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Level-cut Gaussian/filtered Poisson, mosaic, and Voronoi tessellation random fields are used to model two-phase random materials. Essential properties of these random fields are reviewed and Monte Carlo algorithms for generating synthetic two-phase materials are presented. Numerical examples are used to illustrate the implementation and features of these models for two-phase materials.

It is discussed that the classical effective medium theory for the elastic properties of random heterogeneous materials is not congruous with the effective medium theory for the electrical conductivity. In particular, when describing the elastic and electro-conductive properties of a strongly inhomogeneous two-phase composite material, the steep rise of effective parameters occurs at different concentrations. To achieve the logical concordance between the cross-property relations, a modification of the effective medium theory of the elastic properties is introduced. It is shown that the qualitative conclusions of the theory do not change, while a possibility of describing a broader class of composite materials with various percolation thresholds arises. It is determined under what conditions there is an elasticity theory analogue of the Dykhne formula for the effective conductivity. The theoretical results are supported by known experiments and show improvement over the existing approach. The introduction of the theory with the variable percolation threshold paves the way for describing the magnetorheological properties of magnetoactive elastomers. A similar approach has been recently used for the description of magneto-dielectric and magnetic properties.

La/Pr co-doped ceria (LCP) is processed to fabricate low-temperature ceramic fuel cell based on industrial-grade rare-earth carbonate electrolyte that is reached above a maximum power density of 750 mW/cm 2 at 520 °C. The charge carriers are investigated through LCP fuel cell having symmetric NCAL (Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ ) electrodes using proton conductor BCZY (BaCe 0.7 Zr 0.1 Y 0.2 O 3-δ ) as a blocking layer and are found protons that dominate during the cell operation. The results of associated characterizations for HCC (hydrogen concentration cell) and the OCC (oxygen concentration cell) reveal that LCP material is mixed conductor of both protons and oxygen ions simultaneously. Transmission electron microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis before and after the electrochemical testing of the cell are performed which show an amorphous layer of LiOH/Li 2 CO 3 mixture that is formed after the tests on the surface of LCP structure. Conceptually, it looks that LiOH/Li 2 CO 3 mixture in molten state in the interface region of two-phase material promotes the proton conduction through LCP electrolyte, with negligible oxygen ion conduction.

This paper presents generalized results of numerical analysis of the effect of mesoscopic heat dissipation and heat transfer on the temperature field formed in a shock-compressed viscoplastic porous material containing spherical pores with a thin layer of plasticizer on the pore surface in plastic flow. The results of the study are used to obtain a theoretical estimate of the effect of the mechanical properties of the phases on the critical conditions for shock-wave initiation of chemical reaction in the two-phase porous energetic material.

In phase-change memory devices, a material is cycled between glassy and crystalline states. The highly temperature-dependent kinetics of its crystallization process enables application in memory technology, but the transition has not been resolved on an atomic scale. Using femtosecond x-ray diffraction and ab initio computer simulations, we determined the time-dependent pair-correlation function of phase-change materials throughout the melt-quenching and crystallization process.We found a liquid–liquid phase transition in the phase-change materials Ag₄In₃Sb67Te26 and Ge15Sb85 at 660 and 610 kelvin, respectively. The transition is predominantly caused by the onset of Peierls distortions, the amplitude of which correlates with an increase of the apparent activation energy of diffusivity. This reveals a relationship between atomic structure and kinetics, enabling a systematic optimization of the memory-switching kinetics.

Extended Preisach model parameters can be strongly related to microstructural properties of material. It can also include real physical magnetization mechanisms such as domain wall motion and domain rotation. This paper shows that Preisach model is able to anticipate different phases in material structure. Existence of different phases in the material are due to thermal treatment, which is used to improve magnetic properties of amorphous alloys. Model was verified using ring shaped cores made of bilayered amorphous ribbons, which served as a physical model of the loosely coupled two phase ferromagnetic material with distinct magnetic properties.

Two-phase materials are commonly used in engineering application because of its various properties like strength, thermal conductivity, durability and toughness etc. Effective thermal conductivity (ETC) of two-phase material is the fundamental property to predict its thermal performance. Various geometry (spheres, cylinders, irregular particles) have been considered by researchers for calculating ETC of two-phase materials. Due to complex structure, hollow circular cylinder geometry is not reported yet. In this paper, two-dimensional periodic two-phase system, with hollow circular cylinder shape is considered for calculating ETC. In present work unit cell approach method is used to derive collocated parameters model for estimation of ETC. Hollow circular cylinder model with Ψ = 0.2 gives good result for estimating ETC with average percentage error of 6.46%.

Geopolymers are synthesized using anthropogenic raw materials and waste from the energy industry. Their preparation necessitates an alkaline activator, which facilitates the dissolution of raw materials and their subsequent binding. At present, geopolymers are considered a promising material with the potential to replace conventional cement-based products. This research investigates foamed geopolymer materials based on fly ash, natural fibers, and phase-change materials. The study utilized three distinct types of fibers and two phase-change materials manufactured by Rubitherm Technologies GmbH of Germany. This paper presents the results of the thermal conductivity coefficient and specific heat tests on the finished foams. Additionally, compressive strength tests were conducted on the samples after 28 days. Natural fibers decreased the insulation parameter by 12%, while PCM enhanced it by up to 6%. The addition of fibers increased the compressive strength by nearly 30%, whereas PCM reduced this by as little as 14%. Natural fibers and phase-change materials had an increased heat capacity by up to 35%. The results demonstrated the material’s potential in various industrial sectors, with the primary areas of application being building materials and insulations. The findings illustrate the significant potential of these composites as energetically and environmentally sustainable materials.

The mechanisms of superplasticity occurring in conventional materials, having grains sizes of the order of a few microns, are now understood reasonably well. However, very recent advances in the processing of ultrafine-grained (UFG) metals have provided an opportunity to extend the understanding of flow behavior to include UFG materials with submicrometer grain sizes. In practice, processing through the application of severe plastic deformation (SPD), as in equal-channel angular pressing (ECAP) and high-pressure torsion (HPT), has permitted the fabrication of relatively large samples having UFG microstructures. Since the occurrence of superplastic flow generally requires a grain size smaller than ~10 μm, it is reasonable to anticipate that materials processed by SPD will exhibit superplastic ductilities when pulled in tension at elevated temperatures. This review examines recent results that demonstrate the occurrence of exceptional superplastic flow in a series of UFG aluminum and magnesium alloys after ECAP and HPT. The results are analyzed to evaluate the superplastic flow mechanism and to compare with materials processed using different techniques. The critical issue of microstructural inhomogeneity is examined in two-phase UFG materials after SPD processing and the influence of microstructural homogeneity on the superplastic properties is also demonstrated.

With the development of finite element theory and computer technology, the application of numerical simulation methods to disclose the physical mechanisms of deformation and damage within the internal structure of concrete materials is of great significance for the study of static and dynamic mechanical properties at the microscopic level. This paper provides a comprehensive overview of the current research status concerning the numerical simulation of fine-scale mechanics in concrete. The emphasis is on the research advancements in fine-structure modeling of concrete and two-phase materials within the transition zone between aggregates and interfaces, particularly in relation to concrete deformation, damage, and the occurrence of fracture damage. Furthermore, an account is given of the research frontiers in fine-scale numerical simulation of concrete, encompassing domains such as fine-structure modeling of concrete, damage mechanisms, size effect, and so forth. The research findings demonstrate that, through numerical simulation by taking into account the multiphase nature and non-uniformity of concrete materials at the microscopic level, the influence of aggregates and interface transition zones on the macroscopic performance of concrete can be effectively analyzed. The employment of microscopic mechanical models for concrete is conducive to enhancing the accuracy of the microscopic mechanical analysis of concrete. The combination of X-ray computed tomography (X-CT) and finite element numerical simulation yields predictions that exhibit high consistency with experimental measurements, manifesting greater accuracy and a closer approximation to real-world conditions in contrast to traditional models. In conclusion, the article highlights the unresolved issues and prospective directions for further research in the microscopic concrete finite element simulation.