Journal articles: 'Lamellar'

1

Zhuravlev, A. V. "Composition, structure and model of the formation of conodont lamellar tissue." LITHOSPHERE (Russia) 20, no. 2 (April 25, 2020): 184–95. http://dx.doi.org/10.24930/1681-9004-2020-20-2-184-195.

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Research subject. This research was focused on the most common mineralized tissue that composes conodont elements. The aim was to investigate the characteristics of the composition and structure of this tissue and to reconstruct its formation process. Materials and methods. The work was based on a collection of well-preserved conodont elements from the Upper Devonian of the East European Platform and the Upper Devonian – Lower Carboniferous of the east of the Pechora Plate. Oriented and polished thin sections made from some of the elements were studied using light and electron microscopy, as well as a microhardness tester. Energy dispersive spectroscopy was used to determine the chemical (elemental) composition of the lamellar tissue. In addition, the carbon isotope ratio was determined for organic matter. Results. The study showed that the lamellar tissue in conodont elements consists of fluorohydroxylapatite crystallites of various morphology, surrounded by organic matter, which makes up 2–3% of the tissue. Variations in the composition of major elements incorporated in fluorohydroxylapatite of the lamellar tissue are insignificant. Organic matter is represented by a collagen-like protein, likely to be of a non-fibrillar type, with a light carbon isotopic composition (–26.2 ‰ PDB). The lamellar tissue has an average microhardness of 2.6 GPa, the variations of which are due to textural and structural features and the distribution of organic matter. In conodont elements, the lamellar tissue is in contact with other types of tissue. Transitions between tissues are relatively sharp at the borders of the lamellae and gradual within the same lamella. Conclusions. A model was developed, according to which the growth cycle of a conodont element covered the sequential formation of two lamellae preceded by the resorption of one external lamella. In the structures formed by the lamellar tissue, both lamellae consisted of this tissue. The lamellar tissue is of interest as a natural model of an organic-mineral composite based on protein and calcium phosphate.

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Chang, Xia, Xiao Bin Zhang, and Ji Zhang. "Effect of Heat Treatment and Composition on Grain Size and Lamellar Spacing of a Lamellar TiAl Alloy." Advanced Materials Research 335-336 (September 2011): 774–78. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.774.

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The article presents the results of optical microscopy, scanning electron microscopy (SEM), Transmission Electron Microscope (TEM) conducted on a Ti–46.5Al–2.5V-1.0Cr–0.3Ni alloy before and after different heat treatments. Heat treatment of the alloy at 1340°C followed by cooling leads to the formation of the fully lamellar microstructure which consists of γ lamellae mostly and of small amount of α2 lamellae. The cooling rate of 50°C/min in alloy tcx1-G produced an optimal microstructure. This cooling rate generated finest lamellae with the smallest individual lamella spacing among the alloys.

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Dey, Sudip, Utpal Rajguru, Dinesh Chandra Pathak, and Umesh C. Goswami. "Analysis of Gill Structure from a Fresh Water Fish (Heteropneustes fossilis) Exposed to Bleached Sulfite Pulp Mill Effluents." Microscopy and Microanalysis 21, no. 2 (March 23, 2015): 385–91. http://dx.doi.org/10.1017/s1431927615000045.

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AbstractThe present communication reports toxic effects of bleached sulfite pulp mill effluents in fish (Heteropneustes fossilis) gills, with optical, scanning electron, and transmission electron microscopy. The general adverse effects include dilation of the primary lamellar wall, curling of secondary lamellar terminals, displacement of epithelial cell layers, degeneration of secondary lamella, deposition of mucous, and severe congestion in the gill arch. The significant shortening of secondary lamellae, widening of lamellar tips, and significant decrease in the number of mitochondria in chloride cells as compared to controls are some specific effects of bleached sulfite pulp mill effluents. Scanning electron microscopy demonstrated tearing of tissues in gill lamellae and arches. Transmission electron microscopy revealed membrane distortion of mitochondria in chloride cells, loss of uniformity of microvilli in pavement cells, and abnormalities in nuclear shape in different cells of effluent-exposed fish gills. Toxicity of the bleached sulfite pulp mill effluents and its impact on fish are discussed in the light of existing literature. Further, the importance of microscopy in toxicological evaluation of environmental pollutants is emphasized in view of its specific application potential.

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Gao, Ka, Zan Zhang, Junliang Zhao, Dejian Sun, and Fu Wang. "Orientation and Microstructure Evolution of Al-Al2Cu Regular Eutectic Lamellar Bifurcating in an Abruptly Changing Velocity under Directional Solidification." Materials 13, no. 4 (February 24, 2020): 1004. http://dx.doi.org/10.3390/ma13041004.

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In an abruptly changing velocity under directional solidification, microstructures and the growth orientation of Al-Al2Cu eutectic lamellar were characterized. The change in solidification rate led to an interfacial instability, which results in a bifurcation of the eutectic lamella into new, refined lamellae. The growth orientation of the eutectic Al2Cu phase was also only in its (001) direction and more strongly oriented to the heat flow direction. The results suggest that the eutectic lamellar Al-Al2Cu bifurcation and the spacing adjustment may be caused by the rate determining lateral diffusion of the solutes after interfacial instability.

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Cui, Ning, Qianqian Wu, Jin Wang, Binjiang Lv, and Fantao Kong. "The Directional Solidification, Microstructural Characterization and Deformation Behavior of β-Solidifying TiAl Alloy." Materials 12, no. 8 (April 12, 2019): 1203. http://dx.doi.org/10.3390/ma12081203.

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A β-solidifying Ti–43Al–2Cr–2Mn–0.2Y alloy was directionally solidified by the optical floating zone melting method. The microstructure is mainly characterized by γ/α2 lamellae with specific orientations, which exhibits straight boundaries. The β phase is randomly distributed in the lamellar microstructure, indicating that the β phase cannot be directionally solidified. The directional solidification of γ/α2 lamellae was not affected by the precipitation of the β phase. Hot compression tests show that the deformation behavior of the β-containing lamellar microstructure also exhibits the anisotropic characteristic. The deformation resistance of the lamellae is lowest when the loading axis is aligned 45° to the lamellar interface. Microstructural observation shows that the decomposition of the lamellar microstructure tends to begin around the β phase, which benefits from the promotion of a soft β phase in the deformation. Moreover, the deformation mechanism of the lamellar microstructure was also studied. The bulging of the γ phase boundaries, the decomposition of α2 lamellae and the disappearance of γ/γ interfaces were considered as the main coarsening mechanisms of the lamellar microstructure.

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EFTENE, Alina, Alexandrina MANEA, Irina CALCIU, Anca Rovena LĂCĂTUȘU, Olga VIZITIU, Daniela RĂDUCU, and Sorina DUMITRU. "A SENSITIVE SANDY SOIL UNDER PASTURE AS MICROORGANISM HABITAT PROVIDER." "Annals of the University of Craiova - Agriculture Montanology Cadastre Series " 52, no. 1 (January 3, 2023): 390–93. http://dx.doi.org/10.52846/aamc.v52i1.1365.

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The sandy soils are sensitive ecosystems, being in a precarious equilibrium with the pedolandscape conditions, any changes could bring drastically modifications into the soil environment. The researches had been performed in Suceava Tableland, in Stephan the Great area, on a Luvosol albic-psamic, lamelar. The researches in the paper focused on the upper part of the argic horizon, on Bt1 sub-horizon characteristics at macro- and microscopic scale. In this respect, at the macro-morphological level, the Bt1 sub-horizon is composed of a sequence of thick lamellae (3–5 cm) separated by the inter-lamellar spaces. The granulometric analysis showed that the lamellae had a medium loamy texture, while the inter-lamellar spaces had coarse granulometric composition. At micromorphological level, the image emphasized, in the lamellae, the presence of the clayey±Fe±humiccoating the mineral grains and clogging part of the inter-granular spaces. The results of the microbiological investigation showed a concentration of the microorganisms into the lamellae, while in the inter-lamellar spaces, their development has been scarce. The total counts of bacteria and fungi registered low number (16.81 x 106 viable cells x g-1d.s. and 1.026 x 103cfus x g-1d.s., respectively). Despite of these results, the data of the global indicator of the soil microbiological activity, the soil respiration respectively, attend high level of activity (31.357 mg CO2 x g-1d.s.). The researches pointed out that the sandy soil is a very sensitive environment for the soil life, but the presence of the clayey±Fe lamellae proved to be a hospitable habitat.

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Egorov V. M., Borisov A. K., Marikhin V. A., Myasnikova L. P., Gurieva S. A., and Ivankova E. M. "Estimating the Dimensions of Nanocrystalline Elements of the Polyethylene Structure by Differential Scanning Calorimetry." Physics of the Solid State 64, no. 8 (2022): 1029. http://dx.doi.org/10.21883/pss.2022.08.54623.369.

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A method is proposed for calculating the dimension distribution of nanocrystalline elements of the lamellar and fibrillar morphologies of a polymer. Calorimetric data were used to calculate the distribution of the longitudinal size of these elements in lamellae and microfibrils of ultrahigh molecular weight polyethylene. The calculation results are consistent with the data obtained by the X-ray method.. Keywords: heat capacity, dimension effect, lamella, microfibril, polyethylene.

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8

Delivopoulos, S. G., and P. Kugrens. "Thylakoid formation from coiled lamellar bodies during carposporogenesis in Faucheocolax attenuata Setch. (Rhodophyta, Rhodymeniales)." Journal of Cell Science 75, no. 1 (April 1, 1985): 215–24. http://dx.doi.org/10.1242/jcs.75.1.215.

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Chloroplast development during carposporogenesis in the parasitic red alga Faucheocolax attenuata Setch. was studied by electron microscopy. Proplastids are usually found in the peripheral cytoplasm of young carpospores and are characterized by the presence of portions of a peripheral thylakoid and coiled lamellar bodies that range in size up to 0.5 micron. One type of coiled lamellar body occurs in the peripheral region of the proplastid and is continuous with the peripheral thylakoid, while the other type is found in the central portion of the stroma. These coiled lamellae separate and expand, adding membranes to both thylakoid systems, thereby functioning as thylakoid-forming bodies. As each coiled lamella unravels, it forms an undulated double-membraned structure having the same width as a thylakoid. After substantial expansion, the developing thylakoids begin to straighten and assume a parallel orientation to each other, thus becoming mature thylakoids. Small coiled lamellae often persist in mature carpospore chloroplasts, and are utilized in additional thylakoid formation during carpospore germination.

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9

Lidyana, Roslan, Tetsuya Ohashi, Yohei Yasuda, Kohsuke Takahashi, and Chikara Suruga. "Finite Element Analyses of Elasto-Plastic Deformation in Pearlite Lamellar and Colony Structures." Key Engineering Materials 626 (August 2014): 307–10. http://dx.doi.org/10.4028/www.scientific.net/kem.626.307.

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Elasto-plastic tensile deformations in pearlite lamellar and two-colony structures are studied by finite element analyses to investigate the effects of lamellar thickness ratio and difference of lamellae orientation of two colonies in pearlite microstructure. The results obtained from plastic strain distributions in lamellar and colony structures show that plastic deformation in cementite lamellar stabilized when ferrite lamellar is thicker than cementite lamellar thickness and plastic strain concentrates when the difference between cementite lamellar orientation in two colonies are larger than 45°.

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10

Malacarne, Bruno Dondoni, Rodrigo Ribeiro Martins, Cahuê Francisco Rosa Paz, João Victor Almeida Alves, Lucas Antunes Dias, Marina Alcantara Cavalcante, Alison Miranda Santos, et al. "Histological comparison of the lamellar tissue of Iberian origin breed horses created in semi-feral conditions or in an intensive system." PLOS ONE 18, no. 6 (June 1, 2023): e0286536. http://dx.doi.org/10.1371/journal.pone.0286536.

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Although the external conformation of wild horse hooves has been proposed as an ideal model for domesticated modern horses, histological signs of laminitis have been reported among them. With the hypothesis that the lamellar tissue of horses of Iberian origin raised in semi-feral is healthier than those raised in an intensive management system (stall confinement and high-calorie diet intake), the objective was to compare their lamellar tissues. Lamellar tissue samples were taken from the forelimb hoof of eight domesticated Mangalarga Marchador (MM) horses and from six semi-feral Marajoara (MJ) and Puruca (MP) horses. Primary epidermal lamella (PEL) and secondary epidermal lamella (SEL) were measured (length and width) in several regions, and their shapes were morphologically classified into different types. Breed groups were compared using analysis of variance, followed by Tukey or Dunn tests (P<0.05). Early signs of laminitis such as abnormal keratinization of the abaxial primary dermal lamella, tapered tips of the axial PELs, pointed tips of the SEL, nuclei condensation, and abnormal spatial orientation of the secondary epidermal basal cells (SELBC), were seen only in MM horses. MP horses had a greater interface of epidermis/dermis contact than MJ horses and more rounded nuclei in the round SELBC than MM horses. In agreement with the study hypothesis, semi-feral MJ and MP horses’ lamellae were classified as healthier than MM horses, which showed early signs of endocrinopathic laminitis.

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11

Kenedy, Gurumayum Robert, Korir Rosemary Chemeli, and Wei-Chun Cheng. "The Observation of Cellular Precipitation in an Ni36Co18Cr20Fe19Al7 High-Entropy Alloy after Quenching and Annealing." Materials 15, no. 19 (September 23, 2022): 6613. http://dx.doi.org/10.3390/ma15196613.

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High-entropy alloys (HEAs) comprise a minimum of five major elements. These alloys show some special characteristics, such as excellent mechanical and high temperature properties. The development of the HEAs requires a knowledge of phase transformations during alloy making procedures. The phase transformations of an Ni36Co18Cr20Fe19Al7 HEA were studied in this research. The alloy underwent hot forging, cold rolling, annealing at and quenching from 1323 K, and isothermal holding at 873 K. The alloy is a single face-centered cubic (FCC) phase in the as-quenched condition. After annealing at 873 K, not only fine coherent L12 particles precipitated homogeneously in the FCC matrix, but lamellae of FCC and L12 phases also developed from the grain boundaries. Both lamellar FCC and L12 grains have a cubic-on-cubic orientation relationship (OR). The composition of the lamellar L12 phase is Ni60Co8Cr6Fe6Al20, and that of the lamellar FCC phase is Ni31Co15Cr28Fe21Al4. Cellular precipitation occurs in the HEA, and the high-temperature FCC (γ) transforms to a lamella of low-temperature FCC (γ1), and an L12 phase, i.e., γ → γ1+L12.

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Li, G. L., M. Liu, and G. H. Wang. "Microstructure studies of potassium hexatitanate whiskers." Journal of Materials Research 16, no. 12 (December 2001): 3614–20. http://dx.doi.org/10.1557/jmr.2001.0495.

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Microstructures of potassium hexatitanate (K2Ti6O13) whiskers prepared by calcination of KF and TiO2 mixture were studied through high-resolution electron microscopy. The rod axis of a K2Ti6O13 whisker is along the [010] direction. These whiskers normally have a lamellar structure in their longitudinal direction, and adjacent lamellae usually have the same crystallographic orientation. Each lamella might be further divided into several fine layers with a width on the nanometer scale in the same crystallographic orientation. The whisker can be split in the longitudinal direction along either the boundary between two lamellae or the weak binding crystal plane, such as (100) and (201) planes. The mechanisms for the formation of lamella and layer structures and for the splitting of whiskers are discussed.

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13

Czarski, A., T. Skowronek, and P. Matusiewicz. "Stability of a Lamellar Structure – Effect of the True Interlamellar Spacing on the Durability of a Pearlite Colony / Stabilność Struktury Płytkowej – Wpływ Rzeczywistej Odległości Międzypłytkowej Na Trwałość Kolonii Perlitu." Archives of Metallurgy and Materials 60, no. 4 (December 1, 2015): 2499–504. http://dx.doi.org/10.1515/amm-2015-0405.

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A lamellar microstructure is, beside a granular and dispersive one, the most frequently observed microstructure in the case of metal alloys. The most well-known lamellar microstructure is pearlite, a product of a eutectoidal transformation in the Fe-Fe3C system. The lamellar morphology of pearlite - cementite and ferrite lamellae placed interchangeably within one structural unit described as a colony - is dominant. The durability of the lamellar morphology is much diversified: in the microstructure of spheroidizingly annealed samples, one can observe areas in which the cementite is thoroughly spheroidized, next to very well-preserved cementite lamellae or even whole colonies of lamellar pearlite. The mentioned situation is observed even after long annealing times. The causes of such behaviour can vary. The subject of the previous work of the authors was the effect of the orientation between the ferrite and the cementite on the stability of the lamellar morphology. This work constitutes a continuation of the mentioned paper and it concerns the effect of the true interlamellar spacing on the stability of the lamellar morphology of cementite.

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Lianxing, Gu, and Frank M. Vokes. "Intergrowths of hexagonal and monoclinic pyrrhotites in some sulphide ores from norway." Mineralogical Magazine 60, no. 399 (April 1996): 303–16. http://dx.doi.org/10.1180/minmag.1996.060.399.05.

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AbstractPyrrhotites in polished sections from more than twenty stratabound massive sulphide and magmatic nickel-copper deposits in Norway were studied under the microscope using the magnetic colloid method. In both types of deposits, two distinct styles of intergrowths between monoclinic and hexagonal pyrrhotites were found: crystallographically-controlled lamellar intergrowths and fissure-controlled irregular intergrowths.Lamellar intergrowths consist of crystallographically oriented monoclinic lamellae occurring in a hexagonal matrix and were produced originally by exsolution from hexagonal pyrrhotite on cooling. Irregular intergrowths comprise blades and patches of monoclinic pyrrhotite occurring along fissures and grain boundaries of hexagonal pyrrhotite, and were formed by interactions between hexagonal grains and sulphur-rich hydrothermal solutions.Increase in lamella thickness and spacing, development of lamella zonations, wedge-shaped composite ends, boxworks and composite lamellae were caused by progressive lamellae coarsening and maturation during natural annealing, which could have been promoted by anisotropic stress. Metamorphic recrystallization and annealing tend to homogenize pyrrhotite and erase preexisting exsolution lamellae.

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15

Li, Hui, Zhanglong Zhao, Yongquan Ning, Hongzhen Guo, and Zekun Yao. "Characterization of Microstructural Evolution for a Near-α Titanium Alloy with Different Initial Lamellar Microstructures." Metals 8, no. 12 (December 10, 2018): 1045. http://dx.doi.org/10.3390/met8121045.

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The effects of initial lamellar thickness on microstructural evolution and deformation behaviors of a near-α Ti-5.4Al-3.7Sn-3.3Zr-0.5Mo-0.4Si alloy were investigated during isothermal compression in α + β phase field. Special attention was paid to microstructural conversion mechanisms for α lamellae with different initial thicknesses. The deformation behaviors, including flow stress, temperature sensitivity, and strain rate sensitivity, and processing maps and their dependence on initial lamellar thickness were discussed. The detailed microstructural characterizations in different domains of the developed processing maps were analyzed. The results showed that the peak efficiency of power dissipation decreased with increasing initial lamellar thickness. The interaction effects with different extents of globularization, elongating, kinking, and phase transformation of lamellar α accounted for the variation in power dissipation. The flow instability region appeared to expand more widely for thicker initial lamellar microstructures during high strain rate deformation due to flow localization and local lamellae kinking. The electron backscatter diffraction (EBSD) analyses revealed that the collaborative mechanism of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) promoted the rapid globularization behavior for the thinnest acicular initial microstructure, whereas in case of the initial thick lamellar microstructure, CDRX leading to the fragmentation of lamellae was the dominant mechanism throughout the deformation process.

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Cheng, Xiang Jun, Guo Qing Wu, and Jia Qi Zhao. "Quantification and Statistical Analysis of Microstructural Features in As-Cast Ti-6Al-4V Titanium Alloy." Materials Science Forum 747-748 (February 2013): 828–32. http://dx.doi.org/10.4028/www.scientific.net/msf.747-748.828.

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Based on microstructure of as-cast Ti-6Al-4V titanium alloy, an image processing to simplify model of β grain size, α lamella space was developed and a quantitative statistical method of β grain size, α lamella space in two-phase titanium alloys was established, with which β grain size and α lamella space of as-cast Ti-6Al-4V titanium alloy with different plate thickness were analyzed. The relationship between β grain size, α lamellar space and cast plate thickness was discussed. The results show that β grain size and α lamellae thickness nearly linearly increase as plate thickness increasing. β grain size has normal distribution and with cast plate thickness increasing, the dispersion gets larger.

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Penfold, J., E. Staples, I. Tucker, G. J. T. Tiddy, and A. Khan Lodhi. "Shear-Induced Structures in Concentrated Surfactant Micellar Phases." Journal of Applied Crystallography 30, no. 5 (October 1, 1997): 744–49. http://dx.doi.org/10.1107/s0021889897001623.

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Constant and oscillatory Couette shear flow have been used in combination with small-angle neutron scattering to observe the shear-induced ordering in concentrated surfactant micellar phases. For the lamellar phase of hexaethylene glycol monohexadecyl ether, C16 E 6, two distinct lamellae orientations have been identified. At low shear gradients the lamellae are ordered parallel to the flow–vorticity plane, whereas at higher shear gradients the lamellae order parallel to the flow-shear gradient plane, corresponding to a rotation through 90° of the axis of orientation. At intermediate values of constant shear and for oscillatory shear, both lamellae orientations are simultaneously observed for the first time in a surfactant lamellar phase. For the lamellar phase, a dispersion of the binary surfactant mixtures of dioleyl cationic and 2-ethyl hexaglycerol monoether surfactants, a high degree of alignment, in the direction parallel to the flow–vorticity plane, is observed at zero and low shear. With time, during the application of a shear gradient of 25 s−1, the lamellar phase transforms to a highly ordered solution of monodisperse multilamellar vesicles.

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Shao, Fei Fei, Yu Feng Zhang, Jian Qiang Meng, and Zhen Liu. "Study on Lamellar Structures and Parameters of Polyethylene Hollow Fiber Membranes Made by Melt-Spinning and Stretching Method." Applied Mechanics and Materials 178-181 (May 2012): 491–94. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.491.

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Lamellas important for micropores were well formed during extrusion and annealing process in melt-spinning and stretching method. This unusual crystalline structure and its changing during annealing and stretching process were well studied in term of lamellar size, lamellar crystallite orientation, degree of lamellar and observation of morphology. Lamellar and microfibril model was accepted as mechanism of making micropore for this process. Gas permeability and porosity testing experimental were used to characterize membrane properties.

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Journal, Baghdad Science. "Effect of vydate gill histology in female mosquito fish Gambusia affinis (Baird and Girard)." Baghdad Science Journal 14, no. 1 (March 5, 2017): 1–10. http://dx.doi.org/10.21123/bsj.14.1.1-10.

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This study aimed to identify the histological changes of mosquito fish (Gambusia affinis) exposed to vydate pesticide. (48) female fishes were collected from local markets and also from the stream that surround Baghdad university campus at Al-jadyria, fishes divided into (4) groups and each group consist of 12 fish: T1(exposed to 0.0000001 mg/L),T2 (exposed to 0.0000002 mg/L ) and T3 (exposed to 0.000001 mg /L) of vydate pesticide for (8) weeks. As well as a control group. Fishes were dissected for histological preparations after each (2,4,6,8) weeks of exposure time. Gills were fixed by Bouin’s fluid and stained with Hematoxylin and eosin. Histological study showed that the structure of gill in a control group consists of primary and secondary gill lamellae appeared parallel and oblique. The secondary gill lamellae lined with squamous epithelial and pillar cells, and each secondary lamellae have capillary derived from blood vessel in primary lamellae, chlorid cells and few mucous cells found between secondary lamellae. The histological alterations in gills included hyperplasia of chloride cells, congestion of blood vessels, lamellar disarray, lifting of epithelial cells, Oedema, fusion of adjacent secondary lamella and Aneurysm. Results concluded that vydate had a vicious effect on gills and caused severe histological alterations such as hyperplasia of chloride cells and simple alterations such as lamellar disarray, and also these histological changes commensurate direct proportion with concentrations were used in this study.

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Gupta, H. S., U. Stachewicz, W. Wagermaier, P. Roschger, H. D. Wagner, and P. Fratzl. "Mechanical modulation at the lamellar level in osteonal bone." Journal of Materials Research 21, no. 8 (August 1, 2006): 1913–21. http://dx.doi.org/10.1557/jmr.2006.0234.

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The secondary osteon is the fundamental building block of compact cortical bone at the tissue level. Light and scanning electron microscopy have shown that the osteon consists of a laminated cylindrical composite of mineralized collagen fibril lamellae ∼5–7 μm thick. Using scanning nanoindentation and quantitative backscattered electron imaging on secondary osteons from the human femoral midshaft, we found that the indentation modulus shows a periodic variation between ∼24 GPa and ∼27 GPa within a single lamella. The average lamellar value remains nearly constant across the osteon and increases abruptly to more than 30 GPa at the interstitial bone interface. The local mineral content, determined from quantitative backscattered electron imaging at the indented locations, shows also a lamellar level modulation and is positively correlated with the indentation modulus at the same tissue position. We propose that such a mechanically and compositionally modulated structure may be an effective crack-stopping mechanism in bone.

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Cho, Ken, Hirotaka Odo, Keisuke Okamoto, Hiroyuki Y. Yasuda, Hirotoyo Nakashima, Masao Takeyama, and Takayoshi Nakano. "Improving the Tensile Properties of Additively Manufactured β-Containing TiAl Alloys via Microstructure Control Focusing on Cellular Precipitation Reaction." Crystals 11, no. 7 (July 12, 2021): 809. http://dx.doi.org/10.3390/cryst11070809.

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The effect of a two-step heat treatment on the microstructure and high-temperature tensile properties of β-containing Ti-44Al-4Cr (at%) alloys fabricated by electron beam powder bed fusion were examined by focusing on the morphology of α2/γ lamellar grains and β/γ cells precipitated at the lamellar grain boundaries by a cellular precipitation reaction. The alloys subjected to the first heat treatment step at 1573 K in the α + β two-phase region exhibit a non-equilibrium microstructure consisting of the α2/γ lamellar grains with a fine lamellar spacing and a β/γ duplex structure located at the grain boundaries. In the second step of heat treatment, i.e., aging at 1273 K in the β + γ two-phase region, the β/γ cells are discontinuously precipitated from the lamellar grain boundaries due to excess Cr supersaturation in the lamellae. The volume fraction of the cells and lamellar spacing increase with increasing aging time and affect the tensile properties of the alloys. The aged alloys exhibit higher strength and comparable elongation at 1023 K when compared to the as-built alloys. The strength of these alloys is strongly dependent on the volume fraction and lamellar spacing of the α2/γ lamellae. In addition, the morphology of the β/γ cells is also an important factor controlling the fracture mode and ductility of these alloys.

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Seiler, Wilfrid, G. Hoël, Marc Thomas, and Vincent Ji. "XRD Stress Analysis in a TiAl Based Intermetallic Multicrystal." Materials Science Forum 490-491 (July 2005): 684–89. http://dx.doi.org/10.4028/www.scientific.net/msf.490-491.684.

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Under specific manufacturing processes and heat treatments, the gamma titanium Aluminide Ti- 47Al-2Cr-2Nb presents a nearly lamellar microstructure with coarse lamellar grains (with alternating g and a2 lamellae) and dispersed small g grains. The obtained microstructure gives a relatively coarse grain size (approximately 0.4 mm x 3 mm). Residual stresses can then be generated between g and a2 lamellae inside the lamellar grain and also between different grains because of the lattice mismatch between tetragonal structure of g phase and hexagonal structure of a2 phase. A specific single crystalline XRD method is applied on these two non-cubic phases to determine the local residual stresses in two grains on each side of a grain boundary.

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Westfahl Jr, Harry, and Mateus Borba Cardoso. "Accessing the hidden lamellar nanostructure of semi-crystalline nascent polymers by small-angle X-ray scattering contrast variation." Journal of Applied Crystallography 44, no. 5 (September 8, 2011): 1123–26. http://dx.doi.org/10.1107/s0021889811033255.

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Most melt-crystallized polymers present a lamellar nanostructure of alternating crystalline and amorphous lamellae which is coherent enough to display a broad interference peak in small-angle X-ray scattering experiments (SAXS). Nascent semi-crystalline polymers, on the other hand, though highly crystalline, hardly show an interference peak. This has long been attributed either to the formation of extended chain crystals or to a highly incoherent lamellar stacking. Here it is shown that a coherent lamellar order is shaded by a large scattering contribution from the air/grain interface. This is revealed by a SAXS contrast variation technique that suppresses the air/grain interface scattering and leaves only the scattering contribution from the internal lamellae.

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Ciccariello, Salvino, and Roger Sobry. "Small-angle scattering intensity behaviours of cylindrical, spherical and planar lamellae." Journal of Applied Crystallography 32, no. 5 (October 1, 1999): 892–901. http://dx.doi.org/10.1107/s0021889899005610.

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Analytical asymptotic expressions for the small-angle scattering intensities of cylindrical, spherical and planar lamellar grains are determined. Denoting the lamellar spacing byDand the number of lamellae byN, it is found that in the corresponding Porod plots, the positions of the main peaks, whatever the shape, are nearly given by 2k\pi/D, wherekis a positive integer. At a fixed number of lamellar grains, the heights of the main peaks in the three cases increase withNasN3,N4andN2, respectively. The satellite peaks are much more structured for cylindrical and spherical lamellae than for planar ones. The momentum-transfer (h) range in which the asymptotic expressions turn out to be accurate is h\ge 2\pi/ND.

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25

Yu, Tian Bo, Niels Hansen, and Xiao Xu Huang. "Triple Junction Motion – A New Recovery Mechanism in Metals Deformed to Large Strains." Materials Science Forum 753 (March 2013): 485–88. http://dx.doi.org/10.4028/www.scientific.net/msf.753.485.

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A phenomenologically new recovery mechanism – triple junction motion is presented. This recovery mechanism is found to be the dominant one at low and medium temperatures in highly strained aluminum, which has a very fine microstructure, composed of lamellae with the thickness of a few hundred nanometers. Triple junction motion leads to removal of thin lamellae and to a consequent increase of the thickness of neighboring lamellae. This recovery mechanism therefore increases the average lamellar boundary spacing and causes a gradual transition from a lamellar structure to a more equiaxed structure preceding recrystallization.

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26

Kong, Fan Tao, and Yu Yong Chen. "The Effect of Heat Treatment on the Microstructure of Ti-45Al-5Nb-0.3Y Alloy." Materials Science Forum 614 (March 2009): 55–59. http://dx.doi.org/10.4028/www.scientific.net/msf.614.55.

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Effects of heat treatment on the microstructure of as-cast and as-forged Ti-45Al-5Nb-0.3Y alloy are discussed. The as-cast Ti-45Al-5Nb-0.3Y alloy exhibits a microstructure consisting of fine equiaxed grains which average size is almost 100μm. Phase transformation of as-cast Ti-45Al-5Nb-0.3Y alloy greatly depends upon cooling rate. During furnace cooling, the alloy transform to fully lamellar microstructure. During air cooling, massive transformation predominates. During oil cooling, extremely fine fully lamellar microstructure is formed. During water cooling, ordering α2 phases are primary. Thermo-mechanical treatments, through combined action of hot canned forging and heat treatment, were performed on a Ti-45Al-5Nb-0.3Y alloy to investigate their effect on the microstructure of the alloy. The as-forged Ti-45Al-5Nb-0.3Y alloy is comprised of a large number of dynamic recrystallization (DRX) γ grains, curved and broken lamellae, and a small amount of remnant lamellae. And three different microstructures, duplex (DP), nearly lamellar (NL) and fine fully lamellar (FFL), have been obtained through heat treatment at different temperatures (1320-1370°C), respectively.

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27

Robinson, Peter, S. A. McEnroe, R. J. Harrison, K. Fabian, F. Heidelbach, and M. Jackson. "Lamellar magnetism and exchange bias in billion-year-old metamorphic titanohematite with nanoscale ilmenite exsolution lamellae – III. Atomic-magnetic basis for experimental results." Geophysical Journal International 226, no. 2 (April 29, 2021): 1348–67. http://dx.doi.org/10.1093/gji/ggab176.

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SUMMARY Lamellar magnetism is a source of remanent magnetization in natural rocks different from common bulk magnetic moments in ferrimagnetic minerals. It has been found to be a source for a wide class of magnetic anomalies with extremely high Koenigsberger ratio. Its physical origin are uncompensated interface moments in contact layers of nanoscale ilmenite lamellae inside an hematite host, which also generate unusual low-temperature (low-T) magnetic properties, such as shifted low-T hysteresis loops due to exchange bias. The atomic-magnetic basis for the exchange bias discovered in the hematite-ilmenite system is explored in a series of papers. In this third article of the series, simple models are developed for lamellae interactions of different structures when samples are either cooled in zero-field, or field-cooled in 5 T to temperatures below the ordering temperature of ilmenite. These models are built on the low-temperature measurements described earlier in Paper II. The important observations include: (i) the effects of lamellar shapes on magnetic coupling, (ii) the high-T acquisition of lamellar magnetism and low-T acquisition of magnetization of ilmenite lamellae, (iii) the intensity of lamellar magnetism and the consequent ilmenite magnetism in populations of randomly oriented crystals, (iv) lattice-preferred orientation of the titanohematite host crystal populations and (v) the effects of magnetic domain walls in the host on hysteresis properties. Based on exemplary growth models of lamellae with different geometries and surface couplings we here provide simple models to assess and explain the different observations listed above. Already the simplified models show that the shapes of the edges of ilmenite lamellae against their hematite hosts can control the degree of low-T coupling between ilmenite, and the lamellar magnetic moments. The models also explain certain features of the low-T exchange bias in the natural samples and emphasize the role of lattice-preferred orientation upon the intensity of remanent magnetization. The inverse link between ilmenite remanence and exchange-bias shift in bimodal low-T ilmenite lamellae is related to different densities of hematite domain walls induced by the clusters of ilmenite lamellae.

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28

Luchnikov, Valeriy A., and Dimitri A. Ivanov. "Theory of geometrical broadening of diffraction peaks from twisted lamellar crystals for interpretation of X-ray microbeam and selected-area electron diffraction experiments." Journal of Applied Crystallography 43, no. 3 (April 15, 2010): 578–86. http://dx.doi.org/10.1107/s0021889810008873.

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A simple theory of angular broadening of diffraction peaks is presented for the X-ray and electron diffraction from twisted crystalline lamellae. The diffraction peak position, width and asymmetry are computed in the limit of a small natural reflection width. The peak broadening depends on the orientation of the corresponding reciprocal-space vector with respect to the helicoid axis and the normal to the lamellar basal plane. It is found that the equatorial peaks, which are close to the normal direction to the lamellar basal plane, are characterized by the highest azimuthal width. The theory also describes the azimuthal drift of the non-equatorial reflections on a flat two-dimensional detector as the incident beam scans along the main helicoid axis. The proposed approach can be useful for interpretation of microbeam diffractograms measured on banded polymer spherulites. It can be easily generalized to describe diffraction from crystals of any arbitrary shape obtained by deformation of a flat lamella, under the condition that upon the deformation all the in-plane angles and distances are preserved in the linear approximation.

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29

Hu, J. F., P. Qi, J. M. Yin, X. K. Hou, B. L. Li, S. P. Wen, W. Wei, and Z. R. Nie. "Effect of α+β phase rolling and aging treatment on laminated bimodal structure in high temperature titanium alloy." Journal of Physics: Conference Series 2635, no. 1 (November 1, 2023): 012005. http://dx.doi.org/10.1088/1742-6596/2635/1/012005.

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Abstract In this work, we have prepared a novel laminated bimodal structure with layer-by-layer distribution of αp and αs phase in high temperature titanium alloy by α+β phase rolling and aging treatment. The lamellar bimodal microstructure is comprised of long-primary αp and secondary αs phase in the Ti-6.0Al-3Sn-5Zr-0.5Mo-1.0Nb-1.0Ta-0.4Si-0.2Er alloy. During α+β phase rolling at 990 °C, the primary αp grain deformed to elongated layer structure, while the lamella secondary αs deformed to kinked and broken chaos morphology. After 800 °C for 1h stabilization and 700 °C for 5h aging treatment, the thickness of the elongated αp layer slightly grew, while the kinked and broken αs were recovered and partially recrystallized to form a layered fine grain structure. The lamellar bimodal microstructure, i.e., elongated primary αp with layered bimodal αs phase has enhanced strength and ductility of the high temperature titanium alloy. This enhanced strength and toughness is mainly attributed to the lamellae αp structure and layered fine αs grain formed by hot rolling and aging treatment.

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30

Beck, Ulrich, Patrick Elter, Regina Lange, and Andrea Ewald. "Lamellar Surface Structures on Stainless Steel 316 LVM and their Influence on Osteoblastic Cells." Materials Science Forum 638-642 (January 2010): 501–5. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.501.

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In this study, nanoscaled lamellar surface structures were prepared on medical stainless steel by chemical etching of the decomposed phases and their effect on the morphology of osteoblastic cells was investigated using Field Emission Scanning Electron Microscopy. Long filopodia were grown from the cells perpendicular to the lamellar structure while almost no or only short filopodia are formed parallel to the lamellae. The results are explained by a different surface roughness parallel and perpendicular to the lamellae: During the growth process of the filopodia a nearly flat surface is recognized parallel to the lamellae while a topographical change is sensed perpendicular to the structure, which is preferred by the cells.

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31

Babout, L., J. Quinta Da Fonseca, and Michael Preuss. "Local Strain Imaging during Mechanical Loading of Lamellar Microstructures in Titanium Based Alloys." Applied Mechanics and Materials 1-2 (September 2004): 159–64. http://dx.doi.org/10.4028/www.scientific.net/amm.1-2.159.

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In this work optical microscopy in situ tensile testing has been carried out to study the localisation of surface strain in fully lamellar titanium alloys. The localised strain was measured by analysing the recorded optical micrographs using image correlation, and the orientation of the a lamellae colony was determined by using Electron Back Scatter Diffraction (EBSD). The results show a localisation of strain, which seems to depend on the crystallographic orientation of the a lamellae colony in the lamellar microstructure. No significant strain was observed in the former b grain boundary region.

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32

Gupta, Shant P., Satish K. Goutam, and P. Suresh Babu. "Discontinuous precipitation of a liquid in Cu-base alloys – nucleation and growth mechanisms." International Journal of Materials Research 94, no. 4 (April 1, 2003): 442–48. http://dx.doi.org/10.1515/ijmr-2003-0076.

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Abstract The morphology of discontinuous precipitation of a liquid has been studied in Cu-9.5 at.% In and Cu-7.5 at.% Sn alloys. The transformation of a supersaturated solid solution (αo) was carried out in the two-phase (α + liquid) field. A lamellar structure, consisting of alternate solute-depleted (α) and liquid phases, has been observed to grow from grain boundaries of the supersaturated αo. The nucleation of the liquid droplets occurred at grain boundaries as two hemispherical caps abutted at the original grain boundary positions. A thin liquid film replaced the grain boundary and started migrating as the transformation progressed. The lamellae multiplication occurred by nucleation of new lamellae at the migrating front. The lamellae multiplication also occurred by nucleation of new lamellae at mid-lines between the liquid lamellae where the interlamellar spacing was large. A cylindrical loop of liquid formed behind a migrating liquid film, resulting into double-seam morphology and an irregular lamellar structure on one side of the original grain boundary. The liquid film also migrated in the shape of sine wave when the liquid film between neighbouring droplets migrated in opposite directions near the original grain boundary. This has resulted in double-seam morphology with a regular lamellar structure.

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33

Di Girolamo, Rocco, Alessandra Cicolella, Giovanni Talarico, Miriam Scoti, Fabio De Stefano, Angelo Giordano, Anna Malafronte, and Claudio De Rosa. "Structure and Morphology of Crystalline Syndiotactic Polypropylene-Polyethylene Block Copolymers." Polymers 14, no. 8 (April 10, 2022): 1534. http://dx.doi.org/10.3390/polym14081534.

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A study of the structure and morphology of diblock copolymers composed of crystallizable blocks of polyethylene (PE) and syndiotactic polypropylene (sPP) having different lengths is reported. In both analyzed samples, the PE block crystallizes first by cooling from the melt (at 130 °C) and the sPP block crystallizes after at a lower temperature. Small angle X-ray scattering (SAXS) recorded during cooling showed three correlation peaks at values of the scattering vector, q1 = 0.12 nm−1, q2 = 0.24 nm−1 and q3 = 0.4 nm−1, indicating development of a lamellar morphology, where lamellar domains of PE and sPP alternate, each domain containing stacks of crystalline lamellae of PE or sPP sandwiched by their own amorphous phase of PE or sPP. At temperatures higher than 120 °C, when only PE crystals are formed, the morphology is defined by the formation of stacks of PE lamellae (17 nm thick) alternating with amorphous layers and with a long period of nearly 52 nm. At lower temperatures, when crystals of sPP are also well-formed, the morphology is more complex. A model of the morphology at room temperature is proposed based on the correlation distances determined from the self-correlation functions extracted from the SAXS data. Lamellar domains of PE (41.5 nm thick) and sPP (8.2 nm thick) alternate, each domain containing stacks of crystalline lamellae sandwiched by their own amorphous phase, forming a global morphology having a total lamellar periodicity of 49.7 nm, characterized by alternating amorphous and crystalline layers, where the crystalline layers are alternatively made of stacks of PE lamellae (22 nm thick) and thinner sPP lamellae (only 3.5 nm thick).

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34

Zhu, Li Wei, Zhi Shou Zhu, Xin Nan Wang, and Chun Xiao Cao. "The Effect of Microstructure on Mechanical Properties and Fatigue Crack Growth Behavior of TC4-DT Alloy." Advanced Materials Research 490-495 (March 2012): 3767–72. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.3767.

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This paper examines the influence of different microstructure on the mechanical properties and fatigue crack growth behavior of TC4-DT alloy at room temperature. Different heat treatments were carried out in order to produce the microstructure of bimodal and lamellar conditions. Results show that, the tensile properties and fracture toughness of bimodal and lamellar microstructure was varied by different heat-treatment. In contrast on bimodal microstructure, the lamellar microstructure presents high fracture toughness and low fatigue crack growth rate, but the yield stress and ductility declines. The analysis results indicted that the lamellar microstructure obtained by air cooling from the  phase field showed the integrated condition of tensile properties and fracture toughness duo to the fine secondary  lamella, and the better fatigue crack growth behavior.

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35

Watanabe, II-Sei, and Chizuka Ide. "Cholinesterase activity of lamellated sensory corpuscles in the rat lip." Arquivos de Neuro-Psiquiatria 44, no. 4 (December 1986): 325–33. http://dx.doi.org/10.1590/s0004-282x1986000400002.

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Non-specific cholinesterase (ChE) activity was demonstrated in lamellated sensory corpuscles of the rat lip by light and electron microscopy using Karnovsky and Root's method. ChE activity was present in the interlamellar spaces between neighbouring lamellae as well as in the periaxonal space between axon terminals and their adjacent lamellae. Reaction products of ChE activity were also deposited in some caveolae of the lamellar cell plasma membrane, and in the cisternae of the rough endoplasmic reticulum as well as in the nuclear envelope of lamellar cell bodies. No definite reaction products were detected within the axon terminals. These findings show that the lamellated corpuscles in the rat lip, like other mechanoreceptors, have an intense ChE activity which is mainly associated with lamellar cells. It can be said that ChE histochemistry is useful to detect mechanoreceptors. The functional significance of ChE in mechanoreceptors is discussed.

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36

Larson, D. J., M. K. Miller, H. Inui, and M. Yamaguchi. "Atom Probe Field Ion Microscopy of Poly Synthetically Twinned Titanium Aluminide." Microscopy and Microanalysis 4, S2 (July 1998): 102–3. http://dx.doi.org/10.1017/s1431927600020638.

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Two phase γ-based TiAl alloys are attractive for structural applications at high temperatures because they possess good elevated-temperature mechanical properties, low density, and good creep and oxidation resistance. The microstructures of these alloys consist of plates of the near equiatomic γ phase (L10-ordered structure) and the Ti3Al α2 phase (D019-ordered structure). It is of great interest to study the details of the lamellar α2+γ microstructure because the interface stability is the key to providing a usable high temperature material.Polysynthetically twinned (PST) TiAl crystals have been developed in order to systematically study the lamellar microstructure. These PST materials contain no high angle grain boundaries and have an single set of aligned lamellae of a α2 and γ phases, as shown in Fig. 1. Therefore, PST samples facilitate the study of the dependence of mechanical properties on lamellar structure by providing a known, consistent set of aligned lamellae.

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37

Le Borgne, T., P. D. Huck, M. Dentz, and E. Villermaux. "Scalar gradients in stirred mixtures and the deconstruction of random fields." Journal of Fluid Mechanics 812 (January 5, 2017): 578–610. http://dx.doi.org/10.1017/jfm.2016.799.

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A general theory for predicting the distribution of scalar gradients (or concentration differences) in heterogeneous flows is proposed. The evolution of scalar fields is quantified from the analysis of the evolution of elementary lamellar structures, which naturally form under the stretching action of the flows. Spatial correlations in scalar fields, and concentration gradients, hence develop through diffusive aggregation of stretched lamellae. Concentration levels at neighbouring spatial locations result from a history of lamella aggregation, which is partly common to the two locations. Concentration differences eliminate this common part, and thus depend only on lamellae that have aggregated independently. Using this principle, we propose a theory which envisions concentration increments as the result of a deconstruction of the basic lamella assemblage. This framework provides analytical expressions for concentration increment probability density functions (PDFs) over any spatial increments for a range of flow systems, including turbulent flows and low-Reynolds-number porous media flows, for confined and dispersing mixtures. Through this deconstruction principle, scalar increment distributions reveal the elementary stretching and aggregation mechanisms building scalar fields.

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38

Albano, Juan, Damian Grillo, Julio Facelli, Marta Ferraro, and Mónica Pickholz. "Study of the Lamellar and Micellar Phases of Pluronic F127: A Molecular Dynamics Approach." Processes 7, no. 9 (September 7, 2019): 606. http://dx.doi.org/10.3390/pr7090606.

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In this work, we analyzed the behavior of Pluronic F127 through molecular dynamics simulations at the coarse-grain level, focusing on the micellar and lamellar phases. To this aim, two initial polymer conformations were considered, S-shape and U-shape, for both simulated phases. Through the simulations, we were able to examine the structural and mechanical properties that are difficult to access through experiments. Since no transition between S and U shapes was observed in our simulations, we inferred that all single co-polymers had memory of their initial configuration. Nevertheless, most copolymers had a more complex amorphous structure, where hydrophilic beads were part of the lamellar-like core. Finally, an overall comparison of the micellar a lamellar phases showed that the lamellar thickness was in the same order of magnitude as the micelle diameter (approx. 30 nm). Therefore, high micelle concentration could lead to lamellar formation. With this new information, we could understand lamellae as orderly packed micelles.

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39

Stagni, L., and R. Lizzio. "Interaction Between an Edge Dislocation and a Lamellar Inhomogeneity With a Slipping Interface." Journal of Applied Mechanics 59, no. 1 (March 1, 1992): 215–17. http://dx.doi.org/10.1115/1.2899434.

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The plane elasticity problem of an internal stress source located near a lamellar inhomogeneity is considered. It is assumed that the lamella-matrix interface does not transmit tangential displacements or shear tractions (slipping interface). The elastic field is given in terms of the source bulk field and one parameter formed from the elastic constants. The image force on an edge dislocation near the lamella is calculated and discussed. A dislocation stable-equilibrium position exists in a domain of elastic constants and Burgers vector directions. This result is characteristic of the interaction with a slipping lamellar inhomogeneity having finite thickness.

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40

Zhang, Shuling, Ning Cui, Wei Sun, and Qiucheng Li. "Microstructural Characterization and Crack Propagation Behavior of a Novel β-Solidifying TiAl Alloy." Metals 11, no. 8 (August 2, 2021): 1231. http://dx.doi.org/10.3390/met11081231.

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Novel β-solidifying TiAl alloys have great potential for engineering applications in the aerospace and automotive industries. The introduction of the β0 phase will inevitably affect crack propagation. However, the related mechanism is unclear. In this study, the crack propagation behavior of different β0-containing microstructures was systematically investigated by three-point bending tests. The results show that the coarse γ/α2 lamellar microstructure exhibits better fracture toughness than the fine-grain microstructure because large numbers of γ/α2 lamellar boundaries can effectively hinder crack propagation. The propagation direction depends largely on the orientation of the γ/α2 lamellae. When the angle between the crack propagation direction and the γ/α2 lamellar boundary is small, the crack tends to propagate along γ/α2 lamellae. When the angle is close to 90°, the crack generally propagates by the trans-lamellar mode. Moreover, the crack tends to traverse across the fine β0/γ duplex region due to the low resistance of fine grains in the crack propagation. The transgranular and intergranular modes are the main fracture mechanisms in the microstructure of the fine β0/γ grains. Some shear ligaments can also be identified in the lamellar microstructure and these can consume propagation energy. The enlarged image shows that the crack propagation direction can be changed by the β0 phase, owing to its high hardness. The crack tends to stop at the β0 phase region.

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41

ZHANG, Zhixiong, Ruirui WU, Jie HOU, and Tao WANG. "Characterization of Microstructure and Mechanical Properties of Ti-6Al-4V Alloy after Cyclic Heat Treatment." Materials Science 27, no. 1 (January 15, 2021): 27–31. http://dx.doi.org/10.5755/j02.ms.23023.

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A cost-effective approach which consists of cyclic heat treatment (CHT) and annealing is used to refine the coarse lamellar structure of as-cast Ti-6Al-4V alloy. The coarse lamellar microstructure was significantly refined after the CHT process, α lamellae were broken up while the original orientations of α lamellae were maintained. After annealing treatment, a basketweave microstructure was achieved in Ti-6Al-4V alloy, and the formation of globular α grains was observed. The microstructure refinement mechanisms during CHT and annealing are mainly considered to be break-up of lamellar structure and static recrystallization. The room temperature mechanical properties of Ti-6Al-4V alloy were significantly improved. The microhardness of Ti-6Al-4V alloy increased from 306 HV to 402 HV. The values of yield strength (YS) and ultimate tensile strength (UTS) increased from 734 MPa and 740 MPa to 911 MPa and 1010 MPa, respectively. The value of ductility increased from 1.1 % to 3.3 %.

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42

Zhang, Wei, Yong Mao, Jia Jia Song, Jin Xin Guo, and Si Yong Xu. "Hot Compression Deformation Behaviors and Microstructure Evolution for Brittle Au-20Sn Eutectic Alloy." Materials Science Forum 789 (April 2014): 409–14. http://dx.doi.org/10.4028/www.scientific.net/msf.789.409.

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The hot compression test of Au-20Sn alloys with different solidification structures was carried out. The deformation behaviors and microstructure evolutions during hot compression were investigated. The results indicate that the fine fully lamellar eutectic structure without primary phase exhibited a very low yielding stress and a low stress platform, while the coarse lamellar with large primary Au5Sn phase showed rather high in that value. After compression, the lamellar eutectic tended to be equiaxed due to dynamic recrystallization, the large primary phase became separate dendrites or split into small dendrites, and the small roselike primary phase partly dissolved in the eutectic matrix. The rate of recrystallization also increased as the primary phase eliminated and lamellae was refined. It is suggested that refining eutectic lamellae and eliminating the primary Au5Sn phase in the as-cast microstructure by solidification optimization are an effective way to improve the workability greatly for brittle Au-20Sn eutectic alloy.

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43

Zheng, Gong, Yang Chen, Henggao Xiang, Jinpeng Zhang, K. N. Tu, Chenming Feng, Pei Li, et al. "Coupled nucleation of dual-phase lamellar structure." Innovation Materials 1, no. 3 (2023): 100043. http://dx.doi.org/10.59717/j.xinn-mater.2023.100043.

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<p>Although lamellar structures widely exist in materials, the existing nucleation knowledge has failed to describe the nucleation process of lamellae. This is because it involves the simultaneous formation of two different phases whose early-stage nuclei are always anisotropic and ordered. We report here a coupled nucleation of lamellae in a eutectoid TiAl system, demonstrating the coupled formation of a pair of anisotropic and ordered ��<sub>2</sub> + �� lamellae from the matrix, and each pair nucleates independently and heterogeneously. The coupled pair has been identified by alternative segregation of Nb in the interface using atom probe tomography. The nucleation kinetics have been confirmed by atomistic simulations and in situ high-energy synchrotron X-ray diffraction. A theoretical model has been proposed for this heterogeneously coupled nucleation, offering potential applications in various systems or phase transitions involving anisotropic, ordered, or lamellar structures. This coupled nucleation model represents a significant enhancement to the existing nucleation theory.</p>

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44

Wolfgang, W. J., D. Fristrom, and J. W. Fristrom. "The pupal cuticle of Drosophila: differential ultrastructural immunolocalization of cuticle proteins." Journal of Cell Biology 102, no. 1 (January 1, 1986): 306–11. http://dx.doi.org/10.1083/jcb.102.1.306.

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Precise ultrastructural localization of Drosophila melanogaster pupal cuticle proteins (PCPs) was achieved by the immunogold labeling of frozen thin sections. PCPs were found in lamellate cuticle and intracellular vesicles but, curiously, were absent from the assembly zone of the cuticle. Antibodies that distinguish between the two classes of PCPs--low molecular weight (L-PCPs) and high molecular weight (H-PCPs)--revealed that the morphologically distinct outer lamellae contained L-PCPs and the inner lamellae contained H-PCPs. The sharp boundary between these two antigenic domains coincides with the transition from the outer to the inner lamellae, which in turn is correlated with the cessation of L-PCP synthesis and the initiation of H-PCP synthesis in response to 20-hydroxyecdysone (Doctor, J., D. Fristrom, and J.W. Fristrom, 1985, J. Cell Biol. 101:189-200). Hence, differences in protein composition are associated with differences in lamellar morphology.

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45

Luchnikov, Valeriy A., and Dimitri A. Ivanov. "Microbeam X-ray diffraction from twisted lamellar crystals: theory and computer simulation." Journal of Applied Crystallography 42, no. 4 (June 13, 2009): 673–80. http://dx.doi.org/10.1107/s0021889809017877.

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The diffraction peak position, width and intensity distribution are calculated for the case of a helicoidally twisted crystalline lamella, both analytically and numerically. It is shown that the diffraction peak broadening depends on the orientation of the corresponding reciprocal-space vector with respect to the helicoid axis and the normal to the lamellar basal plane. The equatorial peaks, which are close to the normal direction to the lamellar basal plane, are characterized by the highest azimuthal width. By contrast, the reflections positioned close to the lamellar surface have the smallest azimuthal width. For non-equatorial peaks in the proximity of the twisting axis the intensity has an unusual asymmetric shape. The shape of the microbeam, as well as its position and direction with respect to the lamella, influences the shape of the diffraction peaks in reciprocal space and their appearance in two-dimensional diffractograms. The proposed approach can be useful, for example, for the interpretation of microbeam diffractograms of banded polymer spherulites.

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46

Hamley, Ian W. "Diffuse scattering from lamellar structures." Soft Matter 18, no. 4 (2022): 711–21. http://dx.doi.org/10.1039/d1sm01758f.

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Fluctuations in lamellar phases give rise to diffuse scattering, which can provide valuable information on the elastic properties of lamellae. Models to account for this are described, and diffuse scattering from in-plane fluctuations or structures such as perforations or patterned nanoparticles is considered.

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47

Zhang, Lan Ting, Ou Zhu, Yan Jiang, Ai Dang Shan, and Jian Sheng Wu. "Growth of Crystals and Formation of C40/C11_b Lamellar Structure in (Mo_0.85Nb_0.15)Si₂." Materials Science Forum 638-642 (January 2010): 1434–38. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1434.

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In this paper, high-quality single crystals of (Mo0.85Nb0.15)Si2, around 8 mm in diameter and 90 mm in length, have been grown by optical heating floating zone method. Effects of chemical composition and growth rate on forming C40 structured single crystal were studied. Aligned C40/C11b lamellar structured can be formed in the as-grown crystals after post annealing at temperatures between 1473 and 1873 K. Chemical composition as well as annealing temperature are found to be two important factors to form C11b lamellae in the C40 matrix. Fully C40/C11b lamellar structure was formed after annealing at 1873 K in the present work. The aligned C40 and C11b lamellae follow a crystallographic orientation relationship of (0001)C40//(110)C11b. Dislocations were observed in some coarse C11b lamellae but never in C40 lamellae of the duplex structure. This is probably due to accumulation of misfit strain during formation of C40/C11b lamellae.

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48

Chen, R. T., M. G. Jamieson, and R. Callahan. "SEM/FESEM imaging of lamellar structures in melt extruded polyethylene films." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (August 1992): 1142–43. http://dx.doi.org/10.1017/s0424820100130341.

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“Row lamellar” structures have previously been observed when highly crystalline polymers are melt-extruded and recrystallized under high stress. With annealing to perfect the stacked lamellar superstructure and subsequent stretching in the machine (extrusion) direction, slit-like micropores form between the stacked lamellae. This process has been adopted to produce polymeric membranes on a commercial scale with controlled microporous structures. In order to produce the desired pore morphology, row lamellar structures must be established in the membrane precursors, i.e., as-extruded and annealed polymer films or hollow fibers. Due to the lack of pronounced surface topography, the lamellar structures have typically been investigated by replica-TEM, an indirect and time consuming procedure. Recently, with the availability of high resolution imaging techniques such as scanning tunneling microscopy (STM) and field emission scanning electron microscopy (FESEM), the microporous structures on the membrane surface as well as lamellar structures in the precursors can be directly examined.The materials investigated are Celgard® polyethylene (PE) flat sheet membranes and their film precursors, both as-extruded and annealed, made at different extrusion rates (E.R.).

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Dlouhý, Jaromir, Daniela Hauserova, and Zbysek Novy. "Shape Evolution of Cementite during Accelerated Carbide Spheroidisation." Materials Science Forum 782 (April 2014): 117–22. http://dx.doi.org/10.4028/www.scientific.net/msf.782.117.

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Pearlite spheroidisation of 100CrMn6 steel was investigated. This process is well known and studied during conventional soft annealing. Presented paper describes cementite lamellae fragmentation during accelerated carbide spheroidisation. Mechanism of cementite lamellae fragmentation during conventional soft annealing depends on carbon and iron diffusion in ferrite-cementite system. On the other hand, accelerated carbide spheroidisation relies on partial pearlite austenitization and backward austenite decomposition. Aim of presented experiments was to examine shape evolution of cementite particles during transition from lamellar to globular form. Pearlite spheroidisation is normally quantified by image analysis of 2D metallographic section. Conventional metallographic observation was used for globular-lamellar particle ratio estimation. However, whole lamellae observation is necessary for spheroidisation process revelation. Ferrite matrix deep etching and cementite separation was performed to study morphological aspects of acceolerated carbide spheroidisation.

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Zhang, Qiang, Shanliang Dong, Shuai Ma, Xuwei Hou, Wenshu Yang, Yumin Zhang, and Gaohui Wu. "Microstructure and compressive behavior of lamellar Al2O3p/Al composite prepared by freeze-drying and mechanical-pressure infiltration method." Science and Engineering of Composite Materials 27, no. 1 (January 31, 2020): 1–9. http://dx.doi.org/10.1515/secm-2020-0001.

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AbstractInfiltrated molten Al matrix by mechanical-pressure infiltration method into the ceramic scaffold prepared by freeze-drying technology could prepare dense lamellar Al matrix composites without damage of the biomimetic microstructure of the scaffold. However, the investigation of lamellar Al matrix composites prepared by freeze-drying and mechanical-pressure infiltration method has not been fully understood yet. In the present work, the Al2O3 scaffold with pearl layer structure was prepared by freezing-dry method, and eventually the lamellar Al2O3p/Al composite was fabricated by mechanical-pressure infiltration method. The Al matrix was infiltrated well into the large pores of the Al2O3 scaffold, and the lamellar structure of the Al2O3 was well preserved. The hardness of the lamellar Al2O3p/Al composite was isotropic in transvers and perpendicular directions. However, the compressive strengths of the lamellar Al2O3p/Al composite were significant anisotropic while the compressive strength in transvers direction was 127.7% higher than that in the perpendicular direction, indicating the integrality of the lamellae microstructure (especially the bridging layers). Due to the mismatched deformability, weak debonding was observed between Al and Al2O3p/Al layers in the fracture surface of the lamellar Al2O3p/Al composite. It indicates that the interfacial bonding between Al and Al2O3p/Al layers is rather strong, which is beneficial for higher strength in transvers direction but lead to lower strength in perpendicular direction.

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Journal articles on the topic 'Lamellar'

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