Phase Inclusions Research Articles

Phase distribution and properties identification of heterogeneous materials: A data-driven approach

This paper presents a new methodology to extend the Data-Driven Identification (DDI) to heterogeneous samples made of multiple elastic materials. By using the Correspondence Analysis (CA) technique to post-process DDI, we are able to identify multiple material databases representative of the material behavior of each phase. Simultaneously, we localize the different phases (matrix and inclusions) in the sample. For different contrasts between phases, the method is tested on synthetically generated data and a parametric study is performed. Furthermore, we show that it is possible to iterate between DDI and CA in order to improve the method’s predictions when it is limited by scarce input data. In all the cases studied, the methodology proves to be effective for estimating stresses, as well as for identifying the different phases in the sample.

Influence of the cavity size of cyclodextrins on the photochromism of azoimidazoles

1-Alkyl-2-(arylazo)imidazole (RaaiR/) exists in trans configuration about the –NN- bond. Upon optical excitation in UV region the trans-configuration isomerises to cis-RaaiR/. The photochromism is very susceptible to internal substituents and external environment like solvent polarity, viscosity and presence of innocent foreign species. In this work, the trans-to-cis photoisomerisation of RaaiR/has been studied in DMF solution of cyclodextrin (α/β/γ-CD). The rate of trans-to-cis isomerisation is decreased in presence of CD compared to native form of RaaiR/. The quantum yield of the photoisomerisation is decreased by 35–55% in inclusion phase, CD@RaaiR/, than free photochrome and follows the rate sequence: free state > γ-cyclodextrin > β-cyclodextrin > α-cyclodextrin. The cis-to-trans isomerisation proceeds slowly in visible light irradiation while it is appreciably fast with increasing temperature. The activation energy (Ea) of cis → trans thermal isomerisation is also diminished compared to free state of photochrome. The absorption spectral studies have been used in case of Pai-C18H37 with β-CD and inclusion constant is Kb ​= ​0. 121 M−1. The 1H NMR spectral measurement also suggests interaction of aryl protons with cavity protons of β-CD. DFT computation is also attempted to examine the inclusion of RaaiR/with CD and the negative values of binding energy show that the process of inclusion is spontaneous and complexes formed are stable.

Magnetics Hysteresis Properties and Microstructure of High-Energy (Nd,Dy)\u2013Fe\u2013B Magnets with Low Oxygen Content

Magnetic properties and microstructure of high-energy (Nd,Dy)–Fe–B magnets with Dy of no more than 1 wt % prepared via a low-oxygen routine are studied. Oxygen content in magnets does not exceed 0.20 wt %. 0.5 wt %–Dy addition reliably stabilizes the coercivity MHc higher than 13 kOe; in this case, the maximum energy density product (BH)max of magnets is 48.5–49.5 MG Oe. High magnetic hysteresis properties are gained via optimization of chemical and phase compositions of magnets, as well as their microstructure. The grain size of the main Nd2Fe14B phase is approximately 3.5 μm; and according to X-ray analysis, the weight fraction of additional Nd-rich phases (NdOx and Nd2O3) does not exceed 2.5%. Scanning electron microscopy study has demonstrated that in triple junctions of Nd2Fe14B grains there are two types of inclusions (В and С) of the NdOx phase, which significantly differ by their chemical composition. С-phase inclusions with low oxygen content (х ≈ 0.03) are enriched in Fe (40–50 wt %); whereas, В-phase with high oxygen content (х ≈ 0.70) contains 3–5 times less Fe. The angular dependences of coercivity of (Nd,Dy)–Fe–B magnets are presented.

Composition Materials With Metal Matrix Condensed from the Vapor Phase

In this article, the present-day problems of microporous condensed materials obtained from the vapor phase are discussed. The pore sizes are regulated by the amount of the second phase concentration and the deposition temperature.
 The oxides, fluorides, and sulfides can be used as the second phase and non-removable inclusions. The open porosity can be regulated from 0% to 50 %of the porosity and with average porose sizes of 0.1 to 8 µm. The condensed micro-porous materials can be deposited in coating form or the form of massive bulk sheet materials with a thickness of up to 6 mm and a diameter of 1m.

Analysis of thermal stresses in FGM-Matrix medium induced by constant heat flux at the far field

The thermal stress due to heat flux at the far field is derived for an infinitely extended elastic medium which contains a spherical inclusion made of functionally graded materials (FGM). The material properties in the inclusion phase are assumed to vary linearly while the material properties in the matrix phase are uniform. As FEM is not appropriate for this type of analysis, a semi-analytical approach is employed in which the temperature distribution for the entire medium and the thermal stress field in the matrix phase are obtained analytically while the thermal stress field in the FGM phase is obtained semi-analytically by solving a set of ordinary differential equations. The present method is preferred over FEM in that all the geometric and material parameters are kept in the formulations and the cost of computation is minimal. The von Mises stress is shown to be continuous at the FGM-matrix interface which underscores the advantage of using FGMs over conventional composites.

Production of high thermal conducting aluminum-graphite
 composite materials by the press-squeeze method utilizing porous graphite preforms and aluminum alloys

Consideration is given to the technological process of producing high thermal conducting
 aluminum-graphite composite materials by press-squeeze method utilizing porous graphite preforms and aluminum alloys. It is shown that the rate of press-squeeze process, aluminum alloy
 composition provide dense, defect-free and non-porous thermal interface between graphite and matrix alloy, it is noted the absence of crystal inclusions of third phases, such as SiC, Al4C3.
 An example of evaluation of thermal conductivity of the sample of composite material is given with consideration of graphite particles orientation and matrix-filler thermal interface heat
 conductivity.

An improved gas extraction model during stepwise crushing: New perspectives on fluid geochronology and geochemistry

Trapped fossil fluids in mineral-hosted fluid inclusions preserve pivotal information on the evolution of paleo geological systems, particularly the hydrothermal mineralization systems. However, identification of the sources of the extracted gases during bulk analysis of fluid inclusions is challenging because multiple generations, types, and phases of fluid inclusions may exist in the same mineral. To better identify the gas sources during stepwise crushing we report an improved gas extraction model of fluid inclusions. Stepwise extracted gases from fluid inclusions in quartz and cassiterite were measured with a quadrupole mass spectrometer and compared with Raman analysis of different types of secondary (SFIs) and primary (PFIs) fluid inclusions. We found that H2O-poor and CO2-rich gases with elevated CO2/CH4 ratios, H2O and formamide-rich gases, and CH4-rich gases were extracted sequentially during stepwise crushing. Such compositional variations of the released gases suggest that the extraction of fluid inclusions starts from SFIs with high vapor-filling degrees (f) and CO2-bearing tri-phase high-f fluid inclusions, which is followed by large liquid-rich SFIs and mid-sized high-f PFIs that are rich in CO2 and formamide, and ends with small CH4-rich low-f PFIs. These findings suggest that the degassing pattern of hydrothermal minerals during stepwise crushing is mostly governed by the physicochemical characteristics of the fluid inclusions, in particular, their vapor-filling degrees, sizes, compositions (which can lead to different inner pressures and densities), and associations with micro-cracks. This updated model of gas release patterns strengthens the theoretical basis for differentiating and identifying the sources of gases extracted during stepwise crushing experiments, which is key to understanding the fluid geochronology and geochemistry of hydrothermal deposits with multi-stage hydrothermal evolution in general.

Extrinsic Anisotropy of Two-Phase Newtonian Aggregates: Fabric Characterization and Parameterization.

Rocks of the Earth's crust and mantle commonly consist of different minerals with contrasting mechanical properties. During progressive, high‐temperature (ductile) deformation, these rocks develop extrinsic mechanical anisotropy linked to strain partitioning between different minerals, amount of accumulated strain, and bulk strain geometry. Extrinsic anisotropy plays an important role in a wide range of geodynamic processes up to the scale of mantle convection. However, the evolution of grain‐ and rock‐scale fabrics causing this anisotropy cannot be directly simulated in large‐scale numerical simulations. For two‐phase aggregates–a good rheological approximation of most Earth's rocks–we propose a method to indirectly approximate the extrinsic viscous anisotropy by combining (a) 3D mechanical models of rock fabrics, and (b) analytical effective medium theories. Our results confirm that weak inclusions induce substantial weakening by forming a network of weak thin layers with limited lateral connectivity. Consequently, even when the inclusion phase is extremely weak, structural weakening is not larger than 30–60%, less than in previous estimates. On the other hand, the presence of strong inclusions does not have a profound impact on the effective strength of the aggregate, and lineated fabrics only develop at relatively low viscosity contrasts. When rigid inclusions become clogged, however, the aggregate viscosity can increase over the theoretical upper bound. We show that the modeled grain‐scale fabrics can be parameterized as a function of the bulk deformation and material phase properties and combined with analytical solutions to approximate the anisotropic viscous tensor.

Modification of steel surface layer by electroslag surfacing using compounds with high melting point

The authors have studied the effect of alloying on the structure, microhardness and abrasive wear resistance of electroslag surfacing layers on low-alloy structural steel 09G2S. For modification, mixtures of Si3 N4 + FeSi2 + Si powders obtained in the Department of Structural Macrokinetics of the Tomsk Scientific Centre SB RAS by the method of SHS synthesis, as well as powder compositions based on TiC, were used. A molten electrode was made of low-alloy steel St3, on which modifying compositions Si3 N4 + FeSi2 + Si were poured out, in the first case, and modifying compositions Si3 N4 + FeSi2 + Si, located below, in the second case. Metallography and X-ray microanalysis methods were used to determine the structure and to analyze the composition of the deposited layers, heat-affected zone (HAZ) and the base metal, on the basis of which assumptions were made about the nature of the formation of coating properties – hardness and wear resistance. It is shown that the main influence on the wear resistance is exerted by structure of the surfacing metal. There is a positive effect of modifying coatings by alloying materials with the alloys Si3 N4 + FeSi2 + Si + St3 and TiC + St3. In the molten layer, many new crystallization centers are released in the form of dispersed TiC particles. Dispersed TiC particles with a high melting point (3180 °C) are the first to fall out of the melt and not only serve as multiple crystallization centers, but also prevent the growth of austenitic grains, which ensures the formation of dispersed structure. The coatings contain TiC carbide particles, as well as inclusions of other phases. At the same time, an increase in hardness of the deposited layer containing titanium carbide inclusions is observed in direction of the boundary with the base. Wear resistance of the layer increases when a TiC-based coating is formed. The obtained data can be used to create deposited layers on the metal surface with high resistance against abrasive wear.

Structural, optical and magnetic properties of stencil-free printed ZnO layers doped with Fe2+ and Fe3+ ions

In this paper we investigate the doping effect of FeO and Fe2 O3 on the structural, optical and magnetic properties of ZnO layers prepared by a new stencil-free technique. Samples were characterized by X-ray diffraction (XRD), atom force and magnetic force microscopy, photoluminescence and Raman spectroscopy. A quite high quality of the printed Fe-doped ZnO layers was demonstrated. It was shown that the incorporated Fe2+ or Fe3+ ions substitute Zn2+ ions in ZnO lattice and, unlike the doped layers prepared by other technological methods, were uniformly distributed in the Zn2+ sites. The levels of doping with different impurities that make it possible to obtain layers free of second phase inclusions were established. The printed ZnO:Fe layers illustrated pronounced ferromagnetic behavior at ambient conditions. The values of the magnetic field correlated with the impurity content. The value of magnetization of the ZnO:Fe3+ layers was shown to be approximately twice that of the printed ZnO:Fe2+ layers. At the same time, magnetization of ZnO:Fe2+ layers was approximately the same as of the printed ZnO:Co2+ and ZnO:Mn2+ layers studied by us previously. The higher magnetization observed in ZnO:Fe3+ layers was supposed to be due to the carrier-mediated mechanism of magnetization in these layers.

Deformation mechanism of bimodal nanotwinned Cu-Ag alloy with grain boundary affect zone segregation

The deformation mechanism of bimodal nanotwinned (NT) Cu-Ag alloys with grain boundary affect zone (GBAZ) segregation has been investigated through molecular dynamics (MD) simulations. The bimodal NT Cu-Ag alloys model is established by embedding a coarse NT grain into the ultrafine grained matrix. The solute Ag atoms in Cu-Ag alloy polycrystalline matrix are segregated in the GBAZ (generated by equidistance scaling method). The coarse NT grain inclusion phase can impart high strength resulting from the twin boundaries (TB) strengthening regime. Through the uniaxial tensile simulations, the strength of bimodal NT samples is found to be related with the three factors, including coarse NT grain size, TB inclination angles as well as TB spacings (TBSs). The dislocation activities and corresponding deformation mechanisms are explored in detail.

THE LEVEL OF PLASTICITY OF THE PHASES IN NON-METALLIC INCLUSIONS WITH A COMPLEX STRUCTURE

Purpose. It is necessary to study of the effect of heterophase inclusions on the technological ductility of steels for various purposes. The goal of the work was to study of the nature and level of plasticity of multiphase inclusions in steels under conditions of hot and cold deformation. Methods. Comprehensive methods for the study of heterophase non-metallic inclusions (metallographic, petrographic, X-ray microanalysis methods) were used. Results. Plastic phases in multiphase inclusions of different types under conditions of hot and cold deformation of steels were investigated. It is shown that each type of multiphase inclusions, which are microcomposite formations in steels, is characterized by its laws of development of deformation processes, which are determined by their chemical and phase composition, structure, deformation ability of the phases of inclusions. Scientific novelty. Peculiarities of plastic behavior of multiphase inclusions of different types are established. The inhibitory effect of non-deformable phases of inclusions on the deformability of plastic phases in a wide range of steel deformation temperatures is established. Peculiarities of the nature of plasticity of multiphase inclusions having different compositions and structure are discussed. Practical significance. Using the results obtained will allow developing technologies for producing steels with regulated content and types of multiphase non-metallic inclusions, which will significantly increase their technological plasticity, as well as prevent the formation of various kinds of defects during the processing of steels by pressure.

Effect of ZrB2 Functionalized Nanoparticles Growth on Microstructural and Corrosion Resistance on Mild Steel through Electrodeposition Route

In other to have a better performance of Ni-P-Zn multifunctional applications, crystallite-like Ni-P-Zn-ZrB2 composite was actively fabricated by electrodeposition principle. The corrosion, structural evolution and surface active phenomena were investigated by various techniques. The influence of ZrB2 particulate on the morphology and corrosion properties was examined. The outcomes show an inclusive flower-like doped ZrB2 phase constituent and is uniformly distributed Ni-P-Zn-ZrB2 improved strengthening effect. The corrosion progression of the developed metal alloy was compared with other coating matrix from 10-25 minutes interval. The integration of ZrB2 on Ni-P-Zn phase especially for 25 min deposits significantly enhances corrosion resistance due to good grain refinement. Keywords: Ni-based composite, electrodeposition, time difference, coating, corrosion

LA-ICP-MS and TEM constraints on the magmatic and post-magmatic processes recorded by the zircon-xenotime intergrowth in pegmatite (Piława Górna, Góry Sowie Block, SW Poland)

A strongly altered zircon-xenotime intergrowth in pegmatite from the Piława Górna (the Góry Sowie Block, SW Poland) was studied with transmission electron microscopy (TEM) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Distinct domains demonstrate features related to fluid-induced coupled dissolution-reprecipitation processes resulting in microscale to nanoscale porosity in the zircon and in xenotime, and diffusion-reaction processes in the metamict core of the zircon. The inclusions of secondary phases include fluorapatite, unknown layered Fe-silicate, fibrous Fe-oxides, solid solutions of coffinite-thorite and uraninite-thorianite, uraninite and secondary U-rich zircon. The fluid had high concentrations of Ca and Fe, transporting these nonformula elements through the zircon and xenotime structure while mobilizing U, Th and Pb even in robust xenotime, thus forming small inclusions in nanopores. Nanoinclusions of galena in the zircon represent major Pb mobilization that may cause disturbance during UPb geochronological analysis. The trace element composition of zircon matches patterns typical of altered zircon. The differentiation of geochemical characteristics between the metamict core and the altered rim of zircon implies different alteration mechanisms, with a stronger role of fluids in the alteration of the rim. Nanoscale observations complement trace element microanalysis and serve as an important and necessary tool to further understand the alterations of geochronometers in the presence of alkaline-rich fluid, especially in the complex environments of pegmatites.

The Accumulation Characteristics of the Paleozoic Reservoir in the Central-Southern Ordos Basin Recorded by Organic Inclusions

The Permian tight clastic reservoir and Ordovician carbonate reservoir were developed in the central-southern Ordos Basin. This study investigated the fluid inclusion petrography, diagenetic fluid characteristics, formation process of natural gas reservoir, source rock characteristics, and reservoir accumulation characteristics of these Paleozoic strata by petrographic observations, scanning electron microscope imaging, fluid inclusion homogenization temperature, salinity, laser Raman spectrum, and gas chromatograph analyses. The results have suggested two phases of fluid inclusions in both the Permian sandstone and the Ordovician Majiagou Formation dolomite reservoirs, and the fluid inclusions recorded the history from the early thermal evolution of hydrocarbon generation to the formation, migration, and accumulation of natural gas. The early-phase inclusions show weak yellow fluorescence and recorded the early formation of liquid hydrocarbons, while the late-phase inclusions are nonfluorescent natural gas inclusions distributed in the late tectonic fractures and recorded the late accumulation of natural gas. The brine systems of the Permian and Ordovician fluid inclusions are, respectively, dominated by CaCl2-H2O and MgCl2-NaCl-H2O. The diagenetic fluids were in the ranges of medium-low temperature and moderate-low salinity. The natural gas hydrocarbon source rocks in the Ordos Basin include both the Permian coal-bearing rocks and the Ordovician carbonates. The process of the early-phase liquid hydrocarbon formation and migration into the reservoir corresponded to 220 Ma (Late Triassic). The late large-scale migration and accumulation of natural gas occurred at 100 Ma (early Late Cretaceous), which was close to the inclusion Rb/Sr isochron age of 89.18 Ma, indicating that the natural gas accumulation was related to the Yanshanian tectonic movement.

Statistical damage constitutive model based on self‐consistent Eshelby method for natural gas hydrate sediments

AbstractNatural gas hydrate (NGH) is widely distributed in marine sediments and continental permafrost, which is a promising energy resource. The sustainable and safe exploration and production of NGH requires fully understanding of its mechanical behaviors, which is still a challenge to our community. In this paper, a statistical damage constitutive model named SC‐SDCM is developed for NGH sediments. The NGH sediments are regarded as two phases: the matrix phase of solid mineral grains, pore fluid, and gas, and the inclusion phase of hydrate crystal. The effective elastic parameters of such two‐phase composite are estimated by self‐consistent method (SC) according to the equivalent inclusion principle of micromechanics. The mesoscopic element strength of the NGH sediments is described by the Weibull statistical distribution and the damage theory of composite materials. And then combined with the Drucker‐Prager failure criterion of microelement, the damage constitutive model of NGH sediments is established. The new SC‐SDCM is tested to be reliable and robust by triaxial experimental observations on artificial cores and naturally occurring samples under different confining pressures and hydrate saturations. The SC‐SDCM could properly describe the stiffness, peak strength, and strain softening properties of the NGH sediments. Moreover, the predictions of SC‐SDCM are closest to the experiment observations compared to several published constitutive models, especially for the near‐ and after‐damage stages with relatively high hydrate saturation.

Resonance of mixing energy and energy of elastic deformations during spinodal decomposition and the composition modulation effect in ZnхCd1-ХTe solid solutions

The Cahn-Hilliard equation is adapted to consider the spinodal decomposition of A2B6 semiconductor solid solutions. This approach is used to analyze the process of spinodal decomposition of ZnхCd1-хTe solid solution, which is accompanied by the appearance of the composition modulation effect during its low-temperature synthesis. Numerical simulations of the spinodal decomposition of the ZnхCd1-хTe solid solution are performed. It is shown that micro-variations of the material composition are related by the resonance phenomenon between the excess mixing energy and the energy of elastic strains arising in the inclusions of the new phase, which are coherently conjugated with the initial crystal lattice. It is revealed that such resonance phenomena are most intense when the conditions for the material synthesis are located in close proximity to the spinodal curves on the phase state diagram of the system.

Motivational, Emotional, and Social Factors Explain Academic Achievement in Children Aged 6–12 Years: A Meta-Analysis

Recent studies highlight the effect of cognitive factors on academic achievement, ignoring motivational, emotional, and social factors. This provides the background for the present study, a meta-analysis on the relationship between academic achievement and motivational factors (motivation, self-concept, and self-esteem), emotional factors (emotional intelligence, emotional competence, and emotional well-being), and social factors (social intelligence, social competence, and social skills) in children aged 6–12 years (37 samples, n = 15,777). The methodology based on the PRISMA protocols was applied: phases of inclusion and exclusion of articles, analysis of effect size, heterogeneity, publication bias, and, finally, meta-regressions and moderation analysis. The results showed a moderate positive effect size (0.321) for motivational and social factors (0.210) and a small positive effect size (0.172) for emotional factors. The moderating effects of age (65% on social factors) and geographical area (52% on motivational factors, 17% on emotional factors, and 76% on social factors) were studied. These results highlight the importance of motivational and social factors regarding academic achievement. In addition, along with the moderating effect of age, that of geographical area emerges strongly given the diversity of contexts studied. Our results highlight the importance that these factors have on academic performance and, therefore, the need to design school plans that address the correct development of these variables.

Inclusion Characteristic of Blue Sapphire from Australia

The main purpose of this study is to observe the abundant inclusions of blue sapphire samples from Australia and analyze the composition of inclusions and provide a theoretical basis for the identification of its origin.The Leica M205A microscopic camera was used to finish the image acquisition of characteristic inclusions in blue sapphires from Australia. Laser Raman spectrometer was used to test inclusion composition.The result showed that the sapphire samples generally had obvious uneven colour distributions, healing fissures and partings. Some samples have hexagonal ribbons. Microscopic observation showed solid phase inclusions, tubular gas-liquid inclusions, fingerprint inclusions, and occasionally three-phase inclusions.Specially, some inclusions occur in the form of bicrystals.The inclusions identified by Raman spectroscopy include zircon, rutile, anatase, hematite, niobite, nepheline and CO2.

Effect of Melt Overheating on Structure and Mechanical Properties of Al-Mg-Si Cast Alloy

The paper discusses the complex effect of melt overheating with subsequent fast cooling down to the pouring temperature on the crystallization process, microstructure and mechanical properties of Al-Mg-Si aluminum alloy. The results obtained facilitated the establishment of rational modes of melt overheating, leading to a significant change in the dispersion and morphology of structural components. In particular, with an increase in the melt overheating temperature to 900 °C with holding and subsequent rapid cooling to the casting temperature, a decrease in the average size of dendritic cells of the aluminum solid solution from 39 μm to 13 μm was observed. We also noticed the refinement of eutectic inclusions of the Mg2Si phase with compact morphology. An increased level of mechanical properties was noted; the maximum values of tensile strength and elongation reached 228 MPa and 5.24%, respectively, which exceeded the initial values by 22.5% and 52.3%, correspondingly. The microhardness of the aluminum solid solution sequentially increased from 38.21 to 56.5 HV with an increase in the temperature during melt overheating. According to the EDS linear scanning, an increase in the superheat temperature of the melt is accompanied by an increase in the degree of saturation of the solid solution with magnesium.