.net/kem.604.240.
Full textAbstract:
The TiO2samples were obtained by two different shaping methods: cold isostatic pressing and cold extrusion, sintered in air at 1373 K, 1573 K, 1773 K and annealed under vacuum at 1373 K. Differences in density, microstructure and thermoelectric properties were observed between the samples depending on the shaping method used. With increase in sintering temperature the electrical conductivity of all samples increased while the Seebeck coefficient decreased. Great microstructural differences were observed between the surface and bulk of the samples made by each of the shaping techniques. It was found that microstructural differences between surface and bulk of the samples affect their thermoelectric properties.
7
SINGH, NANDINI C., ARCHITH RAJAN, ARCHANA MALAGI, KEERTHI RAMANUJAN, MATTEO CANINI, PASQUALE A. DELLA ROSA, PARTHA RAGHUNATHAN, BRENDAN S. WEEKES, and JUBIN ABUTALEBI. "Microstructural anatomical differences between bilinguals and monolinguals." Bilingualism: Language and Cognition 21, no. 5 (October 9, 2017): 995–1008. http://dx.doi.org/10.1017/s1366728917000438.
Full textAbstract:
DTI is an established method to study cerebral white-matter microstructure. Two established measures of DTI are fractional anisotropy (FA) and mean diffusivity (MD) and both differ for bilingual and monolingual speakers. Less is known about differences in two other measures called radial (RD) and axial diffusivity (AD). We report differences in mean RD and AD-values in the right superior longitudinal fasciculus (SLF) and forceps minor between bilingual (Hindi–English) and monolingual (English) speakers as well as differences in mean FA-values in the anterior thalamic radiation, right inferior fronto-occipital and inferior longitudinal fasciculus (ILF) and mean MD-values in forceps minor and bilateral SLF. Noteworthy, a positive correlation between L2 proficiency and mean RD-values in the right SLF was observed. We suggest that changes in the geometry of white matter tracts reflect regular bilingual language experience and contend that neuroplasticity in right SLF results from demands on cognitive control for bilingual speakers.
8
Islam, Showmic, Musa Norouzian, and Joseph A. Turner. "Influence of tessellation morphology on ultrasonic scattering." Journal of the Acoustical Society of America 152, no. 3 (September 2022): 1951–61. http://dx.doi.org/10.1121/10.0014288.
Full textAbstract:
Material properties, such as hardness, yield strength, and ductility, depend on the microstructure of the material. If the microstructural organization can be quantified nondestructively, for example, with ultrasonic scattering techniques, then it may be possible to predict the mechanical performance of a component. Three-dimensional digital microstructures have been increasingly used to investigate the scattering of mechanical waves within a numerical framework. These synthetic microstructures can be generated using different tessellation algorithms that result in different grain shapes. In this study, the variation of ultrasonic scattering is calculated for microstructures of different morphologies for a nickel polycrystal. The ultrasonic properties are calculated for the Voronoi, Laguerre tessellations, and voxel-based synthetic microstructures created by DREAM.3D. The results show that the differences in the two-point statistics and ultrasonic attenuation for different morphologies become more significant at wider size distributions and higher frequencies.
9
Hubbard, Nicholas A., Monroe Turner, Joanna L. Hutchison, Austin Ouyang, Jeremy Strain, Larry Oasay, Saranya Sundaram, et al. "Multiple sclerosis-related white matter microstructural change alters the BOLD hemodynamic response." Journal of Cerebral Blood Flow & Metabolism 36, no. 11 (July 22, 2016): 1872–84. http://dx.doi.org/10.1177/0271678x15615133.
Full textAbstract:
Multiple sclerosis (MS) results in inflammatory damage to white matter microstructure. Prior research using blood-oxygen-level dependent (BOLD) imaging indicates MS-related alterations to brain function. What is currently unknown is the extent to which white matter microstructural damage influences BOLD signal in MS. Here we assessed changes in parameters of the BOLD hemodynamic response function (HRF) in patients with relapsing-remitting MS compared to healthy controls. We also used diffusion tensor imaging to assess whether MS-related changes to the BOLD-HRF were affected by changes in white matter microstructural integrity. Our results showed MS-related reductions in BOLD-HRF peak amplitude. These MS-related amplitude decreases were influenced by individual differences in white matter microstructural integrity. Other MS-related factors including altered reaction time, limited spatial extent of BOLD activity, elevated lesion burden, or lesion proximity to regions of interest were not mediators of group differences in BOLD-HRF amplitude. Results are discussed in terms of functional hyperemic mechanisms and implications for analysis of BOLD signal differences.
10
Hao, Jia, Wang Yao, W. B. Ryan Harris, Joy Y. Vink, Kristin M. Myers, and Eve Donnelly. "Characterization of the collagen microstructural organization of human cervical tissue." Reproduction 156, no. 1 (July 2018): 71–79. http://dx.doi.org/10.1530/rep-17-0763.
Full textAbstract:
The cervix shortens and softens as its collagen microstructure remodels in preparation for birth. Altered cervical tissue collagen microstructure can contribute to a mechanically weak cervix and premature cervical dilation and delivery. To investigate the local microstructural changes associated with anatomic location and pregnancy, we used second-harmonic generation microscopy to quantify the orientation and spatial distribution of collagen throughout cervical tissue from 4 pregnant and 14 non-pregnant women. Across patients, the alignment and concentration of collagen within the cervix was more variable near the internal os and less variable near the external os. Across anatomic locations, the spatial distribution of collagen within a radial zone adjacent to the inner canal of the cervix was more homogeneous than that of a region comprising the middle and outer radial zones. Two regions with different collagen distribution characteristics were found. The anterior and posterior sections in the outer radial zone were characterized by greater spatial heterogeneity of collagen than that of the rest of the sections. Our findings suggest that the microstructural alignment and distribution of collagen varies with anatomic location within the human cervix. These observed differences in collagen microstructural alignment may reflect local anatomic differences in cervical mechanical loading and function. Our study deepens the understanding of specific microstructural cervical changes in pregnancy and informs investigations of potential mechanisms for normal and premature cervical remodeling.
11
Ralston, K. D., J. G. Brunner, S. Virtanen, and N. Birbilis. "Effect of Processing on Grain Size and Corrosion of AA2024-T3." Corrosion 67, no. 10 (October 1, 2011): 105001–105001. http://dx.doi.org/10.5006/1.3647762.
Full textAbstract:
Abstract Recent works on high-purity materials have indicated that microstructural modification via grain refinement can alternately reduce or enhance corrosion, depending on the specific material-environment combination. Generally, however, a paucity of information exists in understanding how microstructural alteration and processing, in combination with grain refinement, affects corrosion. In this work, the effect of microstructural refinement on an alloy containing a high number density of precipitates and intermetallics is explored. Grain-refined AA2024-T3 (UNS A92024) samples were produced through severe plastic deformation processes and their corrosion response was compared to control samples of commercial ingot and sheet across the pH range. Microstructure and grain size were characterized using a combination of electron backscattered diffraction and transmission electron microscopy. It is revealed that there is a difference in corrosion between the specimens (which possess nearly the same bulk chemistry) as based on anodic potentiodynamic polarization, current transient, and exposure/profilometry experiments in sodium chloride (NaCl) electrolytes. However, in all cases, the effect is dominated by the environment, micro-chemical differences, and grain size.
12
Scheriau, Stephan, Thomas Schöberl, Siegfried Kleber, and Reinhard Pippan. "Recrystallization and Grain Growth Behavior of SPD Deformed 316L Stainless Steel." Advanced Materials Research 89-91 (January 2010): 491–96. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.491.
Full textAbstract:
The microstructural evolution, the changes in microhardness and the recrystallization behavior of a modified 316L stainless steel were investigated during high pressure torsion (HPT) and subsequent annealing. To study the impact of the governing process parameters on the evolving microstructures, the applied strain, the strain path and the annealing temperatures were varied. In contrast to ordinary single phase steels, which showed a decrease in the structural size ending in a saturation of the microstructural refinement between an equivalent strain eq of 10 and 15, HPT of the modified 316L results in a steep increase in shear stress at very small strains and the saturation region is reached far before eq = 10. Studies using the transmission electron microscope (TEM) revealed that at large strains the original coarse grains are converted by the massive intersection and fragmentation of twins into a nanometer-scaled microstructure. In the case of monotonic HPT, shock annealing of the deformed discs results in rows of fine and coarse grains. In the cyclic deformed discs a homogenous, fine-grained and almost fully recrystallized microstructure was observed. The results clearly show that both the strength and ductility of the material can be significantly influenced by SPD and subsequent annealing. Possible reasons for the observed differences in the deformation and annealing behavior are discussed.
13
Ural, Nazile. "The significance of scanning electron microscopy (SEM) analysis on the microstructure of improved clay: An overview." Open Geosciences 13, no. 1 (January 1, 2021): 197–218. http://dx.doi.org/10.1515/geo-2020-0145.
Full textAbstract:
Abstract This study aims to emphasize the importance of scanning electron microscopy (SEM) in explaining the differences in the physical and mechanical behaviors of the improved clays before and after improvement. Generally, clays appear as problematic soils in the construction area. The reasons for this can be low strength, high compressibility, high level of volumetric changes, and swelling potential. The behavior of clays may not always be interpreted according to their physical and mechanical properties. In such cases, analyses are carried out according to the microstructure of the clay. Among several microstructural analyzes, SEM is very important, because the soil microstructure formed by clay particles and additives can be observed. This work discusses the studies based on the microstructural properties of the improved clay with SEM analysis. As a result of the studies carried out, it has been seen that unexplained physical or mechanical behavior can be explained by the microstructural behaviors of clay particles and additives.
14
Stephens, Rebecca L., Benjamin W. Langworthy, Sarah J. Short, Jessica B. Girault, Martin A. Styner, and John H. Gilmore. "White Matter Development from Birth to 6 Years of Age: A Longitudinal Study." Cerebral Cortex 30, no. 12 (June 27, 2020): 6152–68. http://dx.doi.org/10.1093/cercor/bhaa170.
Full textAbstract:
Abstract Human white matter development in the first years of life is rapid, setting the foundation for later development. Microstructural properties of white matter are linked to many behavioral and psychiatric outcomes; however, little is known about when in development individual differences in white matter microstructure are established. The aim of the current study is to characterize longitudinal development of white matter microstructure from birth through 6 years to determine when in development individual differences are established. Two hundred and twenty-four children underwent diffusion-weighted imaging after birth and at 1, 2, 4, and 6 years. Diffusion tensor imaging data were computed for 20 white matter tracts (9 left–right corresponding tracts and 2 commissural tracts), with tract-based measures of fractional anisotropy and axial and radial diffusivity. Microstructural maturation between birth and 1 year are much greater than subsequent changes. Further, by 1 year, individual differences in tract average values are consistently predictive of the respective 6-year values, explaining, on average, 40% of the variance in 6-year microstructure. Results provide further evidence of the importance of the first year of life with regard to white matter development, with potential implications for informing early intervention efforts that target specific sensitive periods.
15
Reislev, Nina Linde, Tim Bjørn Dyrby, Hartwig Roman Siebner, Ron Kupers, and Maurice Ptito. "Simultaneous Assessment of White Matter Changes in Microstructure and Connectedness in the Blind Brain." Neural Plasticity 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/6029241.
Full textAbstract:
Magnetic resonance imaging (MRI) of the human brain has provided converging evidence that visual deprivation induces regional changes in white matter (WM) microstructure. It remains unclear how these changes modify network connections between brain regions. Here we used diffusion-weighted MRI to relate differences in microstructure and structural connectedness of WM in individuals with congenital or late-onset blindness relative to normally sighted controls. Diffusion tensor imaging (DTI) provided voxel-specific microstructural features of the tissue, while anatomical connectivity mapping (ACM) assessed the connectedness of each voxel with the rest of the brain. ACM yielded reduced anatomical connectivity in the corpus callosum in individuals with congenital but not late-onset blindness. ACM did not identify any brain region where blindness resulted in increased anatomical connectivity. DTI revealed widespread microstructural differences as indexed by a reduced regional fractional anisotropy (FA). Blind individuals showed lower FA in the primary visual and the ventral visual processing stream relative to sighted controls regardless of the blindness onset. The results show that visual deprivation shapes WM microstructure and anatomical connectivity, but these changes appear to be spatially dissociated as changes emerge in different WM tracts. They also indicate that regional differences in anatomical connectivity depend on the onset of blindness.
16
Nolan, T. P., R. Sinclair, T. Yamashita, and R. Ranjan. "Correlation of microstructural and magnetic properties of longitudinal recording media using TEM." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1016–17. http://dx.doi.org/10.1017/s0424820100150915.
Full textAbstract:
Cobalt alloy on chromium thin film media are used in industry because of their large values of coercivity (Hc), remanent magnetization (Mr), squareness (S*), and relatively low noise. The magnetic properties depend strongly on processing conditions and, as will be shown, the resulting microstructure.A complete structure-processing-properties analysis requires effective measurement of both magnetic and microstructural properties. Direct micromagnetic-microstructural comparison is not yet readily available, but bulk hysteresis loop parameters are reproducible and highly correlated with both desired recording characteristics and microstructures, and so provide a valuable, albeit indirect comparison. Signal to noise (S/N) measurements are also used as a more direct measure of usefulness in a high density disk drive. The nanoscale microstructural features which dramatically affect these bulk magnetic properties are difficult to observe. However, careful combination of TEM techniques, including bright-field, dark-field, high-resolution, selected area diffraction and elongated-probe microdiffraction can determine the subtle microstructural differences.
17
Coad, Bethany M., Emma Craig, Rebecca Louch, John P. Aggleton, Seralynne D. Vann, and Claudia Metzler-Baddeley. "Precommissural and postcommissural fornix microstructure in healthy aging and cognition." Brain and Neuroscience Advances 4 (January 2020): 239821281989931. http://dx.doi.org/10.1177/2398212819899316.
Full textAbstract:
The fornix is a key tract of the hippocampal formation, whose status is presumed to contribute to age-related cognitive decline. The precommissural and postcommissural fornix subdivisions form respective basal forebrain/frontal and diencephalic networks that may differentially affect aging and cognition. We employed multi-parametric magnetic resonance imaging (MRI) including neurite orientation density and dispersion imaging, quantitative magnetization transfer (qMT), and T1-relaxometry MRI to investigate the microstructural properties of these fornix subdivisions and their relationship with aging and cognition in 149 asymptomatic participants (38–71 years). Aging was associated with increased free water signal and reductions in myelin-sensitive R1 and qMT indices but no apparent axon density differences in both precommissural and postcommissural fibers. Precommissural relative to postcommissural fibers showed a distinct microstructural pattern characterised by larger free water signal and axon orientation dispersion, with lower apparent myelin and axon density. Furthermore, differences in postcommissural microstructure were related to performance differences in object-location paired-associate learning. These results provide novel in vivo neuroimaging evidence for distinct microstructural properties of precommissural and postcommissural fibers that are consistent with their anatomy as found in axonal tracer studies, as well as for a contribution of postcommissural fibers to the learning of spatial configurations.
18
Widener, Christian A., Dwight A. Burford, and Sarah Jurak. "Effects of Tool Design and Friction Stir Welding Parameters on Weld Morphology in Aluminum Alloys." Materials Science Forum 638-642 (January 2010): 1261–66. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1261.
Full textAbstract:
Friction stir welding (FSW) is a complex thermo-mechanical process which produces wrought microstructure with microstructural gradients in grain size, grain orientation, dislocation density, and precipitate distribution. The type and degree of microstructural modification is a function of the particular alloy chosen, its initial temper, the tool design and corresponding weld process parameter window, and other variables like material thickness, size, fixturing, etc. Since the microstructural changes produced can dramatically affect resultant mechanical performance and corrosion response, a thorough understanding of the variables involved in those changes is needed. A design of experiments approach was used to study the effects of welding parameter selection on the microstructural changes wrought by FSW with two different sizes of the same FSW tool design. A combination of microhardness mapping and electrical conductivity testing was used to investigate potential differences. The importance of these factors and the means for characterizing them for developing standards and specifications are also discussed.
19
Middleton, Dana M., Jonathan Y. Li, Hui J. Lee, Steven Chen, Patricia I. Dickson, N. Matthew Ellinwood, Leonard E. White, and James M. Provenzale. "Diffusion tensor imaging tensor shape analysis for assessment of regional white matter differences." Neuroradiology Journal 30, no. 4 (June 20, 2017): 324–29. http://dx.doi.org/10.1177/1971400917709628.
Full textAbstract:
Purpose The purpose of this study was to investigate a novel tensor shape plot analysis technique of diffusion tensor imaging data as a means to assess microstructural differences in brain tissue. We hypothesized that this technique could distinguish white matter regions with different microstructural compositions. Methods Three normal canines were euthanized at seven weeks old. Their brains were imaged using identical diffusion tensor imaging protocols on a 7T small-animal magnetic resonance imaging system. We examined two white matter regions, the internal capsule and the centrum semiovale, each subdivided into an anterior and posterior region. We placed 100 regions of interest in each of the four brain regions. Eigenvalues for each region of interest triangulated onto tensor shape plots as the weighted average of three shape metrics at the plot's vertices: CS, CL, and CP. Results The distribution of data on the plots for the internal capsule differed markedly from the centrum semiovale data, thus confirming our hypothesis. Furthermore, data for the internal capsule were distributed in a relatively tight cluster, possibly reflecting the compact and parallel nature of its fibers, while data for the centrum semiovale were more widely distributed, consistent with the less compact and often crossing pattern of its fibers. This indicates that the tensor shape plot technique can depict data in similar regions as being alike. Conclusion Tensor shape plots successfully depicted differences in tissue microstructure and reflected the microstructure of individual brain regions. This proof of principle study suggests that if our findings are reproduced in larger samples, including abnormal white matter states, the technique may be useful in assessment of white matter diseases.
20
Raab, Peter, Elke Hattingen, Kea Franz, Friedhelm E. Zanella, and Heinrich Lanfermann. "Cerebral Gliomas: Diffusional Kurtosis Imaging Analysis of Microstructural Differences." Radiology 254, no. 3 (March 2010): 876–81. http://dx.doi.org/10.1148/radiol.09090819.
Full text
21
Wakai, Eiichi, Shuhei Nogami, Akira Hasegawa, Nariaki Okubo, Shigeru Takaya, Takashi Tanno, Yuji Nagae, et al. "Effects of Helium Production and Displacement Damage on Microstructural Evolution and Mechanical Properties in Helium-Implanted Austenitic Stainless Steel and Ferritic/Martensitic Steel." Materials Science Forum 1024 (March 2021): 53–69. http://dx.doi.org/10.4028/www.scientific.net/msf.1024.53.
Full textAbstract:
The effects of helium concentration and displacement damage on microstructural evolution at low dpa and low helium concentration were mainly investigated in specimens of austenitic stainless steel 316FR or SUS304 and a high chromium martensitic steel (HCM12A). The 316FR and HCM12A specimens were implanted uniformly with helium at 823 K up to 30 appm-He or 50 appm-He by 50 MeV cyclotron accelerator using energy degraders. After the helium implantation, the microstructures were examined by a transmission electron microscopy and positron annihilation lifetime measurements. Irradiation hardening behaviors were analyzed using SUS304 and HCM12A steels at 823 K implanted with He ion up to 100 appm with different He/dpa ratios in the HIT ion irradiation experiments and the hardening behaviors were examined by nano indentation method. In the irradiation and annealing specimens, these mechanical properties and microstructures were examined to understand the effects of helium production, displacement damage and annealing on microstructural development, and kinetic Monte Carlo (kMC) simulations were also performed to understand the microstructural development, and the results were compared with the results of TEM observation and positron annihilation lifetime measurements. Important some differences in the microstructural developments such as cavity formation and growth between austenitic stainless steel and martensitic steel were observed in low dpa and low helium concentration conditions.
22
Góral, A., K. Berent, M. Nowak, and B. Kania. "Microstructure and Properties of Ni and Ni/Al2O3 Coatings Electrodeposited at Various Current Densities." Archives of Metallurgy and Materials 61, no. 1 (March 1, 2016): 55–60. http://dx.doi.org/10.1515/amm-2016-0001.
Full textAbstract:
The study presents investigations of an influence of various direct current densities on microstructure, residual stresses, texture, microhardness and corrosion resistance of the nickel coatings electrodeposited from modified Watt’s baths. The properties of obtained coatings were compared to the nano-crystalline composite Ni/Al2O3 coatings prepared under the same plating conditions. The similarities and differences of the obtained coatings microstructures visible on both their surfaces and cross sections and determined properties were presented. The differences in the growth character of the Ni matrix and in the microstructural properties were observed. All electrodeposited Ni and Ni/Al2O3 coatings were compact and well adhering to the steel substrates. The thickness and the microhardness of the Ni and Ni/Al2O3 deposits increased significantly with the current density in the range 2 - 6 A/dm2. Residual stresses are tensile and they reduced as the current density increased. The composite coatings revealed better protection from the corrosion of steel substrate than pure nickel in solution 1 M NaCl.
23
Morga, Rafał, and Barbara Bielowicz. "Raman Spectroscopy of Lignite Gasification Char Morphotypes." Energies 15, no. 16 (August 21, 2022): 6057. http://dx.doi.org/10.3390/en15166057.
Full textAbstract:
The purpose of this study is to characterize and compare the microstructural features of the main morphotypes occurring in the char obtained at 850–950 °C by fluidized bed gasification of lignite from the “Szczerców” deposit (Central Poland), and to bring new insights into the knowledge on the origin of these morphotypes. Optical microscopy and Raman spectroscopy were used. The char is composed mostly of crassinetwork and inertoid, accompanied by tenuinetwork and small amounts of fusinoid. Tenuinetwork originates mainly from textinite, crassinetwork is formed from attrinite, while inertoid results from transformation of strongly gelified macerals such as densinite and ulminite. Similarities in the microstructure of tenuinetwork and crassinetwork as well as inertoid and fusinoid are observed. Inertoid and fusinoid are composed of larger aromatic systems, with lower amount of alkyl-aryl structures, and their microstructure is better organized compared to tenuinetwork and crassinetwork. Inertoid and fusinoid differ in microscopic appearance and were formed from different starting materials, but their microstructural properties converged during gasification. Different morphological features of the network morphotypes (tenuinetwork, crassinetwork) are not reflected in the differences in their microstructural characteristics.
24
Soldatova, S. Yu. "On the issue of assessing the quality of meat of slaughter animals by microstructural methods." Tovaroved prodovolstvennykh tovarov (Commodity specialist of food products), no. 1 (January 1, 2021): 69–72. http://dx.doi.org/10.33920/igt-2101-10.
Full textAbstract:
The article discusses the possibilities of using microstructural methods of analysis to determine the quality of meat, including injected with complex food additives. The results of histological tests of meat are presented, characteristic features and main differences in the microstructure of muscle fibers after repeated defrosting and after treatment with water-retaining additives are determined.
25
Brodarac, Zovko, N. Dolic, and F. Unkic. "Influence of copper content on microstructure development of AlSi9Cu3 alloy." Journal of Mining and Metallurgy, Section B: Metallurgy 50, no. 1 (2014): 53–60. http://dx.doi.org/10.2298/jmmb130125009b.
Full textAbstract:
Microstructure development and possible interaction of present elements have been determined in charge material of EN AlSi9Cu3 quality. Literature review enables prediction of solidification sequence. Modelling of equilibrium phase diagram for examined chemical composition has been performed, which enables determination of equilibrium solidification sequence. Microstructural investigation indicated distribution and morphology of particular phase. Metallographic analysis tools enable exact determination of microstructural constituents: matrix ?Al, eutectic ?Al+?Si, iron base intermetallic phase - Al5FeSi, Alx(Fe,Mn)yCuuSiw and/or Alx(Fe,Mn)yMgzCuuSiw and copper base phases in ternary eutectic morphology Al-Al2Cu-Si and in complex intermetallic ramified morphology Alx(Fe,Mn)yMgzSiuCuw. Microstructure development examination reveals potential differences due to copper content which is prerequisite for high values of final mechanical, physical and technological properties of cast products.
26
Schmoelzer, Thomas, Klaus Dieter Liss, Svea Mayer, Kun Yan, Mark Reid, Rian J. Dippenaar, Matthew J. Peel, and Helmut Clemens. "Hot Deformation of Cast and Extruded TiAl: An In Situ Diffraction Study." Materials Science Forum 706-709 (January 2012): 1725–30. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1725.
Full textAbstract:
Intermetallic TiAl alloys are a class of innovative high-temperature materials which are developed to replace the substantially denser Ni-base alloys in low-pressure turbine blades of jet engines. By streamlining the production process of these parts, a substantial decrease in production costs can be achieved. To this end, a profound knowledge of the microstructural processes occurring during hot deformation is a prerequisite. To investigate the microstructural development during forming operations, cast and extruded as well as only cast specimens were hot-deformed and the microstructural development investigated in-situ by means of a novel diffraction method. This powder diffraction method utilizes the behavior of individual reflection spots on the Debye-Scherrer rings for deriving the materials response to the deformation imposed. It was found that the behavior of the two specimens is rather similar, although the starting microstructures show pronounced differences.
27
Li, Luoyang, Marissa J. Betts, Hao Yun, Bing Pan, Timothy P. Topper, Guoxiang Li, Xingliang Zhang, and Christian B. Skovsted. "Fibrous or Prismatic? A Comparison of the Lamello-Fibrillar Nacre in Early Cambrian and Modern Lophotrochozoans." Biology 12, no. 1 (January 11, 2023): 113. http://dx.doi.org/10.3390/biology12010113.
Full textAbstract:
The Precambrian–Cambrian interval saw the first appearance of disparate modern metazoan phyla equipped with a wide array of mineralized exo- and endo-skeletons. However, the current knowledge of this remarkable metazoan skeletonization bio-event and its environmental interactions is limited because uncertainties have persisted in determining the mineralogy, microstructure, and hierarchical complexity of these earliest animal skeletons. This study characterizes in detail a previously poorly understood fibrous microstructure—the lamello-fibrillar (LF) nacre—in early Cambrian mollusk and hyolith shells and compares it with shell microstructures in modern counterparts (coleoid cuttlebones and serpulid tubes). This comparative study highlights key differences in the LF nacre amongst different lophotrochozoan groups in terms of mineralogical compositions and architectural organization of crystals. The results demonstrate that the LF nacre is a microstructural motif confined to the Mollusca. This study demonstrates that similar fibrous microstructure in Cambrian mollusks and hyoliths actually represent a primitive type of prismatic microstructure constituted of calcitic prisms. Revision of these fibrous microstructures in Cambrian fossils demonstrates that calcitic shells are prevalent in the so-called aragonite sea of the earliest Cambrian. This has important implications for understanding the relationship between seawater chemistry and skeletal mineralogy at the time when skeletons were first acquired by early lophotrochozoan biomineralizers.
28
Yu, Peiqiang, Colleen R. Christensen, David A. Christensen, and John J. McKinnon. "Ultrastructural-chemical makeup of yellow-seeded (Brassica rapa) and brown-seeded (Brassica napus) canola within cellular dimensions, explored with synchrotron reflection FTIR microspectroscopy." Canadian Journal of Plant Science 85, no. 3 (July 1, 2005): 533–41. http://dx.doi.org/10.4141/p04-080.
Full textAbstract:
Synchrotron-based FTIR micro spectroscopy, developed recently as a novel, rapid and non-destructive analytical technique, could reveal chemical information of the intrinsic microstructures of biological tissues at ultra-spatial resolution. The objective of this study was to use synchrotron reflection FTIR microspectroscopy to explore chemical makeup (functional group and bonding characteristics) of ultrastructural tissues within cellular dimensions (10 µm × 10 µm) of yellow-seeded (Brassica rapa ‘Klondike’) and brown-seeded (Brassica napus ‘Bounty’) canola. The results showed that the ratios of total CH2:CH3, CH3-asymmetric:CH3-symmetric, CH2-asymmetric:CH2-symmetric and total CH-asymmetric:CH-symmetric were 1.06 and 1.13, 1.28 and 1.26, 2.90 and 3.08, 1.82 and 1.78, for the yellow-seeded and brown-seeded canola, respectively. There were no differences between the two canola types in the content and ratios of CH groups (CH2 and CH3) of the scanned areas, indicating that lipid chain length and branching are similar between the two seed types. There were significant differences in amide I and total CHO, indicating different microstructural protein (peptide C=O bonding) and carbohydrate makeup between the two canola types. The results also show differences in the ratios of total NH and OH:CHO (2.85 vs. 3.84, P < 0.01), total CH:total CHO (0.23 vs. 0.32, P < 0.01), amide I:NH and OH (0.48 vs. 0.37, P = 0.07), amide I:hemiceullulose (P = 0.09), hemicellulose:total CHO (0.039 vs. 0.059, P < 0.001), CHO:amide I (1.11 vs. 0.84, P = 0.051) between the yellow-seeded and brown-seeded canola, and indicate that the chemical makeup of the microstructure differs between the yellow-seeded (Brassica rapa) and brown-seeded (Brassica napus) canola type. In conclusion, this study indicates that synchrotron-based reflection FTIR microspectroscopy can be used to identify microstructural-chemical features of canola tissue. More detailed study is required to define the extent of differences that exist between the yellow-seeded (Brassica rapa) vs. dark-brownseeded (Brassica napus) canola. Such information on the microstructural-chemical features can be used by canola breeding programs to select superior varieties of canola for special purposes, and for predicting canola quality and nutritive value for humans and animals. Key words: Synchrotron, reflection infrared microspectroscopy, functional groups, chemical makeup, ultrastructure, canola, feed structure and chemistry
29
Zhu, H., Dong Yi Seo, and Kouichi Maruyama. "Effect of Heat Treatment on Microstructure and Mechanical Property of 45XD and 47XD TiAl Alloys." Materials Science Forum 475-479 (January 2005): 581–84. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.581.
Full textAbstract:
The effect of heat treatment on microstructure and property of Ti-45 and 47Al-2Nb-2Mn+0.8%vol.%TiB2 alloys (45XD and 47XD) has been studied. Annealing and subsequent oil quench produced fine-grained fully lamellar structure (FGFL) in both alloys. For microstructural stabilization, the FGFL structures were subjected to different aging treatments. Microstructural examination showed that degradation of the FGFL structure, such as coarsening of γ lamellae, recrystallization of γ grains and break-up of a2 lamellae, presented to varying degrees after different aging treatments. Hardness values in the aged alloys decreased due to the degradation. The creep resistances were improved in the aged alloys though the degradation occurred, indicating that the aging treatments stabilized the FGFL structures effectively. The differences in the changes of properties caused by different aging treatments and compositions were compared in combination with the microstructural variants.
30
Mohr, Gunther, Konstantin Sommer, Tim Knobloch, Simon J. Altenburg, Sebastian Recknagel, Dirk Bettge, and Kai Hilgenberg. "Process Induced Preheating in Laser Powder Bed Fusion Monitored by Thermography and Its Influence on the Microstructure of 316L Stainless Steel Parts." Metals 11, no. 7 (July 1, 2021): 1063. http://dx.doi.org/10.3390/met11071063.
Full textAbstract:
Undetected and undesired microstructural variations in components produced by laser powder bed fusion are a major challenge, especially for safety-critical components. In this study, an in-depth analysis of the microstructural features of 316L specimens produced by laser powder bed fusion at different levels of volumetric energy density and different levels of inter layer time is reported. The study has been conducted on specimens with an application relevant build height (>100 mm). Furthermore, the evolution of the intrinsic preheating temperature during the build-up of specimens was monitored using a thermographic in-situ monitoring set-up. By applying recently determined emissivity values of 316L powder layers, real temperatures could be quantified. Heat accumulation led to preheating temperatures of up to about 600 °C. Significant differences in the preheating temperatures were discussed with respect to the individual process parameter combinations, including the build height. A strong effect of the inter layer time on the heat accumulation was observed. A shorter inter layer time resulted in an increase of the preheating temperature by more than a factor of 2 in the upper part of the specimens compared to longer inter layer times. This, in turn, resulted in heterogeneity of the microstructure and differences in material properties within individual specimens. The resulting differences in the microstructure were analyzed using electron back scatter diffraction and scanning electron microscopy. Results from chemical analysis as well as electron back scatter diffraction measurements indicated stable conditions in terms of chemical alloy composition and austenite phase content for the used set of parameter combinations. However, an increase of the average grain size by more than a factor of 2.5 could be revealed within individual specimens. Additionally, differences in feature size of the solidification cellular substructure were examined and a trend of increasing cell sizes was observed. This trend was attributed to differences in solidification rate and thermal gradients induced by differences in scanning velocity and preheating temperature. A change of the thermal history due to intrinsic preheating could be identified as the main cause of this heterogeneity. It was induced by critical combinations of the energy input and differences in heat transfer conditions by variations of the inter layer time. The microstructural variations were directly correlated to differences in hardness.
31
Nzogang, Billy Clitton, Manuel Thieme, Alexandre Mussi, Sylvie Demouchy, and Patrick Cordier. "Characterization of recovery onset by subgrain and grain boundary migration in experimentally deformed polycrystalline olivine." European Journal of Mineralogy 32, no. 1 (January 15, 2020): 13–26. http://dx.doi.org/10.5194/ejm-32-13-2020.
Full textAbstract:
Abstract. To apprehend plate tectonics and the dynamics of the lithosphere–asthenosphere boundary, composed principally of olivine, we need to understand the mechanisms that control plastic deformation of olivine in the relevant temperature domain. After more than 50 years of laboratory studies and investigations on natural rocks, the interplay of several key parameters (e.g. temperature, pressure, vacancy concentration, dislocation densities, grain size, strain rate) controlling polycrystalline olivine plasticity remains difficult to assess. Here, we study four olivine polycrystals, which have been deformed in axial compression under a confining pressure of 300 MPa, at 1273 or 1473 K. Despite significant differences in mechanical properties (stress–strain curves), previous characterization by scanning (SEM) and transmission electron microscopy (TEM) did not reveal significant differences in dislocation microstructures which could explain these contrasted behaviours. We have undertaken automatic crystallographic orientation mapping (ACOM) analyses in TEM to increase the spatial resolution of characterization compared to previously obtained electron backscatter diffraction maps to further decipher the microstructures at nanoscale. With this novel technique applied to olivine, a noticeable difference in the onset of microstructural recovery has been identified between specimens deformed at 1273 and 1473 K. The microstructures of the olivine polycrystals deformed at 1473 K exhibit numerous curved grain and subgrain boundaries, advocating for recovery by boundary migration. In contrast, the microstructures of the olivine polycrystals deformed at 1273 K have significantly fewer subgrain boundaries and show more straight boundaries (i.e. closer to an equilibrium microstructure) than in the specimen deformed at 1473 K. Characterization by ACOM-TEM has permitted the identification of the onset of recovery, which is led by boundary migration even for very low macroscopic finite strains.
32
Green, Tamar, Naama Barnea-Goraly, Mira Raman, Scott S. Hall, Amy A. Lightbody, Jennifer L. Bruno, Eve-Marie Quintin, and Allan L. Reiss. "Specific effect of the fragile-X mental retardation-1 gene (FMR1) on white matter microstructure." British Journal of Psychiatry 207, no. 2 (August 2015): 143–48. http://dx.doi.org/10.1192/bjp.bp.114.151654.
Full textAbstract:
BackgroundFragile-X syndrome (FXS) is a neurodevelopmental disorder associated with intellectual disability and neurobiological abnormalities including white matter microstructural differences. White matter differences have been found relative to neurotypical individuals.AimsTo examine whether FXS white matter differences are related specifically to FXS or more generally to the presence of intellectual disability.MethodWe used voxel-based and tract-based analytic approaches to compare individuals with FXS (n = 40) with gender- and IQ-matched controls (n = 30).ResultsIndividuals with FXS had increased fractional anisotropy and decreased radial diffusivity values compared with IQ-matched controls in the inferior longitudinal, inferior fronto-occipital and uncinate fasciculi.ConclusionsThe genetic variation associated with FXS affects white matter microstructure independently of overall IQ. White matter differences, found in FXS relative to IQ-matched controls, are distinct from reported differences relative to neurotypical controls. This underscores the need to consider cognitive ability differences when investigating white matter microstructure in neurodevelopmental disorders.
33
Duijsens, Dorine, Sarah H. E. Verkempinck, Audrey De Coster, Katharina Pälchen, Marc Hendrickx, and Tara Grauwet. "How Cooking Time Affects In Vitro Starch and Protein Digestibility of Whole Cooked Lentil Seeds versus Isolated Cotyledon Cells." Foods 12, no. 3 (January 24, 2023): 525. http://dx.doi.org/10.3390/foods12030525.
Full textAbstract:
Lentils are sustainable sources of bioencapsulated macronutrients, meaning physical barriers hinder the permeation of digestive enzymes into cotyledon cells, slowing down macronutrient digestion. While lentils are typically consumed as cooked seeds, insights into the effect of cooking time on microstructural and related digestive properties are lacking. Therefore, the effect of cooking time (15, 30, or 60 min) on in vitro amylolysis and proteolysis kinetics of lentil seeds (CL) and an important microstructural fraction, i.e., cotyledon cells isolated thereof (ICC), were studied. For ICC, cooking time had no significant effect on amylolysis kinetics, while small but significant differences in proteolysis were observed (p < 0.05). In contrast, cooking time importantly affected the microstructure obtained upon the mechanical disintegration of whole lentils, resulting in significantly different digestion kinetics. Upon long cooking times (60 min), digestion kinetics approached those of ICC since mechanical disintegration yielded a high fraction of individual cotyledon cells (67 g/100 g dry matter). However, cooked lentils with a short cooking time (15 min) showed significantly slower amylolysis with a lower final extent (~30%), due to the presence of more cell clusters upon disintegration. In conclusion, cooking time can be used to obtain distinct microstructures and digestive functionalities with perspectives for household and industrial preparation.
34
Yazici, Ziya Ozgur. "Effect of vacuum conditions on stability and crystallization of cobalt based amorphous alloy." Materials Science-Poland 38, no. 1 (March 1, 2020): 181–88. http://dx.doi.org/10.2478/msp-2020-0003.
Full textAbstract:
AbstractThe aim of this work was to investigate the effects of moderate vacuum conditions (10 Pa, 1 × 103 Pa and 2 × 104 Pa) on glass forming ability, thermal stability and aging behavior of Co42Cu1Fe20Ta5:5B26:5Si5 amorphous samples in terms of size and distribution of crystalline precipitates. The thinnest parts (300 μm) of the wedge-shaped samples were amorphous for all vacuum conditions, and they had similar compositional, structural and thermal characteristics. However, they represented different microstructural features after heat treatments at 950 K and 1100 K. The same phases precipitated in all samples but the amount and the size of the precipitates increased as the pressure was raised to the normal atmospheric value. The differences in the glass forming ability and the microstructure due to aging are considered to originate from lower thermal characteristics, such as relaxation and reduced glass temperature as well as γ parameter, resulting from the poor vacuum pressure used in the production process. The differences in the microstructures and hardness values caused by heat treatments have been observed.
35
Peterson, Paul?D, and Deanne?J Idar. "Microstructural Differences between Virgin and Recycled Lots of PBX 9502." Propellants, Explosives, Pyrotechnics 30, no. 2 (April 2005): 88–94. http://dx.doi.org/10.1002/prep.200400088.
Full text
36
Ogiso, Makoto, Yasuo Yamashita, and Toshio Matsumoto. "Differences in microstructural characteristics of dense HA and HA coating." Journal of Biomedical Materials Research 41, no. 2 (August 1998): 296–303. http://dx.doi.org/10.1002/(sici)1097-4636(199808)41:2<296::aid-jbm15>3.0.co;2-j.
Full text
37
Houston, James R., Michelle L. Hughes, Ilana J. Bennett, Philip A. Allen, Jeffrey M. Rogers, Mei-Ching Lien, Haylie Stoltz, et al. "Evidence of Neural Microstructure Abnormalities in Type I Chiari Malformation: Associations Among Fiber Tract Integrity, Pain, and Cognitive Dysfunction." Pain Medicine 21, no. 10 (May 10, 2020): 2323–35. http://dx.doi.org/10.1093/pm/pnaa094.
Full textAbstract:
Abstract Background Previous case–control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known. Methods Eighteen female CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group. Results CMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group. Conclusions Diffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.
38
Chlup, Zdeněk, Stanislava Fintová, Hynek Hadraba, Ivo Kuběna, Monika Vilémová, and Jiří Matějíček. "Fatigue Behaviour and Crack Initiation in CoCrFeNiMn High-Entropy Alloy Processed by Powder Metallurgy." Metals 9, no. 10 (October 17, 2019): 1110. http://dx.doi.org/10.3390/met9101110.
Full textAbstract:
Single-phase equiatomic five-element high entropy alloy CoCrFeMnNi was prepared by powder metallurgy. Two materials with ultra-fine-grained microstructure were prepared by spark plasma sintering (SPS) of ball-milled powder at two sintering times (5 and 10 min), assigned as HEA 5 and HEA 10, respectively. Basic microstructural and mechanical properties were evaluated. The median grain size of the microstructures was determined to be 0.4 and 0.6 μm for HEA 5 and HEA 10, respectively. The differences in the microstructure led to a significant change in strength and deformation characteristics evaluated at room temperature. The effect of cyclic loading was monitored by three-point bending fatigue test. The results show that even relatively small change in the microstructure causes a significant effect on fatigue life. The fatigue endurance limit was measured to be 1100 MPa and 1000 MPa for HEA 5 and HEA 10, respectively. The detailed fractographic analysis revealed that abnormally large grains, localised in the microstructure on the tensile loaded surface, were a typical fatigue initiation site. The formation of (nano) twins together with dislocation slips caused the crack nucleation because of the cyclic loading.
39
Maury, Nicolas, Moukrane Dehmas, Claude Archambeau-Mirguet, Jérôme Delfosse, and Elisabeth Aeby-Gautier. "MICROSTRUCTURAL EVOLUTIONS AND MECHANICAL PROPERTIES DURING LONG-TERM AGEING OF TITANIUM ALLOY Ti-17." MATEC Web of Conferences 321 (2020): 12004. http://dx.doi.org/10.1051/matecconf/202032112004.
Full textAbstract:
Microstructural evolutions and resulting mechanical properties have been investigated in the near-β Ti-17 alloy following long- term ageing heat-treatment up to 6000 h at 450 °C. The initial microstructure was bimodal lamellar, consisting of two populations of α grains (αlam-primary and αsecondary) in a β phase matrix. Two microstructures were obtained either via controlled heat- treatments from the β phase field - in order to generate significant differences in the grain fraction, size, density and spatial distribution - or sampled from a part submitted to an industrial processing route. High energy XRD reveals that whatever the initial microstructure, the amount of α phase increases significantly after 1000 h long-term ageing. Complementary SEM and image analysis characterizations enable to deduce that this evolution is the consequence of αsecondary growth and/or coarsening. Also, TEM observations and EDX analysis show that the Mo and Cr contents of the β phase increase and that α2 nano-precipitates form within the αlam-primary grains. Considering the mechanical properties, long-term ageing leads to an increase in the yield and ultimate tensile strength, as well as a decrease in the elongation at failure, at an extent which depends on the ageing time.
40
Alavi, S. Hamed, Aditi Sinha, Earl Steward, Jeffrey C. Milliken, and Arash Kheradvar. "Load-dependent extracellular matrix organization in atrioventricular heart valves: differences and similarities." American Journal of Physiology-Heart and Circulatory Physiology 309, no. 2 (July 15, 2015): H276—H284. http://dx.doi.org/10.1152/ajpheart.00164.2015.
Full textAbstract:
The extracellular matrix of the atrioventricular (AV) valves' leaflets has a key role in the ability of these valves to properly remodel in response to constantly varying physiological loads. While the loading on mitral and tricuspid valves is significantly different, no information is available on how collagen fibers change their orientation in response to these loads. This study delineates the effect of physiological loading on AV valves' leaflets microstructures using Second Harmonic Generation (SHG) microscopy. Fresh natural porcine tricuspid and mitral valves' leaflets ( n = 12/valve type) were cut and prepared for the experiments. Histology and immunohistochemistry were performed to compare the microstructural differences between the valves. The specimens were imaged live during the relaxed, loading, and unloading phases using SHG microscopy. The images were analyzed with Fourier decomposition to mathematically seek changes in collagen fiber orientation. Despite the similarities in both AV valves as seen in the histology and immunohistochemistry data, the microstructural arrangement, especially the collagen fiber distribution and orientation in the stress-free condition, were found to be different. Uniaxial loading was dependent on the arrangement of the fibers in their relaxed mode, which led the fibers to reorient in-line with the load throughout the depth of the mitral leaflet but only to reorient in-line with the load in deeper layers of the tricuspid leaflet. Biaxial loading arranged the fibers in between the two principal axes of the stresses independently from their relaxed states. Unlike previous findings, this study concludes that the AV valves' three-dimensional extracellular fiber arrangement is significantly different in their stress-free and uniaxially loaded states; however, fiber rearrangement in response to the biaxial loading remains similar.
41
Kim, Joo Han, and Paul H. Holloway. "Microstructural differences in thin film ZnGa2O4:Mn phosphor produced by differences in sputtering gas pressure." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 24, no. 6 (November 2006): 2164–71. http://dx.doi.org/10.1116/1.2359737.
Full text
42
Bueno, S., and Carmen Baudín. "Flaw Tolerant Ceramic Laminates with Negligible Residual Stresses between Layers." Key Engineering Materials 333 (March 2007): 17–26. http://dx.doi.org/10.4028/www.scientific.net/kem.333.17.
Full textAbstract:
Ceramic laminates can be designed to combine high strength with flaw tolerance. In this paper, the designing approach based on the mechanical response of residual stresses free biological layered structures is revised. The main design tools are analysed and different ceramic-ceramic systems combining stiffness, high strength and flaw tolerance with thermo-mechanical stability are described. Two main approaches have been used depending on the relative toughness of the layers and the interfaces between them. Laminates constituted by layers separated by weak interfaces, to originate crack deflection and delamination along the interface, show high thermal shock resistance but limited resistance to shear stresses and, thus, to wear. Laminates with strong interfaces that combine stiff and high strength external layers with flaw tolerant internal ones are appropriate for wear applications. In this group of materials, the combination of layers with the same phase composition and different microstructures avoids residual stresses due to thermal expansion mismatch, but the attainment of such microstructural differences implies the co-sintering of layers with large differences in the green state. The generation “in situ” during sintering of the desired microstructural differences represents an interesting alternative in terms of processing for this group of materials.
43
Košutar, Sara, Matea Kramarić, and Gordana Hržica. "The relationship between narrative microstructure and macrostructure: Differences between six- and eight-year-olds." Psychology of Language and Communication 26, no. 1 (January 1, 2022): 126–53. http://dx.doi.org/10.2478/plc-2022-0007.
Full textAbstract:
Abstract The current study aimed to investigate age-related differences in narrative abilities at the macrostructural and microstructural levels and to examine which microstructural aspects explain narrative macrostructure at ages six and eight. Oral narratives were elicited from 89 Croatian monolingual children using the Multilingual Assessment Instrument for Narratives (MAIN). At the microstructural level, the measure of lexical diversity D, clausal density, and mean length of clause were assessed. Macrostructure was assessed using the standardized MAIN scoring procedure. We found differences between the two age groups in lexical diversity, clausal density, and macrostructure, with eight-year-olds scoring higher on all measures. Variance in the macrostructure was explained to a significant extent by lexical diversity in the case of six-year-olds, and by both lexical diversity and clausal density in the case of eight-year-olds. Our results suggest that six-year-olds rely mostly on lexical abilities when telling a story, while eight-year-olds also draw on syntactic abilities.
44
Shi, Yueqi, Changhong Li, and Dayu Long. "Study of the Microstructure Characteristics of Three Different Fine-grained Tailings Sand Samples during Penetration." Materials 13, no. 7 (March 30, 2020): 1585. http://dx.doi.org/10.3390/ma13071585.
Full textAbstract:
This paper explores the microstructural evolution characteristics of tailings sand samples of different types of infiltration failure during the infiltration failure process. The homemade small infiltration deformation instrument is used to test the infiltration failure characteristics of the tailings sand during the infiltration failure process. Evolutionary characteristics of the internal microstructure pores and particle distribution were also studied. Using CT (computerized tomography) technology to establish digital image information, the distribution of the microscopic characteristics of the particle distribution and pore structure after tailing sand infiltration were studied. Microscopic analysis was also performed to analyze the microscopic process of infiltration and destruction, as well as to see the microscopic structural characteristics of the infiltration and destruction of the total tailings. The test results show that there are obvious differences in the microstructure characterization of fluid soil and piping-type infiltration failures. Microstructure parameters have a certain functional relationship with macrofactors. Combining the relationship between macrophysical and mechanical parameters and microstructural parameters, new ideas for future research and the prevention of tailings sand infiltration and failure mechanisms is provided.
45
Koshiyama, Daisuke, Masaki Fukunaga, Naohiro Okada, Kentaro Morita, Kiyotaka Nemoto, Kaori Usui, Hidenaga Yamamori, et al. "White matter microstructural alterations across four major psychiatric disorders: mega-analysis study in 2937 individuals." Molecular Psychiatry 25, no. 4 (November 29, 2019): 883–95. http://dx.doi.org/10.1038/s41380-019-0553-7.
Full textAbstract:
AbstractIdentifying both the commonalities and differences in brain structures among psychiatric disorders is important for understanding the pathophysiology. Recently, the ENIGMA-Schizophrenia DTI Working Group performed a large-scale meta-analysis and reported widespread white matter microstructural alterations in schizophrenia; however, no similar cross-disorder study has been carried out to date. Here, we conducted mega-analyses comparing white matter microstructural differences between healthy comparison subjects (HCS; N = 1506) and patients with schizophrenia (N = 696), bipolar disorder (N = 211), autism spectrum disorder (N = 126), or major depressive disorder (N = 398; total N = 2937 from 12 sites). In comparison with HCS, we found that schizophrenia, bipolar disorder, and autism spectrum disorder share similar white matter microstructural differences in the body of the corpus callosum; schizophrenia and bipolar disorder featured comparable changes in the limbic system, such as the fornix and cingulum. By comparison, alterations in tracts connecting neocortical areas, such as the uncinate fasciculus, were observed only in schizophrenia. No significant difference was found in major depressive disorder. In a direct comparison between schizophrenia and bipolar disorder, there were no significant differences. Significant differences between schizophrenia/bipolar disorder and major depressive disorder were found in the limbic system, which were similar to the differences in schizophrenia and bipolar disorder relative to HCS. While schizophrenia and bipolar disorder may have similar pathological characteristics, the biological characteristics of major depressive disorder may be close to those of HCS. Our findings provide insights into nosology and encourage further investigations of shared and unique pathophysiology of psychiatric disorders.
46
Katti, Kalpana S., Maoxu Qian, Daniel W. Frech, and Mehmet Sarikaya. "Low-loss Electron Energy-loss Spectroscopy and Dielectric Function of Biological and Geological Polymorphs of CaCO3." Microscopy and Microanalysis 5, no. 5 (September 1999): 358–64. http://dx.doi.org/10.1017/s1431927699000197.
Full textAbstract:
Previous work on microstructural characterization has shown variations in terms of defects and organization of nanostructures in the two polymorphs of calcium carbonate, calcite, and aragonite in mollusc shells. Large variations in mechanical properties are observed between these sections which have been attributed to variations in composite microstructure as well as intrinsic properties of the inorganic phases. Here we present local low-loss electron energy-loss spectroscopic (EELS) study of calcitic and aragonitic regions of abalone shell that were compared to geological (single-crystal) counterpart polymorphs to reveal intrinsic differences that could be related to organismal effects in biomineralization. In both sets of samples, local dielectric function is computed using Kramer-Kronig analysis. The electronic structures of biogenic and geological calcitic materials are not significantly different. On the other hand, electronic structure of biogenic aragonite is remarkably different from that of geological aragonite. This difference is attributed to the increased contribution from single electron excitations in biogenic aragonite as compared to that of geological aragonite. Implications of these changes are discussed in the context of macromolecular involvement in the making of the microstructures and properties in biogenic phases.
47
Morales-Rivas, Lucia, Hans Roelofs, Stephan Hasler, Carlos García-Mateo, and Francisca García Caballero. "Complex Microstructural Banding of Continuously Cooled Carbide-Free Bainitic Steels." Materials Science Forum 783-786 (May 2014): 980–85. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.980.
Full textAbstract:
Chemical segregation of alloying elements during solidification of steel grades leads to development of a banded microstructure, causing a degree of anisotropy that can be detrimental to the mechanical behavior under service conditions. It is well-known that the presence of strongly orientated martensite bands in carbide-free bainitic microstructures, associated to inhomogeneous Mn redistribution during solidification, leads to a remarkable deterioration in toughness in advanced high strength bainitic steels. In this study, while bands were clearly visible on light optical micrographs of continuously cooled carbide-free bainitic steels, scanning electron microscopy examination revealed only a gradual transition between matrix and bands, both with a granular bainitic structure. Electron backscatter diffraction was used to quantify the bainitic packet size and volume fraction of martensite/austenite constituent between and within the bands, after a process of optimization of the analysis settings in order to minimize the inherent difficulties linked to sub-micrometric and minority phase indexation. The quantitative microstructural results showed negligible morphological differences between bainitic structure bands and matrix, only solute segregation of Cr and Mo was detected by energy-dispersive X-ray spectroscopy within bands, which must be responsible for a stronger resistance against metallographic etching in those regions.
48
Dimitrova, Ralica, Maximilian Pietsch, Daan Christiaens, Judit Ciarrusta, Thomas Wolfers, Dafnis Batalle, Emer Hughes, et al. "Heterogeneity in Brain Microstructural Development Following Preterm Birth." Cerebral Cortex 30, no. 9 (April 18, 2020): 4800–4810. http://dx.doi.org/10.1093/cercor/bhaa069.
Full textAbstract:
Abstract Preterm-born children are at increased risk of lifelong neurodevelopmental difficulties. Group-wise analyses of magnetic resonance imaging show many differences between preterm- and term-born infants but do not reliably predict neurocognitive prognosis for individual infants. This might be due to the unrecognized heterogeneity of cerebral injury within the preterm group. This study aimed to determine whether atypical brain microstructural development following preterm birth is significantly variable between infants. Using Gaussian process regression, a technique that allows a single-individual inference, we characterized typical variation of brain microstructure using maps of fractional anisotropy and mean diffusivity in a sample of 270 term-born neonates. Then, we compared 82 preterm infants to these normative values to identify brain regions with atypical microstructure and relate observed deviations to degree of prematurity and neurocognition at 18 months. Preterm infants showed strikingly heterogeneous deviations from typical development, with little spatial overlap between infants. Greater and more extensive deviations, captured by a whole brain atypicality index, were associated with more extreme prematurity and predicted poorer cognitive and language abilities at 18 months. Brain microstructural development after preterm birth is highly variable between individual infants. This poorly understood heterogeneity likely relates to both the etiology and prognosis of brain injury.
49
Gavras, Anastasios, Anthony Spangenberger, and Diana A. Lados. "Fatigue Crack Growth in Cast and Wrought Aluminium Alloys." Materials Science Forum 765 (July 2013): 574–79. http://dx.doi.org/10.4028/www.scientific.net/msf.765.574.
Full textAbstract:
Fatigue crack growth (FCG) behaviour of cast aluminium alloys with different strengthening mechanisms (A535, 319, A356, A390) and wrought aluminium alloys (6061) was investigated in this study. Among the various parameters that can affect the propagation of fatigue cracks, the initial flaw size and microstructure were studied and correlated. Long and small FCG tests at low and high positive stress ratios were conducted on these materials in room temperature air. The mechanisms of FCG at the microstructural scale were identified and will be compared and discussed. In addition, two-parameter design diagrams were constructed to link loading conditions to microstructural response and fracture modes determined from fractographic observations. Finally, a new methodology and tools that can be used to bridge the differences between small and long fatigue cracks were developed and will be presented.
50
Felker, Caleb A., John G. Speer, Emmanuel De Moor, and Kip O. Findley. "Hot Strip Mill Processing Simulations on a Ti-Mo Microalloyed Steel Using Hot Torsion Testing." Metals 10, no. 3 (March 3, 2020): 334. http://dx.doi.org/10.3390/met10030334.
Full textAbstract:
Precipitation strengthened, fully ferritic microstructures in low-carbon, microalloyed steels are used in applications requiring enhanced stretch-flange formability. This work assesses the influence of thermomechanical processing on the evolution of austenite and the associated final ferritic microstructures. Hot strip mill processing simulations were performed on a low-carbon, titanium-molybdenum microalloyed steel using hot torsion testing to investigate the effects of extensive differences in austenite strain accumulation on austenite morphology and microstructural development after isothermal transformation. The gradient of imposed shear strain with respect to radial position inherent to torsion testing was utilized to explore the influence of strain on microstructural development for a given simulation, and a tangential cross-section technique was employed to quantify the amount of shear strain that accumulated within the austenite during testing. Greater austenite shear strain accumulation resulted in greater refinement of both the prior austenite and polygonal ferrite grain sizes. Further, polygonal ferrite grain diameter distributions were narrowed, and the presence of hard, secondary phase constituents was minimized, with greater amounts of austenite strain accumulation. The results indicate that extensive austenite strain accumulation before decomposition is required to achieve desirable, ferritic microstructures.