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Electron–phonon coupling plays a central role in the transport properties and photophysics of organic crystals. Successful models describing charge- and energy-transport in these systems routinely include these effects. Most models for describing photophysics, on the other hand, only incorporate local electron–phonon coupling to intramolecular vibrational modes, while nonlocal electron–phonon coupling is neglected. One might expect nonlocal coupling to have an important effect on the photophysics of organic crystals because it gives rise to large fluctuation in the charge-transfer couplings, and charge-transfer couplings play an important role in the spectroscopy of many organic crystals. Here, we study the effects of nonlocal coupling on the absorption spectrum of crystalline pentacene and 7,8,15,16-tetraazaterrylene. To this end, we develop a new mixed quantum–classical approach for including nonlocal coupling into spectroscopic and transport models for organic crystals. Importantly, our approach does not assume that the nonlocal coupling is linear, in contrast to most modern charge-transport models. We find that the nonlocal coupling broadens the absorption spectrum non-uniformly across the absorption line shape. In pentacene, for example, our model predicts that the lower Davydov component broadens considerably more than the upper Davydov component, explaining the origin of this experimental observation for the first time. By studying a simple dimer model, we are able to attribute this selective broadening to correlations between the fluctuations of the charge-transfer couplings. Overall, our method incorporates nonlocal electron–phonon coupling into spectroscopic and transport models with computational efficiency, generalizability to a wide range of organic crystals, and without any assumption of linearity. [ABSTRACT FROM AUTHOR]

The whole optical phonon spectrum of quasiconfined (CO), propagating (PR), and interface (IF) modes in wurtzite III-nitride cylindrical core-multishell nanowires (CMSNWs) is obtained based on the dielectric continuum and Loudon's uniaxial crystal models considering the ternary mixed crystal effect. A transfer matrix method calculation shows that there are six types of CO modes and one type of PR mode in a three-layered CMSNW. For any fixed component, only permitted types of CO modes exist in allowable frequency regions, while the PR modes appear only when components are almost the same in all layers, originating from anisotropic optical phonons in bulk wurtzite nitride. The whole spectrum reveals two mode transformations: one is between PR and IF modes by adjusting components in different layers; the other is continuous among five possible modes at any fixed component with connected frequency regions. The dispersion relations and corresponding electrostatic potentials of the whole optical phonon spectrum are helpful to understand the frequency-dependent electron–phonon interaction in the future. The analysis process can be extended to arbitrary nitride cylindrical CMSNWs for the modulation of optical phonon related properties. [ABSTRACT FROM AUTHOR]

Lattice constant mismatch between materials affects the quality of thin film fabrication. For this reason, lattice constants information is vital in the design of materials for technological applications. The determination of lattice constants via experimental analysis is relatively expensive and laborious. As a result, several linear empirical models have been proposed to predict the lattice constant of crystal structures. However, the accuracies of these models are limited partly due to their failure to account for nonlinearity in the atomic parameters-lattice constant relationship. Machine learning techniques have shown excellent ability to deal with nonlinear problems in many areas of materials science; hence, they are considered suitable computation tools to study the crystal structure of materials. In this contribution, we developed a support vector regression (SVR) model to predict the lattice constant of cubic crystals of the form A2XY6 (A = K, Cs, Rb, TI; X = tetravalent cation; and Y = F, Cl, Br, I). The SVR algorithm uses the ionic radii and electronegativities data of the constituent elements of A2XY6 cubic crystals as model inputs. The robustness of the proposed model was demonstrated by comparing our result with an existing linear model based on 26 cubic crystal samples. The result revealed a total relative deviation of 1.757 and 2.704 for the SVR model and the existing linear equation, respectively. This result proves that the SVR model has a huge potential in the search for new materials for different applications. [ABSTRACT FROM AUTHOR]

We have extended the multiconfigurational Ehrenfest (MCE) approach to investigate the dynamics of a one-dimensional Holstein molecular crystal model. It has been shown that the extended MCE approach yields results in perfect agreement with benchmark calculations by the hierarchy equations of motion method. The accuracies of the MCE approach in describing the dynamical properties of the Holstein polaron over a wide range of exciton transfer integrals and exciton-phonon couplings are carefully examined by a detailed comparison with the fully variational multiple Davydov D2 ansatz. It is found that while the MCE approach and the multi-D2 ansatz produce almost exactly the same results for a small transfer integral, the results obtained by the multi-D2 ansatz start to deviate from those by the MCE approach at longer times for a large transfer integral. A large number of coherent state basis functions are required to characterize the delocalized features of the phonon wavefunction in the case of large transfer integral, which becomes computationally too demanding for the multi-D2 ansatz. The MCE approach, on the other hand, uses hundreds to thousands of trajectory guided basis functions and converges very well, thus providing an effective tool for accurate and efficient simulations of polaron dynamics. [ABSTRACT FROM AUTHOR]

As a new type of two-dimensional material, black phosphorus (BP) has great potential for development. However, the unclear synthesis mechanism means that its practical application is challenging. In this study, after BP synthesis (without a process intervention such as an interrupted reaction), the material transformation mechanism was studied by studying the product state under various process factors. Based on the Schäfer chemical vapor transport equations, the BP crystal growth model was deduced. In the five temperature stages of BP growth, the existing form and state, position and function, as well as the formation and transformation mechanism of each substance are described in detail. The key temperature stages of the formation and transformation of the nucleating agent and its precursors were determined to be stage III and stage IV. The influence and mechanism of temperature distribution and pressure in a muffle furnace on BP synthesis were ascertained, which provided a basis for controllable and efficient synthesis of BP. [ABSTRACT FROM AUTHOR]

The deformation-induced surface roughening of an Al-Mg alloy is analyzed using a combination of experiments and modeling. A mesoscale oligocrystal of AA5052-O, obtained by recrystallization annealing and subsequent thickness reduction by machining, that contains approx. 40 grains is subjected to uniaxial tension. The specimen contains one layer of grains through the thickness. A laser confocal microscope is used to measure the surface topography of the deformed specimen. A finite element model with realistic (non-columnar) shapes of the grains based on a pair of Electron Back-Scatter Diffraction (EBSD) scans of a given specimen is constructed using a custom-developed shape interpolation procedure. A Crystal Plasticity Finite Element (CPFE) framework is then applied to the voxel model of the tension test of the oligocrystal. The unknown material parameters are determined inversely using an efficient, custom-built optimizer. Predictions of the deformed shape of the specimen, surface topography, evolution of the average roughness with straining and texture evolution are compared to experiments. The model reproduces the averaged features of the problem, while missing some local details. As an additional verification of the CPFE model, the statistics of surface roughening are analyzed by simulating uniaxial tension of an AA5052-O polycrystal and comparing it to experiments. The averaged predictions are found to be in good agreement with the experimentally observed trends. Finally, using the same polycrystalline specimen, texture–morphology relations are discovered, using a symbolic Monte Carlo approach. Simple relations between the Schmid factor and roughness can be inferred purely from the experiments. Novelties of this work include: realistic 3D shapes of the grains; efficient and accurate identification of material parameters instead of manual tuning; a fully analytical Jacobian for the crystal plasticity model with quadratic convergence; novel texture–morphology relations for polycrystal. [ABSTRACT FROM AUTHOR]

Self-assembly of 3D interiors and iridescence properties of poly(β-hydroxybutyric acid-co-β-hydroxyvaleric acid) (PHBV) periodic crystals are examined using microcopy techniques and microbeam X-ray diffraction. Morphology of PHBV can be tailored by crystallizing in presence of poly(vinyl acetate) (PVAc) or poly(trimethylene adipate) (PTA) for displaying desired periodicity patterns. The regular alternate-layered lamellae of banded PHBV crystal aggregates, resembling the structures the natural mineral moonstone or nacre, are examined to elaborate the origin of light interference and formation mechanisms of periodic lamellar aggregation of PHBV spherulites. By using PHBV as a convenient model and the crystal diffraction data, this continuing work demonstrates unique methodology for effectively studying the periodic assembly in widely varying polymers with similar aggregates. Grating structures in periodically assembled polymer crystals can be tailored for microstructure with orderly periodicity. [ABSTRACT FROM AUTHOR]

High-throughput virtual screening for crystals aims to discover new materials by evaluating the property of every virtual candidate in the database exhaustively. During this process, the major computational bottleneck is the costly structural relaxation of each hypothetical material on the large-scale dataset using density functional theory (DFT) calculations. Here, we present a generative domain translation framework that maps the unrelaxed structural domains to the relaxed domains, enabling data-driven structural translations. The model predicts the materials formation energy with a small mean absolute error without DFT relaxations, and furthermore can produce the atomic coordinates consistent with the DFT relaxed structures. The utility of the proposed concept is not restricted to the structural domains, and we expect that it can be extended to translate the domain of easy-to-compute properties into the domain of more difficult properties. [ABSTRACT FROM AUTHOR]

In situ attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR‐SEIRAS) is often used to investigate the near‐surface electrocatalytic reaction environment. However, there is a gap in directly correlating the near‐surface reaction environment with electrocatalytic reaction rates. To that end, we designed an electrochemical flow reactor for operando electrochemical ATR‐SEIRAS and demonstrate its capability with the CO2 reduction reaction (CO2RR). Roughened gold catalyst thin films are prepared on ATR silicon crystals as a model system to probe local species under CO2RR conditions in 0.1 M KHCO3. We measured changes in the interfacial CO2 concentration as a function of applied potential and electrolyte flow rate in operando, allowing us to correlate the changes in reaction rates with the observed CO2 concentration. Including the choice of the catalyst and electrolyte, coupling hydrodynamic control with ATR‐SEIRAS in this platform enables investigations of how the local microenvironment affects the activity and selectivity of electrochemical reactions. [ABSTRACT FROM AUTHOR]

Crystal structures of high-temperature t- (LaF3-type) and low-temperature β- (β-YF3-type) modifications of 61(58Ce0.564Gd0.5)F3 – "pseudo61PmF3" near the temperature of a polymorphic transformation (PolTr) (−148 ± 5 °C) were studied by in situ X-ray diffraction (XRD). During the t- → β- "pseudo61PmF3" PolTr (at cooling) anions are ordered in the direction perpendicular to the hexagonal close packing (HCP) layers. This is accompanied by 13% stretching of the t-type crystal lattice in the <010> direction and compression in the <100> (0.8%) and <001> (0.9%) directions. The structural changes in t- and β- "pseudo61PmF3" at heating from −148 to +20 °C represent changes (decrease and increase) in cation–anion bond lengths (BL) without changing the shape of the coordination polyhedron (CP). "Pseudo61PmF3" is a material with giant negative thermal expansion at PolTr (NTE-II). The decrease in volume during the β- → t- "pseudo61PmF3" PolTr (at heating) is 3.8%. [ABSTRACT FROM AUTHOR]

We shall investigate the existence, uniqueness and regularity of global solutions to a Cauchy problem for a square phase crystal field model with applications to crystal dynamics. To prove the existence of weak solutions we employ the energy method, and to investigate the regularity of solutions we make use of various techniques to derive delicate a priori estimates. [ABSTRACT FROM AUTHOR]

In this article, we prove the global existence of weak solutions to an initial boundary value problem with an exponential and p-Laplacian nonlinearity. The equation is a continuum limit of a family of kinetic Monte Carlo models of crystal surface relaxation. In our investigation, we find a weak solution where the exponent in the equation, - Δ p u , can have a singular part in accordance with the Lebesgue decomposition theorem. The singular portion of - Δ p u corresponds to where - Δ p u = - ∞ , which leads it to have a canceling effect with the exponential nonlinearity. This effect has already been demonstrated for the case of a linear exponent p = 2 , and for the time-independent problem. Our investigation reveals that we can exploit this same effect in the time-dependent case with nonlinear exponent. We obtain a solution by first forming a sequence of approximate solutions and then passing to the limit. The key to our existence result lies in the observation that one can still obtain the precompactness of the term e - Δ p u despite a complete lack of estimates in the time direction. However, we must assume that 1 < p ≤ 2 . [ABSTRACT FROM AUTHOR]

Train vibrations can travel through the track, tunnel structure, and surrounding strata as well as into the structure of buildings near tunnels, where they can be radiated as low-frequency vibration waves and noises inside the building. Low-frequency vibration reduction is a major challenge for vibration control technology. Herein, the new phononic-like crystal metaconcrete material was invented to make the track bed for decreasing vibration induced by trains because it can open low-frequency bandgaps to reduce the low-frequency vibration in actual subway engineering. First, the original phononic-like crystal model was optimized to improve the vibration reduction effect for low-frequency bandgaps. Second, the metaconcrete track beds were conducted according to the new phononic-like crystal model based on the vibration reduction need. Finally, the metaconcrete track beds were installed in the Ning-Ju line of Nanjing Metro in Nanjing, China, and the vibration reduction effect was monitored. The monitoring results in the Ning-Ju line demonstrate that the new phononic-like crystal structure metaconcrete track bed has excellent vibration reduction performance for rail transportation. [ABSTRACT FROM AUTHOR]

This paper presents a sixth-order nonlinear parabolic problem of the square phase-field crystal model. We first demonstrate the time-discrete backward Euler scheme with mass conservation and energy stability. Then, we prove the unconditionally optimal error estimates for the time-discrete backward Euler scheme. In the end, we present 2D and 3D numerical simulations to confirm the theoretical results. [ABSTRACT FROM AUTHOR]

In this work, a constitutive model is developed by incorporating precipitation strengthening into a dislocation-density-based crystal plasticity (CP) model to simulate the mechanical properties of 2024 aluminium alloy (AA). The proposed model considers the contributions of solid solution strengthening and strengthening from dislocation–precipitate interactions into the total slip resistance along with the forest hardening due to dislocation–dislocation interactions. A term accounting for the multiplication of dislocations due to their interactions with the non-shearable precipitates in the alloy is incorporated in the hardening law. The developed precipitation strengthening-based CP model is implemented into the crystal plasticity finite element method (CPFEM) for simulating the macroscopic mechanical behavior of AA2024-T3 alloy for uniaxial tension over various strain rates. The macroscopic response of the polycrystal representative volume element (RVE) used for simulations is computed using computational homogenization. The effect of meshing resolution on the RVE response is studied using four different mesh discretizations. Predictions of the macroscopic behavior by the developed model are in good agreement with the experimental findings. Additionally, the contribution of model parameters to the total uncertainty of the predicted stress has been assessed by conducting a sensitivity analysis. A parametric analysis with different precipitate radii and volume fractions has been done for finding the effect of precipitates on the macroscopic and localized deformation. [ABSTRACT FROM AUTHOR]

In the current work, a multiscale model was developed coupling a macro-model with the macromechanical physically based yield strength and a crystal plasticity model with micromechanical properties and realistic grain orientation based on the representative volume element. The simulation results show that the effect of microstructure on the macromechanical properties can be considered in the macro constitutive model due to a good consistency between experimental and computed results; whereas solid strengthening, grain boundaries, and dislocation density played a more crucial role than others. Besides coupling simulation and microstructure by EBSD, the microstructure evolution can be well explained by the micromechanical model. Strain is related to the grain orientation, leading to inhomogeneous deformation, forming the various Schmid factor and slip systems. A plastic strain occurs close to the grain boundaries and declines into the grain, resulting in higher kernel average misorientation (KAM) and geometry necessary dislocations (GNDs) in the grain boundaries. The higher the loading, the higher the local strain. Shear bands with around 45 degrees can be formed, resulting in crack initiation and tensile shear failure. This work has developed the guidance of structural integrity assessment and prediction of mechanical properties for the engineering material and components. [ABSTRACT FROM AUTHOR]

Quantitative prediction on mesoscale crystal plasticity via first principle-based methods or first principle-based multiscale methods is still unreachable, even though several approaches have arisen throughout decades for developing atomic-informed models for modeling crystalline materials from first principles. Several major difficulties have prevented to first principle-based realistic prediction of mechanical material properties. For instance, the solution of numerical models is highly affected by the loading rate and the size of the model. In this work, we aim to develop a procedure that efficiently eliminates the loading rate and the mesh size effects. This is achieved by first using machine learning (ML)-aided constitutive relations extrapolated from the first-principle-based modeling for the finite element solver, and then assessing the stress–strain relation at the mesoscale based on the homogenized strain field but utilizing the same atomistic or lattice information. As it may compromise the consistency at the finite element level, yet the calculations are based on the same atomistic potential, but performed independently. This can be interpreted as using the FE as an auxiliary tool for calculating the deformations field and achieving homogenization, while the stresses are computed from the atomic-based potential. It is shown herein that the proposed ML-based multiscale method significantly enhances the accuracy of the homogenization results comparing with other multiscale methods reported in the literature. [ABSTRACT FROM AUTHOR]

Diffraction intensities from a crystallographic experiment include contributions from the entire unit cell of the crystal: the macromolecule, the solvent around it and eventually other compounds. These contributions cannot typically be well described by an atomic model alone, i.e. using point scatterers. Indeed, entities such as disordered (bulk) solvent, semi‐ordered solvent (e.g. lipid belts in membrane proteins, ligands, ion channels) and disordered polymer loops require other types of modeling than a collection of individual atoms. This results in the model structure factors containing multiple contributions. Most macromolecular applications assume two‐component structure factors: one component arising from the atomic model and the second one describing the bulk solvent. A more accurate and detailed modeling of the disordered regions of the crystal will naturally require more than two components in the structure factors, which presents algorithmic and computational challenges. Here an efficient solution of this problem is proposed. All algorithms described in this work have been implemented in the computational crystallography toolbox (CCTBX) and are also available within Phenix software. These algorithms are rather general and do not use any assumptions about molecule type or size nor about those of its components. [ABSTRACT FROM AUTHOR]

Sequence‐register shifts remain one of the most elusive errors in experimental macromolecular models. They may affect model interpretation and propagate to newly built models from older structures. In a recent publication, it was shown that register shifts in cryo‐EM models of proteins can be detected using a systematic reassignment of short model fragments to the target sequence. Here, it is shown that the same approach can be used to detect register shifts in crystal structure models using standard, model‐bias‐corrected electron‐density maps (2mFo − DFc). Five register‐shift errors in models deposited in the PDB detected using this method are described in detail. [ABSTRACT FROM AUTHOR]

All‐small‐molecule organic solar cells (ASM‐OSCs) are challenging for their inadequate efficiency and device stability due to their more susceptive morphology. Herein, a family of isomeric small molecule donors (SMDs) is synthesized based on the benzodithiophene–terthiophene core with linear, 1st carbon, and 2nd carbon position branched butyl‐based rhodanine for ASM‐OSCs, respectively. The single crystal of thiophene‐substituted model T‐s‐Bu forms a more compact intermolecular packing with herringbone structure than slip‐layered packing‐based T‐n‐Bu and T‐i‐Bu. SM‐i‐Bu and SM‐s‐Bu show slightly blue‐shifted absorption and deepened HOMO levels in the neat film compared to SM‐n‐Bu. SM‐s‐Bu:BO‐4Cl blend films have distinct face‐on packing orientations and suitable fibrous phase separation along with more apparent microcrystals. Finally, SM‐s‐Bu:BO‐4Cl‐based device yields an improved power conversion efficiency of 16.06% compared to 15.12% and 8.22% for SM‐n‐Bu:BO‐4Cl and SM‐i‐Bu:BO‐4Cl, which is one of the top‐ranked results for BTR‐series SMDs in binary ASM‐OSCs. More importantly, the excellent storage stability with a T80 lifetime of over 1700 h and decent thermal stability is realized in SM‐s‐Bu:BO‐4Cl. This work highlights that the isomeric terminal alkyl with a branching point directly connected to the backbone for SMDs is a promising strategy for improving the crystal packing and film morphology and achieving highly efficient and stable ASM‐OSCs. [ABSTRACT FROM AUTHOR]

The modified phase field crystal (MPFC) model is a sixth-order evolutive nonlinear partial differential equation which can describe many crystal phenomena. In this paper, we propose a highly efficient and accurate numerical method to construct linear and unconditionally energy stable schemes for the MPFC model. In recent years, the scalar auxiliary variable (SAV) and SAV-based methods have attracted much attention in numerical solution for dissipative systems due to their inherent advantage of preserving certain discrete analogues of the energy dissipation law. The considered numerical schemes are based on a new SAV-type approach which named new scalar auxiliary variable (nSAV) approach. We first give a first-order energy stable numerical scheme by introducing a new SAV R(t). Then, the high-order nSAV schemes based on the k-step backward differentiation formula (BDFk) are constructed. The considered nSAV schemes allow us to construct high-order schemes for both the phase variable ϕ and ψ while only using a first-order approximation of the energy balance equation. To our knowledge, there is no careful research to give high-order accurate but energy stable schemes for the MPFC model. Meanwhile, the proposed approach only needs to solve linear equation with constant coefficients in one time step which is easy to use fast Fourier transform (FFT) to save more CPU time in calculation. Some numerical simulations are demonstrated to verify the accuracy and efficiency of our proposed schemes. [ABSTRACT FROM AUTHOR]

In this study, a new eco-friendly kaolinite–cellulose (Kaol/Cel) composite was prepared from waste red bean peels (Phaseolus vulgaris) as a source of cellulose to serve as a promising and effective adsorbent for the removal of crystal violet (CV) dye from aqueous solutions. Its characteristics were investigated through the use of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and zero-point of charge (pHpzc). The Box–Behnken design was used to improve CV adsorption on the composite by testing its primary affecting factors: loading Cel into the composite matrix of Kaol (A: 0–50%), adsorbent dosage (B: 0.02–0.05 g), pH (C: 4–10), temperature (D: 30–60 °C), and duration (E: 5–60 min). The significant interactions with the greatest CV elimination efficiency (99.86%) are as follows: BC (adsorbent dose vs. pH) and BD (adsorbent dose vs. temperature) at optimum parameters (A: 25%, B: 0.05 g, C: 10, D: 45 °C, and E: 17.5 min) for which the CV's best adsorption capacity (294.12 mg/g) was recorded. The Freundlich and pseudo-second-order kinetic models were the best isotherm and kinetic models fitting our results. Furthermore, the study investigated the mechanisms responsible for eliminating CV by utilizing Kaol/Cel–25. It detected multiple types of associations, including electrostatic, n-π, dipole–dipole, hydrogen bonding interactions, and Yoshida hydrogen bonding. These findings suggest that Kaol/Cel could be a promising starting material for developing a highly efficient adsorbent that can remove cationic dyes from aqueous environments. [ABSTRACT FROM AUTHOR]

This study aimed to propose a new approach for predicting the warm deformation behaviour of AA2060-T8 sheets by coupling computational homogenization (CH) with crystal plasticity (CP) modeling. Firstly, to reveal the warm deformation behaviour of the AA2060-T8 sheet, isothermal warm tensile testing was accomplished using a Gleeble-3800 thermomechanical simulator at the temperatures and strain rates that varied from 373 to 573 K and 0.001 to 0.1 s−1. Then, a novel crystal plasticity model was proposed for describing the grains' behaviour and reflecting the crystals' actual deformation mechanism under warm forming conditions. Afterward, to clarify the in-grain deformation and link the mechanical behaviour of AA2060-T8 with its microstructural state, RVE elements were created to represent the microstructure of AA2060-T8, where several finite elements discretized every grain. A remarkable accordance was observed between the predicted results and their experimental counterparts for all testing conditions. This signifies that coupling CH with CP modelling can successfully determine the warm deformation behaviour of AA2060-T8 (polycrystalline metals) under different working conditions. [ABSTRACT FROM AUTHOR]

1,1′-Dihydroxy-5,5′-bi-tetrazolium dihydroxylamine salt (TKX-50) is a new type of high-energy low-sense explosive with great application value, but TKX-50 made directly from the reaction has problems such as irregular crystal morphology and relatively large length-diameter, and these factors seriously affect the sensitivity of TKX-50 and limit its large-scale application. The internal defects of TKX-50 crystals have a great influence on their weakness, and studying its related properties is of great theoretical significance and application value. To further investigate the microscopic properties of TKX-50 crystals and to explore the connection between microscopic parameters and macroscopic susceptibility, this paper reports the use of molecular dynamics simulations to construct TKX-50 crystal scaling models with three types of defects—vacancy, dislocation and doping—and conducts molecular dynamics simulations. The influence of TKX-50 crystal defects on the initiation bond length, density, bonding diatomic interaction energy, and cohesive energy density of the crystal was obtained. The simulation results show that the models with a higher bond length of the initiator bond and higher percentage activated the initiator's N-N bond and lowered the bond-linked diatomic energy, cohesive energy density, and density corresponding to higher crystal sensitivities. This led to a preliminary connection between TKX-50 microscopic model parameters and macroscopic susceptibility. The results of the study can provide a reference for the design of subsequent experiments, and the research method can be extended to the research work on other energy-containing materials. [ABSTRACT FROM AUTHOR]

Crystals of the compound LiCo(SO4)OH were synthesised at low-hydrothermal conditions, and the crystal structure was determined and refined from single crystal X-ray diffraction data. LiCo(SO4)OH crystallises monoclinic, space group P21/c, Z = 4, a = 9.586(2), b = 5.425(1), c = 7.317(1) Å, β = 109.65(1)°, V = 358.3 Å3, wR2 = 0.0485 (2215 unique reflections, 78 variables). The structure is built from chains of edge-sharing, quite strongly bond-length and -angle distorted Co(OH)3O3 octahedra (< Co–O > = 2.126 Å), which are further linked by common corners, hydrogen bonds, and by properly shaped SO4 tetrahedra (< S–O > = 1.476 Å) to sheets parallel (100). These sheets are connected to a three-dimensional framework by sharing corners with distorted LiO4 polyhedra (< Li–O > = 1.956 Å). Apart from the isotypic sulfates of Mn2+ and Fe2+, only the molybdate LiCd(MoO4)OH crystallises isostructural with LiCo(SO4)OH. However, a very close structural relationship exists with the rare mineral hodgkinsonite, Zn2Mn(SiO4)(OH)2, yielding crystal chemically very uncommon topological equivalents of Zn2+ ≡ S6+ and Si4+ ≡ Li+, aside from the expectable substitution Mn2+ ≡ Co2+. Polarised optical absorption spectra of LiCo(SO4)OH reveal that the dominating spin-allowed 4T1(P) band system of Co2+ (d7 configuration) is strongly split up and covers a prominent part (~ 15,500–24,500 cm−1) of the visible spectral range, in accordance with the significant distortion of the Co(OH)3O3 polyhedron. The spectra are interpreted in terms of the Superposition Model of crystal fields, yielding a new set of intrinsic and interelectronic repulsion parameters for Co2+. [ABSTRACT FROM AUTHOR]

The present study is an attempt to model dynamic recrystallization (DRX) in a single phase metal using a mean field crystal plasticity (MFCP) based approach. A new empirical equation is proposed to model nucleation, in which the nucleation rate is a function of microstructure and plasticity descriptors that are known to affect DRX behavior, such as the temperature, strain rate, grain fineness and stored energy. Grains undergo nucleation when their dislocation density exceeds a threshold value. Subsequently, new grains grow based on the difference in stored deformation energy with respect to the average value over all grains. The MFCP-DRX model is able to correctly predict trends for the flow stress, dislocation density evolution, grain size evolution and kinetics across a range of temperatures and strain rates for uniaxial compression. Transition of the flow stress from single to multiple peaks is observed with increasing temperature and decreasing strain rate, thus comparing well against known DRX trends. The evolutions of crystallographic texture during DRX in uniaxial compression and plane strain compression are compared against experimental observations. A sensitivity analysis is conducted to understand the effect of variables on nucleation and growth. The competition between nucleation and growth dominated deformation in different strain regimes is analyzed in detail across various temperatures and strain rates. [ABSTRACT FROM AUTHOR]

Context: 3,4-Bisnitrofurazanfuroxan (DNTF) is a typical high energy density compound (HEDC), it has high crystal density and detonation parameters, but also high mechanical sensitivity. To decrease its mechanical sensitivity, the DNTF based polymer bonded explosives (PBXs) was designed. The pure DNTF crystal and PBXs models were established. The stability, sensitivity, detonation performance and mechanical properties of DNTF crystal and PBXs models were predicted. Results show that PBXs models containing fluorine rubber (F2311) and fluorine resin (F2314) have higher binding energy, meaning that DNTF/F2311 and DNTF/F2314 is relatively more stable. PBXs models have higher value of cohesive energy density (CED) than pure DNTF crystal, DNTF/F2311 and DNTF/F2314 have the highest value of CED, implying that the sensitivity of PBXs is effectively decreased, DNTF/F2311 and DNTF/F2314 is more insensitive. PBXs have lower crystal density and detonation parameters than DNTF, the energy density is declined, DNTF/F2314 has higher energetic performance than other PBXs. Compared with pure DNTF crystal, engineering moduli (tensile modulus, shear modulus, bulk modulus) of PBXs models are obviously decreased, but Cauchy pressure is increased, implying that the mechanical properties of PBXs is superior to pure DNTF component, the PBXs containing F2311 or F2314 have more preferable mechanical properties. Consequently, DNTF/F2311 and DNTF/F2314 have the best comprehensive properties and is more attractive among the designed PBXs, indicating that F2311 and F2314 are more advantageous and promising in ameliorating properties of DNTF. Methods: The properties of DNTF crystal and PBXs models were predicted through molecular dynamics (MD) method under Materials Studio 7.0 package. The MD simulation was performed with isothermal-constant volume (NVT) ensemble, and the force field was chosen as COMPASS force field. The temperature was set as 295 K, the time step was 1 fs and the total MD simulation time was 2 ns. [ABSTRACT FROM AUTHOR]

• Effect of temperature on the CRSSs of slips and twinning is evaluated in Mg single crystals. • Slips traces are used specially to define various deformation modes of Mg. • VPSC-GA modeling is proved to be effective to obtain the CRSSs of Mg. Magnesium (Mg) single crystal specimens with three different orientations were prepared and tested from room temperature to 733 K in order to systematically evaluate effects of temperature on the critical resolved shear stress (CRSS) of slips and twinning in Mg single crystals. The duplex non-basal slip took place in the temperature range from 613 to 733 K when the single crystal samples were stretched along the <0 1 ¯ 10> direction. In contrast, the single basal slip and prismatic slip were mainly activated in the temperature range from RT to 733 K when the tensile directions were inclined at an angle of 45° with the basal and the prismatic plane, respectively. Viscoplastic self-consistent (VPSC) crystal modeling simulations with genetic algorithm code (GA-code) were carried out to obtain the best fitted CRSSs of major deformation modes, such as basal slip, prismatic slip, pyramidal II , {10 1 ¯ 2} tensile twinning and {10 1 ¯ 1} compressive twinning when duplex slips accommodated deformation. Additionally, CRSSs of the basal and the prismatic slip were derived using the Schmid factor (SF) criterion when the single slip mainly accommodated deformation. From the CRSSs of major deformation modes obtained by the VPSC simulations and the SF calculations, the CRSSs for basal slip and {10 1 ¯ 2} tensile twinning were found to show a weak temperature dependence, whereas those for prismatic , slip and {10 1 ¯ 1} compressive twinning exhibited a strong temperature dependence. From the comparison of previous results, VPSC-GA modeling was proved to be an effective method to obtain the CRSSs of various deformation modes of Mg and its alloys. [ABSTRACT FROM AUTHOR]

The surface layer determines the physical properties of aviation materials and, based on these properties, the calculation of surface energy anisotropy can be implemented. Moreover, the value of the surface energy determines the service time and the destruction of aircraft structures surface layer, while the surface layer thickness determines the distance at which this process usually takes place. In this work, a new atomically smooth crystal empirical model is built without considering the surface roughness. This model can be used to theoretically predict the surface energy anisotropy and surface layer thickness of metals and other compounds, in particular the aviation materials. The work shows that the surface layer of an atomically smooth metal, like other compounds, consists of two nanostructured layers: d(I) and d(II). Having sufficient accuracy, the proposed model would allow the prediction of aviation materials performance properties without the need for ultrahigh vacuum or other complicated theoretical methods to analyze the surfaces of nanosystem atomic structures. [ABSTRACT FROM AUTHOR]

The purpose of the study was to identify and predict the optimized parameters for phosphoric acid production. This involved modeling the crystal reactor, UCEGO filter (as a detailed model of the filter is not available in Aspen Plus or other simulation software), and acid separator using Sci-Lab to develop Cape-Open models. The simulation was conducted using Aspen Plus and involved analyzing 10 different phosphates with varying qualities and fractions of P2O5 and other minerals. After a successful simulation, a sensitivity analysis was conducted by varying parameters such as capacity, filter speed, vacuum, particle size, water temperature for washing the filtration cake, flow of recycled acid and strong acid from the separator below the filter, flow of slurry to reactor 1, temperature in reactors, and flow of H2SO4, resulting in nearly one million combinations. To create an algorithm for predicting process parameters and the maximal extent of recovering H3PO4 from slurry, ANN models were developed with a determination coefficient of 99%. Multi-objective optimization was then performed using a genetic algorithm to find the most suitable parameters that would lead to a higher reaction degree (96–97%) and quantity of separated H3PO4 and lower losses of gypsum. The results indicated that it is possible to predict the influence of process parameters on the quality of produced acid and minimize losses during production. The developed model was confirmed to be viable when compared to results found in the literature. [ABSTRACT FROM AUTHOR]

Copyright of Basic Sciences Journal of Textile Universities / Fangzhi Gaoxiao Jichu Kexue Xuebao is the property of Basic Sciences Journal of Textile Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Additively manufactured stainless steels have become increasingly popular due to their desirable properties, but their mechanical behavior in structural parts is not yet fully understood. Specifically, the impact of columnar microstructures on fatigue behavior is still unclear. A typical directed energy deposition (DED)‐fabricated 316L stainless steel microstructure consists of distinct zones with equiaxed and columnar grains. To answer the question of how these zones of a DED‐fabricated 316L stainless steel microstructure affect the local mechanical behavior individually, such as the fatigue strength, stress/strain distribution, and fatigue life, crystal plasticity simulations are conducted to investigate the influence of microstructure on local mechanical behavior such as fatigue strength, stress/strain distribution, and fatigue life. The simulations find that columnar microstructures exhibit better fatigue strength than equiaxed structures when the load is parallel to the major axis of the columnar grains, but the strength decreases when the load is perpendicular. This study also uses machine learning to predict fatigue life, which shows good agreement with crystal plasticity modeling. The study suggests that the combined crystal plasticity–machine learning approach is an effective way to predict the fatigue behavior of additively manufactured components. [ABSTRACT FROM AUTHOR]

Modelling crystal growth is important for example in crystal engineering, materials science, and the life sciences. Molecular modelling techniques can provide fundamental insights into the atomic processes underlying crystal growth but do not always give direct information about growth rates and growth modes on spatial and temporal scales relevant in nature and for applications. The phase-field (PF) approach is a relatively simple model that can provide results on length and time scales directly comparable to experiments, but it has not extensively been employed to investigate crystallization of ionic solids, and not many quantitative results have been reported. In the present study we model the growth of cubic NaCl crystals in two dimensions. We have used small crystal seeds with an appropriate anisotropy term to investigate both the growth speed and the growth mode. Results are compared to experimental data from the literature. The PF model displays the concentration dependent transition from compact to non-compact growth of NaCl reasonably well on spatial and temporal scales that are not easily accessible with other theoretical models. [ABSTRACT FROM AUTHOR]

We optimize a numerical time‐stabilization routine for a class of phase‐field crystal (PFC) models of solidification. By numerical experiments, we demonstrate that our simple approach can improve the accuracy of underlying time integration schemes by a few orders of magnitude. We investigate different time integration schemes. Moreover, as a prototypical example for applications, we extend our numerical approach to a PFC model of solidification with an explicit temperature coupling. [ABSTRACT FROM AUTHOR]

Intermittent mechanical loads combined with high temperatures appear during the operation of turbines in jet engines or in power plants, which can lead to high-temperature fatigue or to thermomechanical fatigue. Since the assessment of fatigue properties is a complex and time-consuming process, it is essential to develop validated material models that are capable of predicting fatigue behavior, thus allowing the extrapolation of experimental results into a broader range of thermomechanical conditions. To accomplish this, two representative volume elements (RVEs), mimicking the typical microstructure of single crystal Ni-based superalloys and polycrystalline austenitic steels, respectively, are introduced. With the help of these RVEs, the temperature and deformation-dependent internal stresses in the microstructure can be taken into account. In the next step, phenomenological crystal plasticity models are implemented and parameterized for cyclic deformation of these two materials. The RVE, constitutive model, and the material parameters for the Ni-based superalloy are taken from a former study. For the austenitic steel, however, an inverse procedure has been used to identify its material parameters based on several isothermal fatigue tests in a wide temperature range. With the identified material parameters, a valid description of the isothermal fatigue behavior at different temperatures is possible. The most important conclusion from the comparison of the isothermal fatigue behavior of the two different materials is that the kinematic hardening, which is responsible for the shape of the hysteresis loops, is entirely described by the internal stresses within the typical microstructure of the Ni-based superalloy, which is modeled in a scale-bridging approach. Hence, no additional terms for kinematic hardening need to be introduced to describe the cyclic plasticity in the superalloy. For the austenitic steel, in contrast, the Ohno–Wang model for kinematic hardening needs to be considered additionally to the internal stresses in the polycrystalline microstructure to obtain a correct description of its cyclic plasticity. [ABSTRACT FROM AUTHOR]

A numerical investigation of the kink strengthening mechanism in long-period stacking ordered magnesium alloy is presented. A higherorder gradient crystal plasticity model is introduced, and the reproducing kernel particle method is adopted for the numerical procedure. The specimen, including a kink band with several kink angles, which is defined as the angle between the inside and outside of the kink band, is considered. A simple shear analysis is conducted to evaluate the kink strengthening due to the kink band. The numerical results suggest two main origins of kink strengthening, namely, orientation and defect strengthening. The former is caused by the spatial distribution of the slip direction due to kink, and the latter is the strengthening induced by crystal defects around the kink boundary. The amplitude of kink strengthening depends on the kink angle, and an optimal kink angle, which maximizes the kink strengthening, might exist. The kink strengthening exhibits a HallPetch- like behavior, i.e., the correlation between the inverse of the square root of the kink band width and flow stress is almost linear. [ABSTRACT FROM AUTHOR]

The grain structure of metals changes significantly during severe plastic deformation (SPD), and grain refinement is the main process associated with SPD at low homologous temperatures. Products made of ultrafine-grained materials exhibit improved performance characteristics and are of considerable industrial interest, which generates a need for the creation of comprehensive grain refinement models. This paper considers the integration of the ETMB (Y. Estrin, L.S. Toth, A. Molinari, Y. Brechet) model, which describes the evolution of an average cell size during deformation into the two-level statistical crystal plasticity constitutive model (CM) of FCC polycrystals. The original relations of the ETMB model and some of its modifications known from the literature were analyzed to obtain an accurate, physically admissible description of the grain refinement process. The characteristics of the grain substructure determined with the framework of the advanced ETMB model were taken into account in the CM in a hardening law. By applying the CM with the integrated ETMB model, numerical experiments were performed to simulate the changes in the grain structure of copper during equal channel angular pressing (ECAP) at room temperature. The results obtained are in good agreement with the experimental data. The ideas about further development of the proposed model are outlined. [ABSTRACT FROM AUTHOR]

The cocrystallization of trans-[PtI2(NCN(CH2)5)2] and iodoform (CHI3) yields crystalline adduct trans-[PtI2(NCN(CH2)5)2]∙2CHI3, the structure of which was studied via single-crystal X-ray diffractometry (XRD). In the XRD structure of trans-[PtI2(NCN(CH2)5)2]∙2CHI3, apart from rather predictable C–H∙∙∙I hydrogen bonds (HBs) and C−I∙∙∙I halogen bonds (XBs) with the iodide ligands, we identified C–I∙∙∙Pt metal-involving XBs, where the platinum center functions as an XB acceptor (that includes a metal dz2-orbital) toward the σ-holes of I atoms of CHI3. DFT calculations (PBE-D3/jorge-TZP-DKH with plane waves in the GAPW method) were carried out in the CP2K program for isolated molecules, complex–iodoform clusters, and crystal models with periodic boundary conditions, where the noncovalent nature and the existence of the interactions were confirmed using charge analysis, Wiberg bond indexes, and QTAIM topology analysis of electron density, whereas the philicities of the noncovalent partners were proved using charge analysis, electron localization function, electron density deformation, and one-electron potential projections, as well as electron density/electrostatic potential profiles for cluster models and electrostatic potential surfaces (ρ = 0.001 a.u.) for isolated molecules. [ABSTRACT FROM AUTHOR]

A new NMR method for the structure elucidation of lithium compounds under solution‐like conditions is presented. It is based on the measurement of 7Li residual quadrupolar couplings (RQCs) in a stretched polystyrene (PS) gel, and comparison to RQCs predicted from crystal or DFT‐derived model structures in combination with alignment tensors derived from one‐bond 1H,13C residual dipolar couplings (RDCs). The method was applied to five lithium model complexes containing monoanionic, bidentate bis(benzoxazole‐2‐yl)methanide, bis(benzothiazole‐2‐yl)methanide and bis(pyridyl)methanide ligands, of which two are first introduced in this work. In agreement with the crystalline state, four complexes are monomeric with Li coordinated fourfold by two additional THF molecules, whereas in one complex bulky tBu groups only provide space for one additional THF molecule. [ABSTRACT FROM AUTHOR]

This work aims to provide a comprehensive review of the continuum models of the phase behaviors of liquid crystal networks (LCNs), novel materials with various engineering applications thanks to their unique composition of polymer and liquid crystal. Two distinct behaviors are primarily considered: soft elasticity and spontaneous deformation found in the material. First, we revisit these characteristic phase behaviors, followed by an introduction of various constitutive models with diverse techniques and fidelities in describing the phase behaviors. We also present finite element models that predict these behaviors, emphasizing the importance of such models in predicting the material's behavior. By disseminating various models essential to understanding the underlying physics of the behavior, we hope to help researchers and engineers harness the material's full potential. Finally, we discuss future research directions necessary to advance our understanding of LCNs further and enable more sophisticated and precise control of their properties. Overall, this review provides a comprehensive understanding of the state-of-the-art techniques and models used to analyze the behavior of LCNs and their potential for various engineering applications. [ABSTRACT FROM AUTHOR]

The calculation of the number of ice crystals for the model of frazil ice evolution is very important and affects the whole frazil events. In this paper, the general formula for the number of frazil ice crystals was established considering secondary nucleation, flocculation, gravity and turbulent entrainment, and ice crystals by melting. Meanwhile, two physical processes of secondary nucleation and flocculation were expressed by introducing critical impact velocity and the probability of flocculation from previous models. It has been found that the simulation results of frazil ice evolution are in good agreement with the experimental data and actual project. Then, Sobol method is carried out to judge parameters' influence degree, which found the number of nuclei produced E is the most sensitive and has the greatest influence on the model results. In addition, sensitivity analysis of these parameters shows that they can affect the maximum supercooling and the period of supercooling. Therefore, the calculation method of the number of ice crystals is applied, which provides technical support for exploring the water temperature and internal relationship of frazil ice evolution. [ABSTRACT FROM AUTHOR]

The specific features of application of a low-energy atomic-force microscope (AFM) for studying the dynamic process of face growth in terms of the fluctuation model of crystal growth are discussed. It is shown that the probe interaction with an area of growing crystal surface on the time scale characteristic of a sequence of free energy fluctuations is a limiting factor for constructing an image of growing face surface. Agreement between the phenomenological and quantum (according to the uncertainty relation) descriptions of the effect of limiting magnification for a growing crystal face in an AFM is demonstrated. Specific features of detecting a growth stage on a crystal face using a transmission/scanning high-resolution electron microscope in a gas medium are also discussed. The effect of ultimate magnification when observing crystal growth in an АFМ is a basis for discussing the concept of the transient state of matter in the topochemical reaction of crystal growth and the phenomenon of building particle. [ABSTRACT FROM AUTHOR]

The bendability of extruded profiles of an age hardenable aluminum alloy is investigated using mechanical tests on flat tensile specimens and bending specimens. Two profile geometries are considered, where the profiles exhibit different grain structures. The microstructure of the profiles in terms of the crystallographic texture and constituent particles is otherwise comparable. While the tensile properties are not that different for the two profiles, their bendability is strongly dependent on the grain structure and is about twice as high for one profile than for the other. A newly proposed coupled damage and single crystal plasticity model is used in finite element analyses of the mechanical tests to investigate the influence of the grain structure on the bending behavior, and the numerical results are compared to the experimental tests. The crystallographic texture and the grain morphology of the profiles, found by the electron back-scatter diffraction technique, are explicitly represented in the finite element models. The crystal plasticity simulations capture the difference in the bendability of the two profiles, and in agreement with the experiments predict a considerably higher bendability for one of the profiles. It is found that the grain structure affects the shear band formation in these profiles, but also the local texture where the shear bands are located is important for crack initiation and propagation as grains with certain crystallographic orientations may have a higher fracture resistance. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomer-based actuators (LCEAs) exhibit large, reversible deformation, which demonstrates superior advantages in developing remote controlled, light-weighted soft robots. However, deformation of LCEAs undergoes complicated physical dynamics and exhibits highly nonlinear hysteretic characteristics, posing challenges in the realization of related applications. It is necessary to develop a dynamic model that captures the characteristics of LCEAs. With this purpose, this paper proposes a dynamic modelling approach for LCEAs to provide a hybrid model for LCEAs with reduced computational complexity and high precision. In the research, a modelling scheme based on a physics-phenomenon-combined approach for LCEAs is proposed, which considers the elastic free energy, the nematic free energy and dissipation of the LCEA. Physics-based models are then developed to describe these energies. Meanwhile, a phenomenon-based model is proposed to characterise the hysteresis as a component of the nematic free energy. The above models are combined together to provide the final hybrid model for the LCEA. To verify the proposed model, a photo-responsive LCEA experimental platform is established and experiments are conducted. Model parameters are identified based on the nonlinear least-squares method. The experimental results demonstrate the proposed model as an excellent representative to characterise LCEAs' dynamic behaviours. [ABSTRACT FROM AUTHOR]

A crystal chemical analysis of the 3d-metal benzoate- and phenylacetate-containing compounds is carried out in terms of the stereoatomic crystal structure model using characteristics of the Voronoi–Dirichlet polyhedra. Coordination types of benzoate and phenylacetate anions toward the transition metals from Ti to Zn are considered. The influence of the coordination type on the characteristics of M–O bonds in the crystal structures is revealed. The electron-donating ability of benzoate and phenylacetate anions toward 3d metals is quantitatively estimated using the 18-electron rule. [ABSTRACT FROM AUTHOR]

In this paper, an accurate numerical modelling of nematic liquid crystal for the inverted microstrip phase shifter is presented. Four kinds of liquid crystal with different values of anisotropy have been studied using the conventional simplified liquid crystal model where the liquid crystal is usually assumed isotropic and homogeneous. The S parameters of the phase shifter based on these liquid crystals are simulated. Moreover, considering the anisotropy and inhomogeneous of liquid crystal, the accurate modelling of nematic liquid crystal BL006 applied in the phase shifter under the voltage is calculated. The distribution of the director and permittivity of liquid crystal at the steady state under different voltages is obtained. Based on the accurate modelling results of liquid crystal BL006, the phase shifter is remodelled and simulated. Compared with that of the simplified model, the maximum differential phase shift of the phase shifter based on the liquid crystal BL006 in the accurate model at the centre frequency of 20 GHz was reduced by about 36:5°, and this error will increase with the increasing of the frequency. This numerical modelling method of liquid crystal also can be used in the design of other microwave devices based on nematic liquid crystal. [ABSTRACT FROM AUTHOR]

The crystal structures of a series of nitro- and tetrazolopyrazines were modeled quantum chemically and by the atom-atom potential method and their thermochemical, ballistic, and detonation characteristics were calculated. All compounds are characterized by rather high enthalpies of formation in the solid phase and by moderate molecular crystal densities (except 2,3,5,6-tetranitropyrazine having a high density of 1.995 g cm−3). The possibility to use the title compounds as high-energy materials was assessed. [ABSTRACT FROM AUTHOR]

{ 10 1 ¯ 2 } twins were introduced into the magnesium (Mg) plate AZ31 via pre-rolling along its transverse direction. The plates, both with and without the pre-induced { 10 1 ¯ 2 } twins, were subjected to uniaxial tension along different directions. Using crystal plasticity modeling, we found that the strengthening effect of the pre-induced { 10 1 ¯ 2 } twins on the macroscopic flow stress primarily arised from the increased slip resistance caused by the boundaries, rather than the orientation hardening due to the twinning reorientation (although the latter did make its contribution in some specific loading directions). Besides, the pre-existing { 10 1 ¯ 2 } twins were found, by both experiments and simulation, to promote the activity of prismatic 〈a〉 and pyramidal in the parent matrix of the material. Further analysis showed that the enhanced non-basal slip activity is related to the { 10 1 ¯ 2 } twin boundaries' low micro Hall-Petch slope ratios of non-basal slips to basal slip. With the critical resolved shear stress (CRSS) obtained from crystal plasticity modeling and the orientation data from EBSD, a probability-based slip transfer model was proposed. The model predicts higher slip transfer probabilities and thus lower strain concentration tendencies at { 10 1 ¯ 2 } twin boundaries than that at grain boundaries, which agrees with the experimental observation that the strain localization was primarily associated with the latter. The present findings are helpful scientifically, in deepening our understanding of how the pre-induced { 10 1 ¯ 2 } twins affect the strength and slip activity of Mg alloys, and technologically, in guiding the design of the pre-strain protocol of Mg alloys. [ABSTRACT FROM AUTHOR]

Parsing the effect of slip-twin interactions on the strain rate and thermal sensitivities of Magnesium (Mg) alloys has been a challenging endeavor for scientists preoccupied with the mechanical behavior of hexagonal close-packed alloys, especially those with great latent economic potential such as Mg. One of the main barriers is the travail entailed in fitting the various stress–strain behaviors at different temperatures, strain rates, loading directions applied to different starting textures. Taking on this task for two different Mg alloys presenting different textures and as such various levels of slip-twin interactions were modeled using visco-plastic self-consistent (VPSC) code. A recently developed routine that captures dislocation transmutation by twinning interfaces on strain hardening within the twin lamellae was employed. While the strong texture was exemplified by traditional rolled AZ31 Mg alloys, the weak texture was represented by ZEK100 Mg alloy sheets. The transmutation model incorporated within a dislocation density based hardening model showed enhanced flexibility in predicting the complex strain rate and thermal sensitive behavior of Mg textures' response to various mechanical loading schemes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)