Journal articles: 'Chemistry and microstructure'

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Lannutti, J. J. "Characterization and Control of Compact Microstructure." MRS Bulletin 22, no. 12 (December 1997): 38–44. http://dx.doi.org/10.1557/s0883769400034734.

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The microstructure and properties of a ceramic component are largely predetermined by the processes and process controls used to manufacture them. The metric for success in manufacturing is often based on gross density. For example, optimizing pressure-density response, maximizing overall density, and minimizing springback and delaminations in powder pressing all focus on characterization and control of the overall (macroscopic) state of a powder compact. Unfortunately this focus on macroscopic effects has contributed to a general neglect of the compact at the microstructural level. Process-control variables in powder compaction have been defined and discussed by many workers, but their quantitative application to predict and control compaction behavior is limited. Advances in characterization technology and computer modeling now allow us to quantitatively characterize and simulate microstructures more easily. These and other tools can help provide the scientific and technological foundation necessary to predict and control microstructure and microstructural evolution during processing.

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Ding, Qingqing, Hongbin Bei, Xinbao Zhao, Yanfei Gao, and Ze Zhang. "Processing, Microstructures and Mechanical Properties of a Ni-Based Single Crystal Superalloy." Crystals 10, no. 7 (July 3, 2020): 572. http://dx.doi.org/10.3390/cryst10070572.

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A second-generation Ni-based superalloy has been directionally solidified by using a Bridgman method, and the key processing steps have been investigated with a focus on their effects on microstructure evolution and mechanical properties. The as-grown microstructure is of a typical dendrite structure with microscopic elemental segregation during solidification. Based on the microstructural evidence and the measured phase transformation temperatures, a step-wise solution treatment procedure is designed to effectively eliminate the compositional and microstructural inhomogeneities. Consequently, the homogenized microstructure consisting of γ/γ′ phases (size of γ′ cube is ~400 nm) have been successfully produced after a two-step (solid solution and aging) treatment. The mechanical properties of the resulting alloys with desirable microstructures at room and elevated temperatures are measured by tensile tests. The strength of the alloy is comparable to commercial monocrystalline superalloys, such as DD6 and CMSX-4. The fracture modes of the alloy at various temperatures have also been studied and the corresponding deformation mechanisms are discussed.

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Xu, Wan Qiang, and Michael Ferry. "Recrystallization Behaviour of Cold Rolled Low Carbon Steel Strip with Various Starting Microstructures." Materials Science Forum 558-559 (October 2007): 419–24. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.419.

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The effect of initial microstructure (acicular ferrite (AF), polygonal ferrite (PF) and strip cast (SC)) on the recrystallization behaviour of low carbon (LC) steel was investigated. Steel strip samples (0.05 wt.% C) of 2 mm in thickness were heat treated to produce an AF and PF microstructure from coarse austenite. The AF, PF and a similar chemistry SC sample manufactured from a twin roll caster were cold rolled to 50, 70 and 90% reduction, and annealed for various times in the temperature range 580-680 °C. The evolution of microstructure during recrystallization was studied by optical microscopy and electron backscatter diffraction (EBSD) in the SEM. The initial microstructure was found to have a substantial influence on the recrystallization behavior. PF recrystallized more rapidly than AF with SC showing extremely sluggish recrystallization behaviour. The recrystallizing grains in these initial microstructures have a lognormal distribution and the recrystallized number density (grains/mm2) decreased during annealing, with the initial microstructures affecting the degree of this decrease in number density.

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Kim, Young Ho, Jeong-Woo Sohn, Youngjae Woo, Joo-Hyun Hong, Gyu Man Kim, Bong Keun Kang, and Juyoung Park. "Preparation of Microstructure Molds of Montmorillonite/Polyethylene Glycol Diacrylate and Multi-Walled Carbon Nanotube/Polyethylene Glycol Diacrylate Nanocomposites for Miniaturized Device Applications." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7860–65. http://dx.doi.org/10.1166/jnn.2015.11224.

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Environmentally friendly microstructure molds with montmorillonite (MMT) or multi-walled carbon nanotube (MWCNT) reinforced polyethylene glycol diacrylate (PEGDA) nanocomposites have been prepared for miniaturized device applications. The micropatterning of MMT/PEGDA and MWCNT/PEGDA with 0.5 to 2.0 wt% of MMTs and MWCNTs was achieved through a UV curing process with micro-patterned masks. Hexagonal dot arrays and complex patterns for microstructures of the nanocomposites were produced and characterized with an optical microscope; their thermal properties were studied by thermogravimetric analysis (TGA). The TGA results showed that these nanocomposites were thermally stable up to 350 °C. Polydimethylsiloxane thin replicas with different microstructures were prepared by a casting method using the microstructured nanocomposites as molds. It is considered that these microstructure molds of the nanocomposites can be used as microchip molds to fabricate nanobio-chips and medical diagnostic chip devices.

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Costa de Castro Santana, Jéssica Cristina, Rejane Maria Pereira da Silva, Renato Altobelli Antunes, and Sydney Ferreira Santos. "Surface Analysis, Microstructural Characterization and Local Corrosion Processes in Decarburized SAE 9254 Spring Steel." Corrosion 75, no. 12 (October 3, 2019): 1474–86. http://dx.doi.org/10.5006/3234.

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The aim of the present work was to study the surface chemistry, microstructure, and local corrosion processes at the decarburized layer of the SAE 9254 automotive spring steel. The samples were austenitized at 850°C and 900°C, and oil quenched. The microstructure was investigated using confocal laser scanning microscopy and scanning electron microscopy. The surface chemistry was analyzed by x-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess the global corrosion behavior of the decarburized samples. Scanning electrochemical microscopy was used to evaluate the influence of decarburization on the local corrosion activity. Microstructural characterization and x-ray photoelectron spectroscopy analysis indicate a dependence of the local electrochemical processes with the steel microconstituents and Si oxides in the decarburized layer.

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Ferreira-Palma, Carlos, Héctor J. Dorantes-Rosales, Víctor M. López-Hirata, and Alberto A. Torres-Castillo. "Effect of Ag additions on the microstructure and phase transformations of Zn-22Al-2Cu (wt.%) alloy." International Journal of Materials Research 112, no. 2 (February 1, 2021): 108–17. http://dx.doi.org/10.1515/ijmr-2020-8009.

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Abstract The relationship between microstructure and mechanical properties is studied for eutectoid Zn-22Al (wt.%) alloys modified with Cu and Ag. Three alloys with a Cu content of 2 wt.% and varying amounts of Ag were cast and hot-extruded. Different microstructural characteristics were induced by heat treatments: natural aging, artificial aging and furnace cooling. Structural and microstructural characterizations were carried out with X-ray diffraction and scanning electron microscopy. Mechanical properties were determined by tensile testing. Dilatometry was used for determining the effects of composition on the transformation points. The addition of Ag increased the ε phase fraction and provided solid solution strengthening, improving the mechanical strength and reducing ductility. Ag additions also displaced the eutectoid reaction to higher temperatures. The microstructure of the matrix has proven to have a strong impact on mechanical properties. The naturally aged specimens presented the highest ductility and tensile strength; however, these properties are severely affected by aging. Lamellar microstructures present the lowest ductility and values of tensile strength between those of the natural and artificially-aged specimens.

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Jurči, Peter. "Formation of Microstructure during Sub-Zero Treatments of Chromium and Chromium-Vanadium Ledeburitic Steels." Defect and Diffusion Forum 403 (September 2020): 19–36. http://dx.doi.org/10.4028/www.scientific.net/ddf.403.19.

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Despite the fact that the sub-zero treatment has widely been employed in various industrial branches more than 100 years, metallurgical principles of microstructural alterations was discovered only over past several years. Many experimental works have been done in order to describe what happens in the microstructures of various steels when they are subjected to the treatment within a temperature range 4 - 273 K and for different durations of this treatment. The obtained results infer that the changes in microstructure and thus in mechanical properties depend not only on the treatment regime used, but they are closely related to the steel chemistry. The current paper summarizes the findings obtained by sub-zero treatments of two different ledeburitic tool steels (AISI D2 and Vanadis 6). The changes in retained austenite characteristics, alterations in martensitic structures, variations in carbide characteristics and modifications in precipitation behaviour are demonstrated and discussed.

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Zhang, Yaodan, Zhijun Li, Yuanren Xiu, Chunjiang Li, Baosen Zhang, and Yu Deng. "Microstructural Characteristics of Frazil Particles and the Physical Properties of Frazil Ice in the Yellow River, China." Crystals 11, no. 6 (May 31, 2021): 617. http://dx.doi.org/10.3390/cryst11060617.

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Frazil particles, ice crystals or slushy granules that form in turbulent water, change the freezing properties of ice to create “frazil ice”. To understand the microstructural characteristics of these particles and the physical properties of frazil ice in greater depth, an in situ sampler was designed to collect frazil particles in the Yellow River. The ice crystal microstructural characteristics of the frazil particles (morphology, size, air bubble, and sediment) were observed under a microscope, and their nucleation mechanism was analyzed according to its microstructure. The physical properties of frazil ice (ice crystal microstructure, air bubble, ice density, and sediment content) were also observed. The results showed that these microstructures of frazil particles can be divided into four types: granular, dendritic, needle-like, and serrated. The size of the measured frazil particles ranged from 0.1 to 25 mm. Compared with columnar ice, the crystal microstructure of frazil ice is irregular, with a mean crystal diameter less than 5 mm extending in all directions. The crystal grain size and ice density of frazil ice are smaller than columnar ice, but the bubble and sediment content are larger.

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Nascimento, Alexandre R. C., Samantha Michelle Gateman, Janine Mauzeroll, Sylvio Savoie, Robert Schulz, and Christian Moreau. "Electrochemical Behavior, Microstructure, and Surface Chemistry of Thermal-Sprayed Stainless-Steel Coatings." Coatings 9, no. 12 (December 7, 2019): 835. http://dx.doi.org/10.3390/coatings9120835.

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Thermally sprayed stainless-steel coatings were produced with a wide range of deposition parameters. The electrochemical behavior of polished coatings was monitored for 3 weeks in 3.5 wt.% NaCl aqueous solution and compared to that of reference materials including a wrought stainless steel plate and a bulk ingot produced by arc melting of the spraying powder feedstock. Transitions in the polarization behavior are discussed based on the observed changes in coating microstructures as well as on the shifts in X-ray photoelectron spectra (XPS). Results show that the deposition parameters have a strong effect on the coating microstructures but the small differences in the polarization behavior of coatings mostly disappear after 1 week of testing. Microstructure evidence shows preferential corrosion at splats experiencing melting prior to deposition. Pitting and corrosion products between splat boundaries are also reported. XPS analysis shows that the coating surfaces are enriched in chromium oxides and hydroxides. Comparison between the coating and bulk stainless steels suggests that coating inherent defects play a major role on their impaired corrosion resistance.

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HO, P. S., R. HAIGHT, R. C. WHITE, and B. D. SILVERMAN. "CHEMISTRY AND MICROSTRUCTURE AT METAL-POLYMER INTERFACES." Le Journal de Physique Colloques 49, no. C5 (October 1988): C5–49—C5–59. http://dx.doi.org/10.1051/jphyscol:1988504.

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Cecchi-Pestellini, C., D. A. Williams, S. Viti, and S. Casu. "CHEMISTRY IN DIFFUSE CLOUDS WITH TRANSIENT MICROSTRUCTURE." Astrophysical Journal 706, no. 2 (November 11, 2009): 1429–32. http://dx.doi.org/10.1088/0004-637x/706/2/1429.

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Bachhav, Mukesh N., Nathan T. Hahn, Kevin R. Zavadil, Emily G. Nelson, Adam J. Crowe, Bart M. Bartlett, Peng-Wei Chu, Vicente J. Araullo-Peters, and Emmanuelle A. Marquis. "Microstructure and Chemistry of Electrodeposited Mg Films." Journal of The Electrochemical Society 163, no. 13 (2016): D645—D650. http://dx.doi.org/10.1149/2.0181613jes.

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Bozic, Dusan, Ivana Cvijovic, Miroljub Vilotijevic, and Milan Jovanovic. "The influence of microstructural characteristics on the mechanical properties of Ti6Al4V alloy produced by the powder metallurgy technique." Journal of the Serbian Chemical Society 71, no. 8-9 (2006): 985–92. http://dx.doi.org/10.2298/jsc0609985b.

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The influence of hot-pressing (HP-ing) parameters on the microstructure tensile properties and impact toughness of Ti6Al4V alloy produced by the powder metallurgy (PM) technique was evaluated. The experimental results show that variations in the microstructural morphology and residual porosity play an important role in affecting the mechanical properties of this alloy. The lamellar microstructure with a higher density, obtained by HP-ing above the ?-transition temperature (T?), was found to exibit a higher tensile strength and toughness than the globular microstructure produced below T?. Although both types of microstructure show a mixed fracture, the ductile mode was more pronounced in the case of the fully lamellar microstructure. By controlling the HP-ing pressure and duration time, the globular microstructure, with lower porosity, improved tensile strength and ductility in combination with a better resistance to crack initation and propagation can be obtained.

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Yang, Hongyue, Ji Qian, Ming Yang, Chunxi Li, Hengfan Li, and Songling Wang. "Study on the Effects of Microstructural Surfaces on the Attachment of Moving Microbes." Energies 13, no. 17 (August 27, 2020): 4421. http://dx.doi.org/10.3390/en13174421.

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The research of marine antifouling is mainly conducted from the aspects of chemistry, physics, and biology. In the present work, the movement model of microorganisms along or against the flow direction on the microstructural surface was established. The model of globose algae with a diameter of 5 μm in the near-wall area was simulated by computational fluid dynamics (CFD), and the fluid kinematic characteristics and shear stress distribution over different-sized microstructures and in micropits were compared. Simulation results revealed that the increase of the β value (height to width ratio) was prone to cause vortexes in micropits. In addition, the closer the low-velocity region of the vortex center to the microstructural surface, the more easily the upper fluid of the microstructure slipped in the vortex flow and reduced the microbial attachment. Moreover, the shear stress in the micropit with a height and width of 2 μm was significantly higher than those in others; thus, microbes in this micropit easily fell off.

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Höche, Nils, Eric O. Walliser, Niels J. de Winter, Rob Witbaard, and Bernd R. Schöne. "Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia)." PLOS ONE 16, no. 2 (February 26, 2021): e0247968. http://dx.doi.org/10.1371/journal.pone.0247968.

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Bivalve shells are increasingly used as archives for high-resolution paleoclimate analyses. However, there is still an urgent need for quantitative temperature proxies that work without knowledge of the water chemistry–as is required for δ18O-based paleothermometry–and can better withstand diagenetic overprint. Recently, microstructural properties have been identified as a potential candidate fulfilling these requirements. So far, only few different microstructure categories (nacreous, prismatic and crossed-lamellar) of some short-lived species have been studied in detail, and in all such studies, the size and/or shape of individual biomineral units was found to increase with water temperature. Here, we explore whether the same applies to properties of the crossed-acicular microstructure in the hinge plate of Arctica islandica, the microstructurally most uniform shell portion in this species. In order to focus solely on the effect of temperature on microstructural properties, this study uses bivalves that grew their shells under controlled temperature conditions (1, 3, 6, 9, 12 and 15°C) in the laboratory. With increasing temperature, the size of the largest individual biomineral units and the relative proportion of shell occupied by the crystalline phase increased. The size of the largest pores, a specific microstructural feature of A. islandica, whose potential role in biomineralization is discussed here, increased exponentially with culturing temperature. This study employs scanning electron microscopy in combination with automated image processing software, including an innovative machine learning–based image segmentation method. The new method greatly facilitates the recognition of microstructural entities and enables a faster and more reliable microstructural analysis than previously used techniques. Results of this study establish the new microstructural temperature proxy in the crossed-acicular microstructures of A. islandica and point to an overarching control mechanism of temperature on the micrometer-scale architecture of bivalve shells across species boundaries.

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Weiss, Laurent, Yaël Nessler, Marc Novelli, Pascal Laheurte, and Thierry Grosdidier. "On the Use of Functionally Graded Materials to Differentiate the Effects of Surface Severe Plastic Deformation, Roughness and Chemical Composition on Cell Proliferation." Metals 9, no. 12 (December 13, 2019): 1344. http://dx.doi.org/10.3390/met9121344.

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Additive manufacturing allows the manufacture of parts made of functionally graded materials (FGM) with a chemical gradient. This research work underlines that the use of FGM makes it possible to study mechanical, microstructural or biological characteristics while minimizing the number of required samples. The application of severe plastic deformation (SPD) by surface mechanical attrition treatment (SMAT) on FGM brings new insights on a major question in this field: which is the most important parameter between roughness, chemistry and microstructure modification on biocompatibility? Our study demonstrates that roughness has a large impact on adhesion while microstructure refinement plays a key role during the early stage of proliferation. After several days, chemistry is the main parameter that holds sway in the proliferation stage. With this respect, we also show that niobium has a much better biocompatibility than molybdenum when alloyed with titanium.

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Wojewoda-Budka, J., Z. Huber, L. Litynska-Dobrzynska, N. Sobczak, and P. Zieba. "Microstructure and chemistry of the SAC/ENIG interconnections." Materials Chemistry and Physics 139, no. 1 (April 2013): 276–80. http://dx.doi.org/10.1016/j.matchemphys.2013.01.035.

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Hennings, Detlev F. K., Christoph Metzmacher, and B. Seriyati Schreinemacher. "Defect Chemistry and Microstructure of Hydrothermal Barium Titanate." Journal of the American Ceramic Society 84, no. 1 (January 2001): 179–82. http://dx.doi.org/10.1111/j.1151-2916.2001.tb00627.x.

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Shallenberger, Jeffrey R. "Determination of chemistry and microstructure in SiOx (0.1." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 14, no. 3 (May 1996): 693–98. http://dx.doi.org/10.1116/1.580373.

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Hough, R. M., and S. M. Reddy. "Relating quantitative microstructure to fluid chemistry in pyrite." Geochimica et Cosmochimica Acta 70, no. 18 (August 2006): A267. http://dx.doi.org/10.1016/j.gca.2006.06.537.

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Burke, M. G., and M. K. Miller. "Understanding complex phase chemistry in a Ni-base superalloy: A combined AEM/APFIM approach." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (August 1990): 208–9. http://dx.doi.org/10.1017/s0424820100174175.

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Alloy 718 is a Nb-modified Ni-base superalloy widely-used for gas turbine and related applications which require microstructural stability and good mechanical properties at elevated temperatures (≈ 650°C). In order to achieve the desired properties, the alloy is given a multi-step thermal treatment during which a complex multiphase microstructure is developed. The primary strengthening phases in this alloy are DO22-ordered γ" and Ll2-ordered γ'. A variety of other phases such as Laves, MC-type carbides, and δ (Ni3Nb) have been observed in this material. In this study, the techniques of analytical electron microscopy (AEM) and atom probe field-ion microscopy (APFIM) have been successfully applied to characterize the microstructure of Alloy 718.The nominal bulk composition of the material examined in this investigation is listed in Table 1 together with the heat treatment schedule. Specimens for AEM characterization were examined in a Philips EM400T analytical electron microscope operated at 120kV and equipped with a Link LZ5/AN10-85S analyzer system.

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Yan, Lamei, Jianghong Yu, Yuxing Zhong, Yan Gu, Yunpeng Ma, Wenxin Li, Jia Yan, et al. "Influence of Scanning on Nano Crystalline β-Ti Alloys Fabricated by Selective Laser Melting and Their Applications in Biomedical Science." Journal of Nanoscience and Nanotechnology 20, no. 3 (March 1, 2020): 1605–12. http://dx.doi.org/10.1166/jnn.2020.17340.

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The present study focuses on the microstructural and bioactive properties evolution in selective laser melting (SLM) β titanium alloys. We have applied cross-scan strategy for improving mechanical properties and lower elastic modulus of SLMed Ti–20Mg–5Ta alloys which has been shown to be altering the microstructure and refining the grain size. The cross-scan strategy can refine the microstructure and induce various deformation textures in contrast to the conventional scan strategy. The microstructures of Ti–20Mg–5Ta alloys indicate that the cross-scan strategy will yield the best mechanical properties and lower elastic modulus. The corrosion behavior of the Ti–20Mg–5Ta alloys was studied during immersion in an acellular simulated body fluid (SBF) at 37±0.50 °C for 28 days. Both the mechanical and bioactive properties showed that the novel Ti–20Mg–5Ta alloys should be ideal for bone implants.

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Chang, Chih-Yuan. "Nonuniform Heating Method for Hot Embossing of Polymers with Multiscale Microstructures." Polymers 13, no. 3 (January 21, 2021): 337. http://dx.doi.org/10.3390/polym13030337.

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The hot embossing of polymers is one of the most popular methods for replicating high-precision structures on thermoplastic polymer substrates at the micro-/nanoscale. However, the fabrication of hybrid multiscale microstructures by using the traditional isothermal hot embossing process is challenging. Therefore, in this study, we propose a novel nonuniform heating method for the hot embossing of polymers with multiscale microstructures. In this method, a thin graphene-based heater with a nonuniform heating function, a facility that integrates the graphene-based heater and gas-assisted hot embossing, and a roll of thermoplastic film are employed. Under appropriate process conditions, multiscale polymer microstructure patterns are fabricated through a single-step hot embossing process. The quality of the multiscale microstructure patterns replicated is uniform and high. The technique has great potential for the rapid and flexible fabrication of multiscale microstructure patterns on polymer substrates.

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Schneider, Yanling, Werner Wasserbäch, Siegfried Schmauder, Zhangjian Zhou, Reiner Zielke, and Wolfgang Tillmann. "A Numerical Method to Improve the Representativeness of Real Microstructure Cut-Outs Applied in Finite Element Simulations." Crystals 11, no. 4 (April 6, 2021): 382. http://dx.doi.org/10.3390/cryst11040382.

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To improve the representativeness of a real microstructural cut-out for modeling purposes, a numerical method named as “boundary pixel color alteration (BPCA)” is presented to modify measured 2D microstructure cut-outs. Its physical background is related to the phase growth. For the application, the precondition is that the representativeness of the microstructure is already satisfied to a certain extent. This method resolves the problem that the phase composition of a small cut-out can have a large discrepancy to the real one. The main idea is to change the pixel color among neighboring pixels belonging to different phases. Our process simultaneously maintains most of the characteristics of the original morphology and is applicable for nearly all kinds of multi-phase or polycrystalline metallic alloys, as well. From our axisymmetric finite element (FE) simulations (ABAQUS ) applied with 2D real microstructures, it shows that the volume ratios of microstructural phases, as a function of the structure position to the symmetric axis, converge to phase area ratios in the 2D cut-out, even though the axisymmetric element volume is position dependent. A mathematical proof provides the reason for the aforementioned convergence. As examples to achieve real compositions and to numerically prove the aforementioned convergence, four different materials including multiphase polycrystals are implemented. An improvement of the predicted FE result is presented for the application of a modified microstructure (with a higher representativeness) compared to the original one.

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Kim, Kwangsoo, Namhyun Kang, Minjung Kang, and Cheolhee Kim. "Assessment of Heat-Affected Zone Softening of Hot-Press-Formed Steel over 2.0 GPa Tensile Strength with Bead-On-Plate Laser Welding." Applied Sciences 11, no. 13 (June 22, 2021): 5774. http://dx.doi.org/10.3390/app11135774.

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High-strength hot-press-formed (HPF) steels with a fully martensitic microstructure are being widely used in the fabrication of automotive body structure, and 2.0 GPa-strength HPF steel has recently been commercially launched. However, heat-affected zone (HAZ) softening is unavoidable in welding martensitic steel. In this study, the HAZ softening characteristic of 2.0 GPa HPF steel was investigated by applying a high-brightness laser welding process, wherein the heat input was controlled by varying the welding speed. Microstructural evaluation and hardness test results showed that the base metal with a fully martensitic microstructure was changed to the same type of fully martensitic microstructure in the weld metal, while relatively soft microstructures of tempered martensite and ferrite phase were partially formed in the intercritical HAZ (ICHAZ) and subcritical HAZ (SCHAZ) areas. In the tensile test, the joint strength was 10–20% lower than that of the base metal, and the fracture initiation was estimated at the ICHAZ/SCHAZ boundary, where the lowest hardness was confirmed by the nanoindentation technique.

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Kubair, Dhirendra V., Maxwell Pinz, Kaitlin Kollins, Craig Przybyla, and Somnath Ghosh. "Role of exterior statistics-based boundary conditions for property-based statistically equivalent representative volume elements of polydispersed elastic composites." Journal of Composite Materials 52, no. 21 (February 22, 2018): 2919–28. http://dx.doi.org/10.1177/0021998318758498.

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The property-based statistically equivalent RVE or P-SERVE has been introduced in the literature as the smallest microstructural volume element in non-uniform microstructures that has effective material properties equivalent to those of the entire microstructure. An important consideration is the application of appropriate boundary conditions for optimal property-based statistically equivalent representative volume element domains. The exterior statistics-based boundary conditions have been developed, accounting for the statistics of fiber distributions and interactions in the domain exterior to the property-based statistically equivalent representative volume element. This paper is intended to validate the efficacy of the exterior statistics-based boundary condition-based property-based statistically equivalent representative volume elements for evaluating homogenized stiffnesses of a unidirectional polymer matrix composite with a polydispersed microstructure characterized by nonuniform dispersion of carbon fibers of varying sizes in an epoxy matrix. Experimental tests and microstructural characterization of the polymer matrix composite are conducted for calibration and validation of the model. Statistically equivalent microstructural volume elements are constructed from experimental micrographs for direct numerical simulations. The performance of the property-based statistically equivalent representative volume element with exterior statistics-based boundary conditions is compared with other boundary conditions, as well as with the statistical volume elements. The tests clearly show the significant advantages of the exterior statistics-based boundary conditions in terms of accuracy of the homogenized stiffness and efficiency.

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Ogierman, Witold, and Wojciech Grzegorzek. "The influence of the WC-Co composite microstructure model on stress field heterogeneity at the microstructure level: FEM based study." Science and Engineering of Composite Materials 26, no. 1 (January 28, 2019): 134–46. http://dx.doi.org/10.1515/secm-2017-0421.

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AbstractThe paper is devoted to finite element method based study of stress field heterogeneity at microstructure level of two-phase cemented carbides. Special attention is put on investigation of influence of the microstructure model type on the stress field distributions. Two- and three-dimensional models of the microstructures have been generated. Moreover, two different representations of the microstructure have been considered. The first one assumes uniformly distributed cobalt phase forming continuous boundaries between tungsten carbide particles. The second one assumes that the cobalt phase shape and distribution are created in a way that allows for no differentiation of continuous boundaries between tungsten carbide grains. Finite element analyses have been carried out with different microstructure models. The results of the simulations are stress distributions in each phase of the material. Furthermore, a numerical homogenization has been conducted to investigate the phase properties’ influence on the effective elastic constants of the cemented carbide.

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Nasiri, Z., and H. Mirzadeh. "Spheroidization heat treatment and intercritical annealing of low carbon steel." Journal of Mining and Metallurgy, Section B: Metallurgy 55, no. 3 (2019): 405–11. http://dx.doi.org/10.2298/jmmb180813033n.

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Spheroidization annealing of low carbon steel and its effects on the microstructure and mechanical properties of dual phase (DP) steel were studied. It was revealed that the reduction in strength and hardness of the quenched martensitic microstructure was much more pronounced compared to the fully annealed ferritic-pearlitic banded microstructure with spheroidizing time. This was related to the confinement of spheroidized carbide particles to distinct bands in the latter, and the uniform dispersion of carbides and high-temperature tempering of martensite in the former. During intercritical annealing of the spheroidized microstructures, the tendency to obtain martensite particles as discrete islands was observed. This, in turn, resulted in an inferior strength-ductility balance compared to the DP steel obtained from the intercritical annealing of martensite, which negated the usefulness of the spheroidized microstructures as the initial microstructures for the processing of DP steels.

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Hopmann, Christian, and Florian Petzinka. "Use of variothermal heating for the extrusion embossing of microstructured poly(methylmethacrylate) and polycarbonate optical films." Journal of Plastic Film & Sheeting 34, no. 1 (March 20, 2017): 98–112. http://dx.doi.org/10.1177/8756087917699245.

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The importance of microstructured parts and extrudates is rising because of the increasing functional integration in many different fields of application, for example in the automotive industry and medical technology. Variothermal extrusion embossing is a continuous process that combines plastic film production with the application of large-area microstructures. The process utilizes an embossing roll and an external heating device to continuously imprint the desired structure into film during extrusion. Through this microstructuring, it is possible to integrate innovative functions into a film. Present efforts are focused on forming optical structures (micro-optics) on polycarbonate and poly(methylmethacrylate) films. This article deals with process control requirements that are necessary to successfully apply this technology, and also demonstrate how, through suitable process parameter selection, high-quality microstructures can be effectively embossed on the films. Different microstructures between 24 and 165 µm in height and between 100 and 200 µm in width are tested. With poly(methylmethacrylate) better microstructure reproduction could be achieved than with polycarbonate.

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Paumier, F., R. J. Gaboriaud, and A. R. Kaul. "Yttrium oxide thin films: chemistry- stoichiometry-strain and microstructure." Crystal Engineering 5, no. 3-4 (September 2002): 169–75. http://dx.doi.org/10.1016/s1463-0184(02)00026-6.

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Hough, R. M., and S. M. Reddy. "Relating quantitative microstructure in ore minerals to fluid chemistry." Journal of Geochemical Exploration 101, no. 1 (April 2009): 49. http://dx.doi.org/10.1016/j.gexplo.2008.12.055.

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Lumpkin, G. R., S. H. F. Leung, and J. Ferenczy. "Chemistry, microstructure, and alpha decay damage of natural brannerite." Chemical Geology 291 (January 2012): 55–68. http://dx.doi.org/10.1016/j.chemgeo.2011.09.008.

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33

Guragain, D., C. Zequine, T. Poudel, D. Neupane, R. K. Gupta, and S. R. Mishra. "Facile Synthesis of Bio-Templated Tubular Co3O4 Microstructure and Its Electrochemical Performance in Aqueous Electrolytes." Journal of Nanoscience and Nanotechnology 20, no. 5 (May 1, 2020): 3182–94. http://dx.doi.org/10.1166/jnn.2020.17414.

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Template-assisted facile synthesis of tubular Co3O4 microstructures and its electrochemical performance was studied to understand its use as a potential electrode material for supercapacitors. Tubular porous Co3O4 microstructures were synthesized using cotton fibers as bio-template. The as-obtained templated Co3O4 structure inherits the morphology and microstructure of cotton fiber. The electrochemical performance of the electrode made up of tubular Co3O4 structure was evaluated in 3 M KOH, NaOH, and LiOH aqueous electrolytes. The large-surface-area of tubular Co3O4 microstructure has a noticeable pseudocapacitive performance with a capacitance of 401 F/g at 1 A/g and 828 F/g at 2 mV/s, a Coulombic efficiency averaging ~100%, and excellent cycling stability with capacitance retention of about 80% after 5,000 cycles. Overall, the tubular Co3O4 microstructure displayed superior electrochemical performance in 3 M KOH electrolyte with peak power density reaching 5,500 W/kg and energy density exceeding 22 Wh/kg. The superior performance of tubular Co3O4 microstructure electrode is attributed to its high surface area and adequate pore volume distribution, which allows effective redox reaction and diffusion of hydrated ions. The facile synthesis method can be adapted for preparing various metal oxide microstructures for possible applications in catalysis, electrochemical, sensors, and fuel cells applications.

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Sorauf, James E., and Gregory E. Webb. "The origin and significance of zigzag microstructure in late Paleozoic Lophophyllidium (Anthozoa, Rugosa)." Journal of Paleontology 77, no. 1 (January 2003): 16–30. http://dx.doi.org/10.1017/s0022336000043389.

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In late Paleozoic solitary Rugosa, the zigzag microstructure as defined by Schindewolf (1942) is related to presence of an elevated magnesium content within biogenic calcite (intermediate magnesian calcite, IMC) and its subsequent loss during diagenesis by microdissolution and neomorphism. This particular microstructure has been recognized with certainty only in some Carboniferous and Permian rugose corals (e.g., Lophophyllidium spp.). Septal and other skeletal microstructures in those corals are dominantly (oblique) sloping-lamellar, which is also interpreted as diagenetic in origin. Two directions of oblique lamellae commonly occur in thickened skeletal elements, forming chevrons that make up zigzag microstructure with its orientation determined by presence of microdolomite blebs within skeletal calcite. Geochemical studies of corals from the Mississippian Imo Formation of Arkansas, the Pennsylvanian Buckhorn asphalt of Oklahoma and Pennsylvanian Kendrick Shale of Kentucky all indicate that magnesium content in skeletal calcite of the corals was elevated, with a maximum in the neighborhood of six to eight mole percent CaCO3, thereby forming intermediate magnesium calcite. Corals with this zigzag microstructure apparently only occurred during the late Paleozoic interval of “aragonite seas”; as a result, this diagenetic behavior of rugose corals can serve as a proxy for secular change in marine chemistry and/or climate.

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Gai, P. L., B. H. M. Billinge, and A. M. Brown. "Microstructure of carbons." Carbon 27, no. 1 (1989): 41–53. http://dx.doi.org/10.1016/0008-6223(89)90155-3.

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Janakiram, S., J. Prakash Gautam, A. Miroux, J. Moerman, and Leo Kestens. "Microstructure and Texture Control in Cold Rolled High Strength Steels." Diffusion Foundations 22 (May 2019): 84–93. http://dx.doi.org/10.4028/www.scientific.net/df.22.84.

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Formability had been important property of metals which is attributed to the texture development during thermomechanical processing particularly during hot rolling and cold rolling. In the present paper, the high strength steels with different carbon and manganese composition have been hot rolled above and below of austenite recrystallization temperature and followed by fast cooling up to different coiling temperature to get hot bands with different texture and two phase microstructure consisting ferrite with pearlite, bainite and martensite. Subsequently, these hot bands were cold rolled with 80 percent under plain strain condition. The microstructure of cold rolled sheets samples were analyzed using scanning electron microscope and showed the cold rolled microstructure with strong pancaked of two phase which was carried from the hot rolling. Cold rolled texture in ferrite pearlite microstructure is completely replaced by new texture components from hot rolled condition without the effect of Tnr. Hot rolled texture was retained in ferrite-bainite and martensite microstructure with the effect of Tnr. Increase in alloy chemistry weakens the texture intensity in ferrite pearlite/bainite microstructure. Whereas increase in alloy chemistry strengthens the texture intensity in ferrite martensite microstructure.

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Sahu, Bibhuti Bhusan, Yongyi Yin, Sven Gauter, Jeon Geon Han, and Holger Kersten. "Plasma engineering of silicon quantum dots and their properties through energy deposition and chemistry." Physical Chemistry Chemical Physics 18, no. 37 (2016): 25837–51. http://dx.doi.org/10.1039/c6cp05647d.

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Liu, Dong Sheng, Matthias Militzer, and Warren J. Poole. "Microstructure Model for a Dual-Phase Steel." Materials Science Forum 539-543 (March 2007): 4391–96. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4391.

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The microstructural evolution has been studied for hot rolling of a dual-phase steel with a lean C-Mn-Si chemistry. This study includes the investigation of austenite grain growth during reheating, constitutive behaviour and static recrystallization kinetics of austenite, and austenite decomposition during simulated run-out table cooling conditions. To develop and validate the microstructure models for these phenomena, experimental studies have been carried out in the laboratory using a Gleeble 3500 thermomechanical simulator. The hyperbolic sine relationship between flow stress and Zener-Hollomon parameter is employed to describe the constitutive behaviour. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory is used to predict the static recrystallization kinetics. Ferrite transformation start is described with an approach that considers early growth of corner nucleated ferrite. The fraction of ferrite transformed from austenite during continuous cooling is described using the JMAK approach in combination with the additivity rule. The ferrite grain size is quantified as a function of the transformation start temperature. The overall microstructure model has been validated based on a number of laboratory simulations of the entire hot strip rolling and controlled cooling process with an emphasis on industrially relevant run-out table cooling strategies.

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Koh, S. U., J. S. Kim, B. Y. Yang, and K. Y. Kim. "Effect of Line Pipe Steel Microstructure on Susceptibility to Sulfide Stress Cracking." Corrosion 60, no. 3 (March 1, 2004): 244–53. http://dx.doi.org/10.5006/1.3287728.

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Abstract The purpose of this experiment was to evaluate the effect of microstructure on sulfide stress cracking (SSC) properties of line pipe steel. Different kinds of microstructures, with chemical compositions identical to one steel heat, were produced by various thermomechanically controlled processes (TMCP). Coarse ferrite-pearlite, fine ferrite-pearlite, ferrite-acicular ferrite, and ferrite-bainite microstructures were investigated with respect to corrosion properties, hydrogen diffusion, and SSC behavior. SSC was evaluated using a constant elongation rate test (CERT) in a NACE TM0177 solution (5% sodium chloride [NaCl] + 0.5% acetic acid [CH3COOH], saturated with hydrogen sulfide [H2S]). The corrosion properties of steels were evaluated by potentiodynamic and linear polarization methods. Hydrogen diffusion through steel matrix was measured by an electrochemical method using a Devanathan-Stachurski cell. The effect of microstructure on cracking behavior also was investigated with respect to crack nucleation and propagation processes. Test results showed that ferrite-acicular ferrite microstructure had the highest resistance to SSC, whereas ferrite-bainitic and coarse ferritie-pearlitic microstructures had the lowest resistance. The high susceptibility to SSC inferritie-bainitic and coarse ferritic-pearlitic microstructures resulted from crack nucleation on hard phases such as grain boundary cementite in coarse ferritie-pearlitic microstructures and martensite/retained austenite (M/A) island in bainitic phases. Hard phase cementite at grain boundaries or M/A constituent in bainitic phases acted as crack nucleation sites and could be cracked easily under external stress; consequently, the susceptibility of steel to SSC increased. Metallurgical parameters including matrix structure and defects such as grain boundary carbides and inter-lath M/A constituents were more critical parameters for controlling SSC than the hydrogen diffusion rate.

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Różański, Adrian, Magdalena Rajczakowska, and Andrzej Serwicki. "The influence of microstructure geometry on the scale effect in mechanical behaviour of heterogeneous materials." Science and Engineering of Composite Materials 24, no. 4 (July 26, 2017): 557–71. http://dx.doi.org/10.1515/secm-2015-0007.

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AbstractThere are a significant number of factors which have impact on the scale effect in the mechanical behaviour of composite materials. In this paper, the influence of the microstructure on this phenomenon is examined. In particular, how the results of the uniaxial compression test are affected by the microstructure geometry is verified. For the purposes of this study, two different materials are chosen, i.e. pure gypsum and mortar. Firstly, the microstructures of the two considered materials are compared with the use of different microstructure measures, i.e. attenuation profiles, porosity and pore size distributions, calculated based on the images obtained from the X-ray microCT. Then, a series of uniaxial compression tests is performed for a large number of cylindrical specimens made of the two materials under study. Four different sample diameters are assumed in order to investigate the size effect in the considered composites. For both materials, the results of uniaxial compressive strength and the Young modulus are presented. The relationship between the microstructure of the material and the scale effect in mechanical properties is proved. The scale effect is more demonstrable in the case of the material which exhibits a more heterogeneous microstructure.

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Marshall, Kenneth P., Sigurd O. Eidem, Didrik R. Småbråten, Sverre M. Selbach, Tor Grande, and Mari-Ann Einarsrud. "Hydrothermal synthesis of hexagonal YMnO3 and YbMnO3 below 250 °C." Dalton Transactions 50, no. 28 (2021): 9904–13. http://dx.doi.org/10.1039/d1dt01572a.

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Yanlong, Zhao, Bai Jitao, Liang Jiahe, and Simiao Zhang. "Analysis of chemical structure and characteristics of building materials based on element chemistry." E3S Web of Conferences 248 (2021): 01028. http://dx.doi.org/10.1051/e3sconf/202124801028.

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Elements in accordance with a certain proportion and spatial arrangement constitute the microstructure of the building materials, which lead to a specific property and function in the macro. From the perspective of element chemistry, we divide common building materials into three categories: silicon-based building materials, carbon-based building materials and iron-based building materials. Then, with the knowledge of valence electron structure and electronic configuration, we systematically expound the three-element building materials system. According to that division mode, we explain the microstructural causes and macroscopic properties of the three-element building materials system through the valence bond theory, so as to provide references for the development and application of building materials.

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Zhang, Guo Qing, Zhou Li, Zhong Wu Liu, Zhi Hui Zhang, Yifei Zhang, Hua Yuan, Rui Ping Yao, Shibin Xu, Shi Fan Tian, and Ming Gao Yan. "Spray Forming and Thermal Processing for High Performance Superalloys." Materials Science Forum 475-479 (January 2005): 2773–78. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2773.

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A unique pilot low-pressure spray forming plant was established and its spray atomisation and deposition process developed to study the new processing methods for high performance materials and to develop spray forming technology suitable for making sound superalloy preforms. The results indicated that high density (>99%) preforms (billets and rings) with little gas pick-ups and with the microstructural features of rapidly solidified superalloys, i.e. refined equiaxed grains and uniform microstructure, could be achieved after the optimisation of the spray atomisation and deposition process. The effects of subsequent thermal processing on the density, microstructure and mechanical properties of the spray formed superalloy were investigated. Compared to the turbine disks and rings made by wrought superalloys, the spray formed superalloys with identical chemistry showed significantly improved metallurgical quality, higher mechanical properties, and better hot workability.

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Li, Xiucheng, Jingxiao Zhao, Lili Dong, R. Devesh Kumar Misra, Xuemin Wang, Xuelin Wang, and Chengjia Shang. "The Significance of Coherent Transformation on Grain Refinement and Consequent Enhancement in Toughness." Materials 13, no. 22 (November 12, 2020): 5095. http://dx.doi.org/10.3390/ma13225095.

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Coherent transformation is considered to be an effective approach to refine the microstructure and enhance toughness of structural steels. However, there are gaps in the knowledge on the key aspects of microstructure that govern toughness. In this regard, a low alloyed experimental steel with lean chemistry was subjected to a simple heat treatment involving austenitization at different temperatures, followed by quenching and tempering to obtain bainitic microstructures with different boundary composition. The microstructure of the four experimental steels was characterized by electron backscattered diffraction and mechanical properties were determined. The study indicated that the density of high angle grain boundaries does not adequately reflect the change of ductile-to-brittle transition temperatures (DBTT) of the experimental steels. Thus, we propose here a new mechanism on reducing DBTT from the perspective of misorientation of boundary, which takes into consideration these aspects in defining DBTT. One is inhibition effect on cleavage fracture by boundaries with high {100}-plane misorientation angles, and the other is ductility improvement by boundaries with high {110}-plane misorientation angles. Furthermore, the contribution of prior austenite grain boundary, packet boundary, block boundary, and sub-block boundary on toughness is also analyzed.

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Pataric, Aleksandra, Marija Mihailovic, Branislav Markovic, Miroslav Sokic, Andreja Radovanovic, and Branka Jordovic. "Microstructure as an essential aspect of EN AW 7075 aluminum alloy quality influenced by electromagnetic field during continuous casting process." Chemical Industry 75, no. 1 (2021): 31–37. http://dx.doi.org/10.2298/hemind201214006p.

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Microstructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA).

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El-Bagoury, Nader, Sameh I. Ahmed, Ola Ahmed Abu Ali, Shimaa El-Hadad, Ahmed M. Fallatah, G. A. M. Mersal, Mohamed M. Ibrahim, et al. "The Influence of Microstructure on the Passive Layer Chemistry and Corrosion Resistance for Some Titanium-Based Alloys." Materials 12, no. 8 (April 15, 2019): 1233. http://dx.doi.org/10.3390/ma12081233.

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The effect of microstructure and chemistry on the kinetics of passive layer growth and passivity breakdown of some Ti-based alloys, namely Ti-6Al-4V, Ti-6Al-7Nb and TC21 alloys, was studied. The rate of pitting corrosion was evaluated using cyclic polarization measurements. Chronoamperometry was applied to assess the passive layer growth kinetics and breakdown. Microstructure influence on the uniform corrosion rate of these alloys was also investigated employing dynamic electrochemical impedance spectroscopy (DEIS). Corrosion studies were performed in 0.9% NaCl solution at 37 °C, and the obtained results were compared with ultrapure Ti (99.99%). The different phases of the microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Chemical composition and chemistry of the corroded surfaces were studied using X-ray photoelectron spectroscopy (XPS) analysis. For all studied alloys, the microstructure consisted of α matrix, which was strengthened by β phase. The highest and the lowest values of the β phase’s volume fraction were recorded for TC21 and Ti-Al-Nb alloys, respectively. The susceptibility of the investigated alloys toward pitting corrosion was enhanced following the sequence: Ti-6Al-7Nb < Ti-6Al-4V << TC21. Ti-6Al-7Nb alloy recorded the lowest pitting corrosion resistance (Rpit) among studied alloys, approaching that of pure Ti. The obvious changes in the microstructure of these alloys, together with XPS findings, were adopted to interpret the pronounced variation in the corrosion behavior of these materials.

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Baker, Ian. "Microstructural characterization of snow, firn and ice." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2146 (April 15, 2019): 20180162. http://dx.doi.org/10.1098/rsta.2018.0162.

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This paper provides an overview of techniques used to characterize the microstructure of snow, firn and ice. These range from traditional optical microscopy techniques such as examining thin sections between crossed polarizers to various electron-optical and X-ray techniques. Techniques that could have an impact on microstructural characterization of snow, firn and ice in the future are briefly outlined. This article is part of the theme issue ‘The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets’.

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Berestok, Taisiia, Pablo Guardia, Javier Blanco Portals, Sònia Estradé, Jordi Llorca, Francesca Peiró, Andreu Cabot, and Stephanie L. Brock. "Surface Chemistry and Nano-/Microstructure Engineering on Photocatalytic In2S3 Nanocrystals." Langmuir 34, no. 22 (May 11, 2018): 6470–79. http://dx.doi.org/10.1021/acs.langmuir.8b00406.

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Humphreys, E. S., P. J. Warren, J. M. Titchmarsh, and A. Cerezo. "Microstructure and chemistry of Al–V–Fe–Si nanoquasicrystalline alloys." Materials Science and Engineering: A 304-306 (May 2001): 844–48. http://dx.doi.org/10.1016/s0921-5093(00)01580-x.

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Natali Sora, I., R. Pelosato, D. Botta, and G. Dotelli. "Chemistry and microstructure of cement pastes admixed with organic liquids." Journal of the European Ceramic Society 22, no. 9-10 (September 2002): 1463–73. http://dx.doi.org/10.1016/s0955-2219(01)00473-3.

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Journal articles on the topic 'Chemistry and microstructure'

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