Materials In Different States Research Articles

Effects of Ti on the solidification and crystallization behavior of nanocomposite permanent material under different cooling rates

Effects of Ti on the crystallization behavior, phase composition, microstructure and magnetic properties of Nd2Fe14B/α-Fe dual-phase nanocomposite permanent magnet materials in different states were studied, respectively. The results show that Ti could affect the solidification and crystallization behavior of dual-phase nanocomposite materials by regulating the cooling rate during the rapid solidification process. When the cooling rate is slow, part of Ti atoms enters the soft magnetic phase α-Fe, and part forms the TiFe2 phase around the hard magnetic phase. Exchange coupling is enhanced. The maximum energy product and the remanence of the alloy are 10.54 MGOe and 8.34 kGs, respectively. When the cooling rate faster, Ti can stabilize another ferromagnetic ThMn12-type phase with a low coercivity and maximum energy product, which should be avoided. When the cooling rate is fast enough to form amorphous, Ti and Fe preferentially combine to form the TiFe2 phase during crystallization, which selectively inhibits the growth of the hard magnetic phase and the precipitation of the soft magnetic phase, resulting in a significant enhancement of coercivity to 12.82 kOe. By regulating the mechanism of Ti in the solidification and crystallization process, nanocomposite permanent magnet materials with varying magnetic characteristics can be obtained, offering a flexible approach to tailoring their performance according to specific application requirements.

Dynamics, uncertainty and control in circular supply chains

This work introduces a prototype dynamic model of a circular supply chain based on the state-task network paradigm, and a framework for characterizing the effect of uncertainty on the system dynamics. Processing tasks are represented using transfer functions coupled with saturation functions to capture physical limitations such as inventory depletion. Physically-motivated uncertain parameters are used in the aforementioned transfer functions. Closed-form expressions are derived for the mean and variance of inventories of material in different states, showing that the variance of inventory increases over time. The results are validated via extensive simulations, complemented by an example implementation of model predictive control for tracking material inventory targets and reducing variance.

Probing atomic structure of beam-sensitive energy materials in their native states using cryogenic transmission electron microscopes

SummaryOrganic–inorganic hybrid perovskite nanoplatelets (NPLs) have emerged as promising materials for solar energy. However, the structural instability under electron beam hinders further probing and understanding of its crystalline structures and defects at the atomic scale. Taking methylammonium bromide perovskite methylammonium lead bromide (CH3NH3PbBr3 (MAPbBr3)) perovskite NPLs as model material, we performed atomic-scale characterization of the native state of the hybrid perovskite solar cell material in different states using ultra-low-dose cryo-TEM imaging. With a series of observation at different growth time, we revealed the growth pattern of such MAPbBr3 material from an initially stacked slices with rotational moiré fringes to a perfect single-crystalline structure of NPLs. Our high-resolution cryo-TEM further enabled the atomic-scale investigations of solid electrolyte interphase (SEI) and sodium (Na) dendrite materials, which can largely impact the safety and life of batteries. This study offers insights on the atomic scale characterization of a wide variety of beam-sensitive materials, inspiring us to probe more materials with cryo-transmission electron microscopes (TEM).

Using nested mappings for heat capacity data processing

In the article discrete approach based on self-similar hierarchical system of recurrent equations is proposed. The basic element of this system is linear stationary recurrent equation with constant coefficients. In general, such system has an endless nested structure, limited by the level, where its coefficients become constants.For processing heat capacity data, the proposed system was reduced to equation with uniformly varying coefficients, which is able to successfully describe a wide range of dependencies and make reliable predictions. The flexibility and convenience of this approach were shown by the example of various descriptions of heat capacity data of materials in different states and temperature ranges.

Eucommia ulmoides gum-based engineering materials: fascinating platforms for advanced applications

Eucommia ulmoides gum (EUG) exhibits good rubber–plastic duality and great application potential in biomedicine, textiles, aerospace, and other fields. The extraction methods of EUG include mechanical (high-temperature cooking), alkali extraction, solvent, microbial (enzymatic hydrolysis), and comprehensive methods. However, the complicated preparation process and high cost of EUG greatly limit its application. EUG is composed mainly of trans-isoprene, and the high crystallinity of EUG at room temperature showing rigid plastics is due to the relatively regular and short identity period of its molecular chain. Through regulating the ratio of the three-phase structure of EUG (regular crystal region, completely irregular amorphous region, and intermediate region of transition pattern between the crystallized and amorphous regions), it exhibits rubber elasticity at room temperature. The application of EUG is closely related to its crystallinity and cross-linking degree. The double-bond modification of EUG by physical or chemical method can regulate its crystalline structure and cross-linking structure, so that EUG engineering materials that meet the performance requirements of multiple fields can be obtained. EUG with zero cross-linking degree is linear thermoplastic material, which is usually used in artificial limb, medical composite scaffold, composites denture soft lining, and modified plastic. EUG with low cross-linking degree is thermoelastic material, which is frequently used in the preparation of shape memory material, interfacial compatibilizer, and composite film. EUG with critical cross-linking degree is rubber-type material, which is regularly used in elastomer, self-healing material, and modified rubber. In this article, the extraction technology of EUG and its pros and cons and the structure and properties of EUG and their corresponding material states in the past 10 years were systematically discussed. The research progress of engineering materials in different states was introduced, and the effect of modification on the structure and properties of EUG was discussed. The future development direction of the materials was prospected.

Analysis of Data on Zero and Negative Thermal Expansion Coefficients of Materials

Many specific features and anomalies of the properties of water at low temperatures and negative pressures or hydrogen and nitrogen at megabar pressures and high temperatures are related to zero and negative coefficients of thermal expansion. A review of numerous examples of manifestation of these features for various materials in different states is presented. A set of data and methods for the analysis of negative thermal expansion coefficients is singled out for an independent line of research.

Investigation of the Tensile Fracture Behavior of Notched C/SiC Composite Using <i>In Situ</i> SEM and Micro-CT

In order to better understand the failure mechanism of C/SiC composites, the tensile behavior of notched C/SiC composites was investigated by the in-situ scanning electron microscopy (SEM) and the micro-CT technique. Surface morphologies of the C/SiC sample during tensile loading were in-situ observed by SEM, while the three-dimensional microscopic images of the C/SiC sample before loading and after failure were obtained by micro-CT. The results showed that no cracks formed in the initial elastic stage corresponding to the linear part of the load-displacement curve. However, corresponding to the following non-linear part of the load-displacement curve, matrix crack initiation, fiber pull-out, crack propagation and deflection appeared consecutively in the notched region of the sample. What’s more, different crack growth paths existed in different directions of the sample during tensile failure. In general, approximately flat fracture formed in the plying direction and serrated or stepped fracture were observed in the needling direction. It indicated that the in-situ observation method combining SEM and micro-CT can obtain the micro-structure images of the material in different states, which is helpful to analyze the fracture failure mechanism of composites.

INFLUENCE OF DIFFERENT STATE PARAMETERS ON THE BEHAVIOR OF FATIGUE CURVES

The behavior of materials in different areas of cyclic loading is very different and can depend on both their state and the test conditions. As the criteria for damage during cyclic loading, width of the hysteresis loop, parameters of the dislocation theory, magnitude of the stresses and their intensity, relation with the grain size, etc. can serve. Meanwhile, there is still no general complex mathematical equation reflecting the effect on metal damage during fatigue of such important characteristics of polycrystals as the density or defectiveness, the stress relaxation rate, loading rate, structural and energy state of the material, namely, strength and hardness, and the applied emerging stress-strain state. In the present work, the influence of cyclic loading on failure from the point of view of competition of the loading and relaxation rates of internal stresses with allowance for the spectrum of plastic deformation waves is considered. Depending on the type and loading conditions, a different spectrum of the waves of plastic deformation and fracture is formed under different kinds and loading conditions. It is shown that as the frequency of cyclic loading (strain rate) increases, the voltage rise time decreases, and the voltage corresponding to a certain plastic deformation increases. The intensity of reducing the resistance to material destruction is related to the intensity of damage accumulation. General analytical equations for describing the behavior of the fatigue curves of polycrystalline metals and alloys are obtained, which allow one to represent the influence of the factors of their state in dependence on the influence of the external conditions of cyclic loading. The equation allows to simulate various situations of behavior of polycrystals with fatigue in metals, as well as to analyze the fatigue curves of materials in different states. Since the relaxation rate in polycrystals is the vectorial value = pl.d + p , representing the sum of the vectors of the plastic deformation rate ( pl.d ) and the actual fracture rate p is the nucleation and growth of cracks, then taking this into account, with increasing pl.d with constant total relaxation rate, the rate of destruction will decrease, the fatigue curve will go lower (position). Fatigue curves are constructed for various parameters of the structuralenergy state (Brinell hardness) and density-dependent coefficients.

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

Synchrotron radiation is the most versatile way to explore biological materials in different states: monocrystalline, polycrystalline, solution, colloids and multiscale architectures. Steady improvements in instrumentation have made synchrotrons the most flexible intense X-ray source. The wide range of applications of synchrotron radiation is commensurate with the structural diversity and complexity of the molecules and macromolecules that form the collection of substrates investigated by glycoscience. The present review illustrates how synchrotron-based experiments have contributed to our understanding in the field of structural glycobiology. Structural characterization of protein–carbohydrate interactions of the families of most glycan-interacting proteins (including glycosyl transferases and hydrolases, lectins, antibodies and GAG-binding proteins) are presented. Examples concerned with glycolipids and colloids are also covered as well as some dealing with the structures and multiscale architectures of polysaccharides. Insights into the kinetics of catalytic events observed in the crystalline state are also presented as well as some aspects of structure determination of protein in solution.

Optimized Temperature Effect of Li-Ion Diffusion with Layer Distance in Li(NixMnyCoz)O2 cathode Materials for High Performance Li-Ion Battery

Understanding and optimizing temperature effects of Li-ion diffusion by analyzing crystal structures of layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) materials are important to develop advanced rechargeable Li-ion batteries (LIBs) for multi-temperature applications with high power density. Combined with experiments and ab initio calculations, the layer distances and kinetics of Li-ion diffusion of NMC materials in different states of Li-ion de-intercalation and temperatures are investigated systematically. An improved model is also developed to reduce the system error of “Galvanostatic Intermittent Titration Technique” (GITT) with a correction of NMC particle size distribution. The Li-ion diffusion coefficients of all the NMC materials are measured from -25 to 50 °C. It is found that the Li-ion diffusion coefficient of LiNi0.6Mn0.2Co0.2O2 is the largest with the minimum temperature effect. Ab initio calculations and XRD measurements indicate that the larger Li slab space is benefited to Li-ion diffusion with minimum temperature effect in layered NMC materials. Figure 1

Piecewise Multiple Linear Models for Pavement Marking Retroreflectivity Prediction Under Effect of Winter Weather Events

Most existing models for prediction of pavement marking retroreflectivity have been developed from data collected in locations with similar weather conditions; therefore, the effect of different weather conditions, such as winter weather events, has not been extensively studied. This study develops degradation models that can predict retroreflectivity of durable pavement marking materials under various winter weather conditions. Piecewise multiple linear models are proposed to explicitly account for the effect of winter weather events in this study. In comparisons of the proposed models with conventional multiple linear models (MLMs) developed from the same set of data, the proposed models outperformed the MLMs, and the overall root-mean-square error improved from 204.6 mcd/m2/lux for MLMs to 106.5 mcd/m2/lux for piecewise MLMs. The proposed models also show robust and consistent results in predicting retroreflectivity of different materials in different states. The results indicate that the proposed method can be adopted by various states and regions for comprehensive retroreflectivity prediction under various weather conditions.

Optimized Temperature Effect of Li‐Ion Diffusion with Layer Distance in Li(NixMnyCoz)O2 Cathode Materials for High Performance Li‐Ion Battery

Understanding and optimizing the temperature effects of Li‐ion diffusion by analyzing crystal structures of layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) materials is important to develop advanced rechargeable Li‐ion batteries (LIBs) for multi‐temperature applications with high power density. Combined with experiments and ab initio calculations, the layer distances and kinetics of Li‐ion diffusion of LiNixMnyCozO2 (NMC) materials in different states of Li‐ion de‐intercalation and temperatures are investigated systematically. An improved model is also developed to reduce the system error of the “Galvanostatic Intermittent Titration Technique” with a correction of NMC particle size distribution. The Li‐ion diffusion coefficients of all the NMC materials are measured from −25 to 50 °C. It is found that the Li‐ion diffusion coefficient of LiNi0.6Mn0.2Co0.2O2 is the largest with the minimum temperature effect. Ab initio calculations and XRD measurements indicate that the larger Li slab space benefits to Li‐ion diffusion with minimum temperature effect in layered NMC materials.

Recrystallization behaviour of AA6063 extrusions

Cylindrical profiles of an AA6063 aluminium alloy were produced in a lab-scale direct extrusion set-up. The extrusion was performed at 300 °C, 450 °C and 550 °C, respectively, with the same ram speed. Immediate water quenching was applied to the profiles and the end of billet (butt-end) after extrusion. Microstructure and texture of the material in different states were measured by electron back-scattered diffraction. Only the profile extruded at 300 °C, was found in the deformed state after extrusion, featuring a fibrous grain structure and a strong <111> and weak <100> double fibre texture. Post-extrusion annealing of this profile at 450 °C resulted in an almost fully recrystallized structure (recrystallized fraction of 87%) and with a texture similar to that of the as-deformed state. The profile extruded at 450 °C was almost fully recrystallized (recrystallization fraction 91%) already after quenching, and with a texture characterized by a weak <111> and strong <100> double fibre. The profile extruded at 550 °C showed a partially recrystallized grain structure with recrystallization fraction of 71%, and with a texture dominated by a <100> fibre. The influence of the deformation conditions on the recrystallization behaviour, in terms of recrystallization kinetics and mechanisms, are discussed in view of these results.

Effect of Neutron Irradiation on Brittle Fracture Initiation in VVER-1000 Reactor Pressure Vessel Materials

Abstract This work contains fractographic analysis of base metal and weld metal specimens of a VVER-1000 reactor pressure vessel (RPV) in initial state and after neutron irradiation. In this work, two main types of brittle fracture origins were discovered for VVER-1000 RPV materials in different states—non-metallic inclusions and grain or subgrain boundaries, as well as the correlation between the cleavage initiation distance and critical stress-intensity factor KJc values for each type of fracture origin. In this paper, evolution of relative proportion between these two types of origins under neutron irradiation was also studied.

Coordinate Measurements of Geometrically Complex Ceramic Parts

The article presents the results of numerical and experimental investigations concerning contact coordinate measurements of complex ceramic parts made of Al2O3 and ZrO2 based ceramic materials in different states. The investigated parts were manufactured by using two machining processes: ultrasonic assisted grinding and conventional grinding. The results of investigations may be used in order to improve the manufacturing process of geometrically complex ceramic parts.

A visco-hyperelastic constitutive model for rubber-like materials: A rate-dependent relaxation time scheme

A three-dimensional visco-hyperelastic constitutive model is developed to describe the rate-dependent behavior of rubber-like materials at large deformations. The model encompasses a hyperelastic part which uses the “Exp–Ln” strain energy function to characterize the equilibrium response and a viscous part capturing the rate sensitivity using a hereditary integral form which links the overstress to the history of stored strain energy. A physically consistent rate-dependent relaxation time scheme is introduced which reduces the number of required material parameters and also facilitates the calibration process. The proposed model is verified using various uniaxial experimental data in different rate ranges. Furthermore, the model is incorporated via VUMAT in ABAQUS/Explicit to examine its performance in three-dimensional deformations. To this end, finite element analysis of an elastomeric bushing is performed and the results are compared to those of experiment. It is then concluded that, the proposed constitutive relations are quite efficient in predicting the behavior of rubber-like materials in different states of deformation and also in wide ranges of strain rate.

Formation and structure of vortex zones arising upon explosion welding of carbon steels

Presented are the results of investigation of vortex zones arising upon explosion welding of thin plates of steel 20. Specific features of the structure of the vortices and zones of the deformed material adjacent to them have been revealed by methods of structure analysis. It has been shown that in the process of explosive loading the central regions of the vortices characterized by an enhanced carbon content were in the molten state. The microhardness in the region of vortex zones reaches 5700 MPa. The character of the arrangement of ferrite grains and martensite microvolumes in peripheral regions of vortices is caused by intense rotation of the material. The intense intermixing of materials in different states of aggregation in vortex zones is one of the factors responsible for the formation of cavities, whose volume exceeds the volume shrinkage occurring upon casting of carbon steels. It has been established that traces of vortex zones are retained even after one-hour annealing of welded packets at 800°C.

Modeling of Strength Degradation for Fiber-reinforced Polymer Composites in Fire

A model for predicting composite material strength degradation under elevated and high temperatures is proposed. This model is based on the morphology of the mixture of materials in different states. The degradation of resin-dominated shear strength can be well described by the rule of mixture while the degradation of nominal compressive strength tends to follow the lower bound of strength defined by the inverse rule of mixture. Composite materials under tension may exhibit fiber- or resin-dominated behavior. In a lower temperature range, strength is dominated by the fiber tensile strength, while at higher temperatures, tensile components may exhibit resin-dominated failure in joint regions. The parameters required in the model can be obtained on the basis of kinetic analysis of dynamic mechanical analysis results. The fitting of experimental curves of material strength degradation is not necessary. The proposed modeling scheme can easily be incorporated into structural theory to predict mechanical responses and time-to-failure.

Numerical simulation of hot hydrostatic extrusion of W-40 wt.% Cu

The relationship of stress vs. strain of W-40 wt.% Cu at different temperatures and strain rates is obtained by the true stress–strain data obtained from tests using a Gleeble1500 thermo-simulator. The friction factors without and with lubricant of oil and graphite are determined by ring upset experiments. The heat transfer of the billet in various conditions is simulated by DEFORM-2D, and the results are compared with the temperature–time data obtained from heat transfer tests to confirm the convection coefficient and the heat transfer coefficient between the billet and other materials in different states. Based on these works, the hot hydrostatic extrusion process of W-40 wt.% Cu is simulated. The results show that the calculated deformation loads during extrusion at different temperatures are in good agreement with the experimental results. The variation of the deformation load during hot hydrostatic extrusion process has been studied, and the distribution of temperature field, equivalent stress, equivalent strain and relative density of the billet are obtained.

Influence of Cr additions on corrosion resistance of Fe- and Co-based metallic glasses and nanocrystals in H2SO4

The influence of Cr concentration on the corrosion resistance of Fe73.5Si13.5B9Nb3Cu1 and Co73.5Si13.5B9Nb3Cu1 metallic glasses was studied by DC electrochemical methods in different concentrations of H2SO4 (1, 3 and 5M) at room temperature. Gravimetric tests were performed to establish the reliability of the data obtained electrochemically. Every test was determined with the same material in different states: amorphous, nanocrystalline and crystalline. In all cases metallic glasses and nanocrystals showed better resistance to corrosion in the tested conditions with increasing chromium concentration. However, in test conditions, the Fe-based materials maintained a high corrosion rate. The corrosion resistance of Co-based materials was slightly greater than that of Fe-based materials.