Polycrystalline Research Articles

Scrolled Poly(L-Lactic Acid) Single Crystals via Chain End-Induced Symmetry-Breaking.

Single crystals that do not obey translational symmetry have been reported in various material systems. In polymers, twisted crystals are typically formed in banded spherulites, while a class of non-flat polymer single crystals (PSCs) has been observed. Herein, we report the formation of scrolled single crystals of biodegradable polymer poly(L-lactic acid) (PLLA). While classical 2-dimensional single crystals formed in solution-crystallized PLLA are flat, we show that PLLA crystals bend into scrolls when the polymer molecular weight is low. The formation of these unique scrolled PLLA single crystals depends on polymer chain ends and the polymer molecular weight. This work, therefore, demonstrates a new mechanism to break translational symmetry in PSC growth.

Influence of point defects on intergranular fracture of steel

At present, it has been established that the ageing process of pipe steel is multistage. The first stage is characterized by the release of carbon atoms from the metal grains. The second stage is determined by the removal of inter-nodal atoms to the grain boundaries. This removal mechanism is related to the diffusion of carbon through the inter-domain space, facilitated by point defects such as vacancies. The most optimistic estimates give an unrealistically long time of the ageing process of steel. Thus the diffusion mechanism remains unclear.The aim of this study is to construct a mechanism that would adequately describes this phenomenon. The authors believe such a mechanism should be related to point defects (vacancies). The leading method used in this research is theoretical analysis, which has led to the proposal of an effective way of influence of point defects in intergranular corrosion failure of steel is proposed.Under conditions of uphill diffusion in the linear approximation, mass transfer develops slowly and cannot enrich the adjacent grain boundary layers with impurities. The presence of defects makes the diffusion nonlinear.This study considers thermodefects generated by a temperature gradient. Based on changes in the magnetic properties of the samples, conclusions about the formation of the structure with the participation of carbon impurities displaced in the process of hydrogen introduction were made.The results of this study can be used in the development of methods of increase of service life of pipe steels.

Formation and Magnetic Properties of Transition Metal Atomic Chains on Monolayer MoS2 Grain Boundaries: A First-Principles Study.

Magnetic one-dimensional nanostructures show great potential in spintronics and can be used as basic building blocks for magnetic materials and devices with multiple functions. In this study, transition group atomic chains (V, Cr, Mn, Fe, Co, and Ni) are introduced into nonmagnetic MoS2 with a 4|8ud-type grain boundary. Based on first-principles calculations, the V atomic chains show good thermodynamic stability and can self-assemble along the grain boundary direction. The formation of V, Cr, Mn, and Ni atomic chains can induce magnetism into a 4|8ud-type MoS2 system through typical d-d and p-d interactions. This joint effect of transition metal doping and grain boundaries on the magnetism of monolayer MoS2 is of great significance for exploring the electromagnetic properties of monolayer MoS2 for the development of electronic devices.

An Exploratory Study of the Surface Integrity of Various FRP Composites in Face Milling Operation

The use of glass, carbon and hybrid /glass/carbon epoxy polymer composites is widely used in the automotive, manufacturing and aerospace sectors. Milling is a secondary production process in which the final shape of the product is produced with the desired shape and high dimensional accuracy. The objective of this study is to enhance our knowledge of the machinability properties of composite materials in the secondary manufacturing industry. In this research study, performing face milling operations with different tools on bidirectional (BD) glass, unidirectional (UD) glass, carbon/epoxy, and glass/carbon/epoxy (hybrid epoxy) polymer composites. This experimental work derives conclusions that contribute to the improvement of the milling process for better surface quality. Taguchi’s L16 Design of Experiments (DOE) and Analysis of Variance (ANOVA) are used to determine the effect of tool type, speed of spindle, rate of feed, cut depth on surface roughness and delamination factor. And it was concluded that glass/carbon hybrid epoxy polymer laminates showed improved surface quality when milled with a Poly Crystalline Diamond (PCD) tool at parametric combinations of rate of feed is 300 mm/min, speed of spindle is 1000 rpm, and cutting depth is 0.5 mm. In addition, the experimental results of the scanning electron microscope examination were also verified. And found excellent machined surface quality and least damage with the above optimal process parameter combinations.

Fractional time differential equations as a singular limit of the Kobayashi–Warren–Carter system

This paper is concerned with a singular limit of the Kobayashi–Warren–Carter system, a phase field system modelling the evolutions of structures of grains. Under a suitable scaling, the limit system is formally derived when the interface thickness parameter tends to zero. Different from many other problems, it turns out that the limit system is a system involving fractional time derivatives, although the original system is a simple gradient flow. A rigorous derivation is given when the problem is reduced to a gradient flow of a single-well Modica–Mortola functional in a one-dimensional setting.

Microstructural Evolution and Mechanical Property Enhancement in WAAM Components

Abstract Wire arc additive manufacturing (WAAM) is increasingly being recognized as a favourable method for producing large-scale products. The microstructural evolution during the solidification of molten pool in WAAM is influenced by factors such as heat input and the deposited layer sequence. In this study, the impact of different layering sequences on grain growth, microstructure, and mechanical properties was investigated by depositing Inconel 825 alloy using gas metal arc welding. Different layering sequences were employed to minimize the development of columnar grains that typically outcome from oscillating beads and bead upon bead within a single layer. The unidirectional heat flow in conventional layering techniques encourages grain growth in the direction of the heat source, with grains forming at the fusion boundaries and growing upwards. At the interface between previously solidified beads and the liquid metal, nucleation and epitaxial grain growth occur, prominent to the formation of transverse columnar grains, with their size determined by the grain structure of the preceding layer. While traditional stacking sequences tend to produce columnar grains, a zigzag layering approach was found to refine grain growth by disrupting the direction of heat flow and grain development. This resulted in smaller, more fragmented grains, which enhanced the isotropic properties of the material. The study further demonstrated that the anisotropic behavior of wire arc additively manufactured components is closely related to grain growth direction and size, both of which are significantly influenced by the layering sequence. The zigzag layering sequence not only improved hardness and tensile strength compared to conventional layering methods but also enhanced the resolution and linearity of the deposited walls.

Effect of deformation nanostructuring on ion-beam erosion of metals

The effect of deformation nanostructuring of copper, nickel, and titanium on ion-induced morphology and sputtering under 30 keV argon ions high-fluence irradiation along the normal to the surface has been studied. Sputtering of a layer commensurate with the size of metal grains leads to a uniform cone-shaped relief, the stationary erosion of which occurs with significant redepositing of atoms.

Unraveling the Composition Effects in Chemo-Mechanical Behavior for Single-Crystal Ni Rich Cathodes

Nickel-rich lithium layered oxides (LiNi x Mn y Co z O2 (NMC), x + y + z = 1, x ≥ 0.6) with high accessible capacity, have received tremendous attention as the most promising cathode candidate for next-generation lithium-ion batteries1. To obtain cathode materials with superior electrochemical performance, substantial efforts have focused on optimizing materials’ chemical compositions. However, regardless of chemical compositions, most commercial NMC materials are typically agglomerates composed of primary nanograins (polycrystalline (PC) NMC) which suffer from severe anisotropic expanding or shrinking and thus rapid mechanical failure in the form of intergranular cracking2. To enhance the structural stability, single crystal (SC) NMC with pore-free and high-strength micron-scale particles have received considerable attention3. Owing to the changes in mechanical properties and degradation mechanisms, uncertainties persist regarding the applicability of established compositional design principles and structural degradation indicators in PC Ni rich cathodes to the newly developed SC counterparts4-5. Here we elucidate the intricate correlation between chemical composition and structural properties in SC Ni-rich cathodes using Co-free and Mn-free cathodes as the models. In this case, Mn and Co exhibit significantly different roles for SC cathodes in electrochemical behaviors compared to their PC analogues. By leveraging multi-scale and high dimensional characterization techniques, we reveal the composition effects in lattice strain generation, phase evolution and microcrack formation. This study deepens understanding of the relationship between chemical composition and chemo-mechanical behaviors for SC Ni rich cathodes, contributing to relevant development of rational design strategies and refined characterization methodology. References M. Li, J. Lu, Z. Chen, K. Amine. Adv. Mater. 2018, 30, e1800561.T. Liu, L. Yu, J. Lu, T. Zhou, X. Huang, Z. Cai, A. Dai, J. Gim, Y. Ren, X. Xiao, M. V. Holt, Y. S. Chu, I. Arslan, J. Wen, K. Amine. Nat. Commun. 2021, 12, 6024.J. Langdon, A. Manthiram. Energy Storage Mater. 2021, 37, 143-160.T. Liu, L. Yu, J. Liu, J. Lu, X. Bi, A. Dai, M. Li, M. Li, Z. Hu, L. Ma, D. Luo, J. Zheng, T. Wu, Y. Ren, J. Wen, F. Pan, K. Amine. Nat. Energy 2021, 3, 277-286.A. Aishova, G-T. Park, C. S. Yoon, Y-K Sun. Adv. Energy Mater. 2020, 10, 1903179.

Developing Aqueous Processed Transition Metal Oxide Cathodes with Sustainable Binders for High Energy Density Lithium-Ion Batteries from Lab Scale to Manufacturing Scale

Transitioning toward more sustainable materials and manufacturing methods is critical to continue supporting the rapidly expanding market for lithium-ion batteries (LIBs). Meanwhile, energy storage applications are requiring higher power and energy densities with demanding performance targets like fast charging and a wide range of operating voltages. Alongside high-performance demands, environmental considerations such as organic solvent use, low abundance of Co and other mining related issues, urgently need to be addressed by the LIBs community [1]. High voltage spinel LiNi0.5Mn1.5O4 (LNMO) is considered a highly promising cathode candidate for the next generation high performance LIBs due to a high energy density (650 W H kg -1), high operating voltage (∼4.7 V vs Li), low environmental impact, and low-cost fabrication [2]. However, severe capacity degradation during cycling has impeded wide application and commercialization.In this study, we investigated LNMO thoroughly as a cathode material using only aqueous processing, covering the processing range from small scale to the research pilot line level. Aqueous electrode processing is highly critical to eliminate organic solvent use in LIBs production. On the anode side, aqueous processing has already been established on the industrial level, whilst cathode aqueous processing still needs to be tuned to reach to the same level of feasibility. The main challenge in aqueous processing of transition metal oxides is the high surface sensitivity towards water, resulting in Li/proton exchange. Consequently, pronounced Li+ loss is observed on the electrode during cycling. In literature, acid treatment is one of the most common approaches to avoid this phenomenon during slurry preparation [3]. In this work, we investigate different crystal structure with combination of two binders. Understanding the impact of the different crystal structure of LNMO particles on lithium leaching during slurry processing is one the targets of the study. On the particle level, single, poly crystalline and mixed of single and poly crystal powders are characterized to select the most promising candidate in terms of processing and cycling performance. Two different binder systems were studied, including carboxymethyl cellulose (CMC) with acrylic based binder as baseline for water-borne cathodes, and Na-Alginate as a more sustainable binder option specifically for LNMO.The formulation development started at the laboratory scale with slurries characterized with pH control and regarding their rheological behavior. Detailed electrochemical analysis with cycling and electrochemical impedance spectroscopy (EIS) was performed along with comprehensive surface characterization and scanning electron microscopy (SEM) before cycling and post-mortem. Subsequently, the most promising candidates were successfully upscaled to the research pilot line. By characterizing three crystal structures of LNMO with two binders, we demonstrate the capabilities of LNMO as an active material using the most sustainable processing conditions. Depending on the crystal structure, single crystal LNMO with Na-Alginate binder was found to be the most promising candidate (capacity retention ∼130 mAh g -1 after 150 cycles), especially for fast charging applications. This study is to serve as guideline for better understanding of LNMO and its aqueous processability.

Understanding the Failure Mechanisms of LiMn2O4/Graphite Pouch Cells Using Isothermal Microcalorimetry

LiMn2O4 (LMO) cells are known to suffer from the electrochemical oxidation and dissolution of manganese from the positive electrode into the electrolyte and subsequent transport to the negative electrode, where the metals are deposited on the solid electrolyte interphase (SEI)1-3. Pouch cells of polycrystalline and single crystal spinel LMO / artificial graphite (AG) were tested under varying conditions of temperature and upper cutoff voltage to investigate degradation mechanisms. Mn dissolution from the positive electrode and deposition onto the graphite negative electrodes immediately after formation was found to be significantly suppressed by operating cells at -10°C during the formation cycle and reducing the upper cutoff voltage. A formation cycle at an elevated temperature of 70°C greatly increases the Mn deposition and gas generation from electrolyte reduction after just a single cycle and had long term effects at increasing lifetime gassing and Mn deposition. The cold formation advantage disappeared once all cells were cycled at 40°C, with similarly terrible cycle life (60 - 200 cycles) regardless of formation conditions. Studying fully lithiated graphite (LiC6) extracted from LMO cells in an isothermal microcalorimeter (IMC), we found that the parasitic heat flow associated with electrolyte reduction and graphite delithiation increased for anodes with significant Mn deposition. Therefore, Mn deposition on the negative electrode causes cell failure by compromising the anode passivation, increasing lithiated graphite-electrolyte reactivity and thereby accelerating the lithium inventory loss due to electrolyte reduction on the Mn sites on the negative electrode.Figure 1: Correlating variables critical to the degradation mechanism of LMO/AG cells for polycrystalline (PC) and single crystal (SC) LMO cells. (a) Arrhenius plot of Mn deposition on the graphite electrode with exponential dependence on formation temperature. (b) Formation gas from electrolyte reduction vs Mn deposition. (c) Parasitic heat flow from lithiated graphite reacting with electrolyte in pouch bags measured by isothermal microcalorimetry as a function of Mn deposition. (d) Cell capacity loss and heat energy dissipation during voltage hold experiments as a function of Mn deposition.

(Invited) Why Poly-OS IGO TFT Exhibits Mobilities >50 cm2/Vs

Poly-OS, a poly-crystalline oxide semiconductor, is one candidate for providing high-mobility backplane thin-film transistors (TFTs) for flat panel displays. Existing amorphous oxide semiconductor (Oxide) TFTs, like amorphous silicon (a-Si) are easy to fabricate in large areas. In addition, Oxide offers low power consumption due to their low off-leakage current. On the other hand, they have lower mobility than low temperature poly-crystalline silicon (LTPS), which is mainly used in today's small- and medium-sized displays. Poly-OS technology significantly improves mobility and enables high performance comparable to LTPS. This makes it possible to create products that combine the performance of existing backplane technologies (a-Si, Oxide, and LTPS) In fact, TFT mobility of 55.7 cm2/Vs has been achieved on a large-area substrate of the G6(1500×1800 mm) line by its sophisticated technology1 and IGO2 including indium, gallium and oxygen which one of Poly-OS material developed by us. IGO is characterized by its ability to generate a poly-crystalline state using the conventional process (450 ℃ or lower) like existing oxide semiconductors. By using this poly-crystalline structure in the active layer, it is possible to maximize the inherent electron mobility of oxides. X-ray diffraction peaks observed in IGO film are in good agreement with the In2O3 crystalline bixbyite structure (space group Ia-3), and cross-sectional TEM and the fast Fourier transform (FFT) pattern indicate that the film has single crystal structure in a grain. Hall mobility(μ H) of IGO films is remarkably higher than that of amorphous Oxide in high carrier concentration: nH region (> 1 × 1019 cm-3). The μ H - nH trend is important in considering the field-effect mobility for carriers accumulated by the gate electric field. As a result, it is expected that IGO TFT which has carrier concentration more than 1 × 1019 cm-3 by the gate field exceed the mobility of 50 cm2/Vs. We will explain why poly-OS exhibits high TFT mobilities over 50 cm2/Vs despite it exhibits μH as low as 20 cm2/Vs when nH corresponds to those used in TFT channels.

Strengthening of HCP metals with split basal texture through non-dislocation hardening mechanism

Work hardening mechanisms in metals have been extensively studied with a focus on the motion of dislocations and their inhibition, and these studies have provided in-depth knowledge of the relationship between dislocations and work hardening; however, other factors also influence the work hardening mechanism. When polycrystalline metals deform, the shape of the grain boundaries must match between neighboring grains, resulting in deformation constraint between the grains. Hexagonal close-packed (HCP) single crystals exhibit greater plastic anisotropy than those in body-centered cubic (BCC) and face-centered cubic (FCC) crystals, leading to stronger deformation constraint between grains in polycrystalline HCP metals. This study investigates the effects of deformation constraint between grains on macroscopic stress–strain curves by reproducing the deformation of HCP metals using crystal plasticity finite element analysis. The results indicate that in polycrystalline HCP metals, the non-dislocation effect, constraint between grains, also significantly affects work hardening.

Femtosecond Laser-Induced Recrystallized Nanotexturing for Identity Document Security With Physical Unclonable Functions.

Counterfeit identity (ID) documents pose a serious threat to personal credit and national security. As a promising candidate, optical physical unclonable functions (PUFs) offer a robust defense mechanism against counterfeits. Despite the innovations in chemically synthesized PUFs, challenges persist, including harmful chemical treatments, low yields, and incompatibility of reaction conditions with the ID document materials. More notably, surface relief nanostructures for PUFs, such as wrinkles, are still at risk of being replicated through scanning lithography or nanoimprint. Here, a femtosecond laser-induced recrystallized silicon nanotexture is reported as latent PUF nanofingerprint for document anti-counterfeiting. With femtosecond laser irradiation, nanotextures spontaneously emerge within 100ms of exposure. By introducing a low-absorption metal layer, surface plasmon polariton waves are excited on the silicon-metal multilayer nanofilms with long-range boosting, ensuring the uniqueness and non-replicability of the final nanotextures. Furthermore, the femtosecond laser induces a phase transition in the latent nanotexture from amorphous to polycrystalline state, rather than creating replicable relief wrinkles. The random nanotextures are easily identifiable through optical microscopy and Raman imaging, yet they remain undetectable by surface characterization methods such as scanning electron and atomic force microscopies. This property significantly hinders counterfeiting efforts, as it prevents the precise replication of these nanostructures.

Building Earth with pebbles made of chondritic components

Pebble accretion provides new insights into Earth’s building blocks and early protoplanetary disk conditions. Here, we show that mixtures of chondritic components: metal grains, chondrules, calcium-aluminum-rich inclusions (CAIs), and amoeboid olivine aggregates (AOAs) match Earth’s major element composition (Fe, Ni, Si, Mg, Ca, Al, O) within uncertainties, whereas no combination of chondrites and iron meteorites does. Our best fits also match the ε54Cr and ε50Ti values of Earth precisely, whereas the best fits for chondrites, or components with a high proportion of E chondrules, fails to match Earth. In contrast to some previous studies, our best-fitting component mixture is predominantly carbonaceous, rather than enstatite chondrules. It also includes 16 wt% of early-formed refractory inclusions (CAIs + AOAs), which is similar to that found in some C chondrites (CO, CV, CK), but notably higher than NC chondrites. High abundances of refractory materials is lacking in NC chondrites, because they formed after the majority of refractory grains were either drawn into the Sun or incorporated into terrestrial protoplanets via pebble accretion. We show that combinations of Stokes numbers of chondritic components build 0.35–0.7 Earth masses in 2 My in the Hill regime accretion, for a typical pebble column density of 1.2 kg/m2 at 1 au. However, a larger or smaller column density leads to super-Earth or moon-mass bodies, respectively. Our calculations also demonstrate that a few My of pebble accretion with these components yields a total protoplanet mass inside 1 au exceeding the combined masses of Earth, Moon, Venus, and Mercury. Accordingly, we conclude that pebble accretion is a viable mechanism to build Earth and its major element composition from primitive chondritic components within the solar nebula lifetime.

Ore formation in mantle peridotites before and after emplacement: review and new perspective

Generation of ore deposits in and around mantle peridotite (serpentinite) massifs is reviewed and summarized, and future studies are discussed as well. Podiform chromitites are essentially formed by magma–peridotite (mainly harzburgite) reaction and subsequent magma mixing at the upper mantle. The UHP chromitite is, however, possibly formed by deep recycling of the low-pressure one formed in the upper mantle. Seawater, which contains Cl, is potentially able to dissolve and transport Cr and precipitate chromian spinel. Chromitite formation in the mantle wedge by slab fluids is possible but has not been well examined. Olivine in peridotites is potentially an important source of some elements (iron and related transition metals), which are liberated upon its breakdown during serpentinization. They are sometimes precipitated in situ as minute grains of oxides, sulfides or metals in serpentinite, but sometimes transported via hydrothermal solutions responsible for serpentinization and concentrated to form ores. Magnetite veins in serpentinite, possibly as well as Co–Ni arsenides along the serpentinite–diorite boundaries of the Bou-Azzer ophiolite, provide a good example. Precipitation of Mn nodules and other ores from the seafloor is possibly related to circulated seawater through peridotite emplaced in the crust. This issue should be examined thoroughly in the future.

Metallic material microstructure grain size measurements from backscattering signals in ultrasonic array data sets

Ultrasound backscattering signals from material microstructures can be used to evaluate the material microstructure grain size. This typically involves making pulse-echo immersion measurements at multiple locations using a focused ultrasonic transducer in order to obtain an accurate estimate of the root-mean-square amplitude of the back-scattered signal at a specified focal position. However, this restricts some practical applications of using such techniques in, for example, on-line measurements in high-value manufacturing and in-service inspections where multiple immersion measurements are not feasible to use. The main benefit of using ultrasonic phased arrays is that one array probe at one position can focus ultrasound beams at multiple points using different focal laws either physically or in data postprocessing. Potentially this means that accurate grain size measurements can be obtained from a single array measurement. In this paper, the classic backscattering method for conventional transducers is adapted to be used for full matrix capture datasets from an ultrasonic array. Three-dimensional ultrasonic models are developed in the proposed inverse process to measure material microstructure grain size. Experimental validations were performed on two metallic materials: copper (EN1652) and bright mild steel (BS970). A good agreement is shown between the experimentally measured grain sizes from array data and metallography measurements. Compared to the classic pulse-echo immersion back-scattering measurements, the proposed method enables accurate measurement of grain size in a direct contact configuration at fewer locations. This has potential to make on-line grain size measurements possible.

Optical nonlinear properties of a new polyamide from crystal violet terephthalate

In this study, the nonlinear optical properties of a new polymer poly crystal violet terephthalate (PCVT) as a solution and a thin film with different concentrations of 0.2, 0.6, and 1 mM and input power were investigated by using Z-scan technique at 532 nm CW laser beam wavelength. The negative nonlinear refractive index n 2 as well as reverse saturable and saturable absorption β of the solution and film PCVT samples were determined. Figures of merit were also determined. In comparison with the Z-scan results, a self-diffraction pattern setup was used to measure nonlinear refractive index. Results showed a significant laser power dependence of the number of far-field diffraction rings with power and concentration, consistent with the Z-scan data. The PCVT sample exhibited good optical limiting behavior. Hence, PCVT has important nonlinear properties, and its figures of merit can be optimized by adjusting the PCVT concentration and input power. PCVT is a promising candidate for the design of optical photonic switching and optical limiter devices.

Microstructure characterization and formability assessment of electron beam welded Nb-10Hf-1Ti (wt.%) refractory alloy sheets

Formability study on welded blanks of Nb-based refractory alloy C-103 (Nb-10Hf-1Ti (wt.%)) has tremendous potential for utilizing smaller sheets for realization of large-size divergent portions of upper-stage liquid engine nozzle of satellite launch vehicles and thrusters of attitude orbital control systems. In this work, vacuum-annealed monolithic C-103 sheets were electron beam welded successfully to obtain defect-free welds and detailed microstructural and mechanical characterizations were investigated. Columnar epitaxial grains were found in fusion zone (FZ) instead of equiaxed grains in base metal (BM). Detailed SEM and HRTEM analyses revealed spherical shape of nano-sized HfO2 precipitates with monoclinic crystal structure in the C-103 sheet. Further, microhardness across the weld cross-section indicated that the FZ had a uniform and maximum hardness of ∼195 HV0.5 due to formation of finer nano-sized HfO2 precipitates with higher number density, followed by a lowering of hardness in a narrow heat-affected zone. A marginal reduction in tensile strength of ∼6% with a considerable decrease in ductility of ∼29% was noticed for the welded sample. However, fracture occurred in the BM region, indicating good weld integrity. Furthermore, formability of the welded blanks was evaluated in terms of limiting dome height (LDH), forming limit diagram, and deep drawn cup depth. The effect of the presence of WZ on the formability of the C-103 sheet was estimated under uniaxial, plane strain, and biaxial tensile strain paths for the first time, and the results were compared with the monolithic sample. It was noted that the failure limit of the welded specimens decreased compared to that of the monolithic sample, resulting in a lower LDH of approximately 69% and 62% when deformed along plane strain and biaxial tensile strain paths, respectively. However, a marginal variation in LDH was observed for the uniaxial strain path. Also, the welded blank had more resistance to material flow into the die cavity due to the harder weld region, resulting in a reduction of deep drawn cup depth by 52% than that of the monolithic blank. The overall results concluded that the presence of the WZ significantly affected the formability of the C-103 sheet, especially in plane strain and biaxial strain paths. However, the fracture was never found to be propagating along the weld line, indicating the ability of the weld to sustain large plastic strains. This study provides insightful information on the formability of electron beam welded C-103 sheets for the successful fabrication of space components.

Photoluminescent Lanthanide(III) Complexes Based on 2-[((4-Chlorophenyl)amino)methylene]-5,5-dimethylcyclohexane-1,3-dione

Five coordination compounds of the general formula [LnL2(NO3)3]n (Ln3+ = Eu (I), Sm (II), Tb(III), Dy (IV), and Gd (V)) are synthesized from 2-[((4-chlorophenyl)amino)methylene]-5,5-dimethylcyclohexane-1,3-dione (L). The crystal structures of the ligand and complex III are determined by X-ray diffraction (XRD) of single crystals (CIF files CCDC nos. 2298715 (L) and 2298716 (III)). Complex III is polymeric due to the bidentate-bridging coordination of the ligand by the oxygen atoms of the cyclohexanedione fragment, and the coordination number of the central atom is ten. According to the phase XRD data, all synthesized polycrystalline compounds are isostructural to the single crystals of complex III. The photoluminescence properties of the ligand and coordination compounds in the polycrystalline state are studied. The energy transfer from the ligand to lanthanide(III) ion is shown to proceed via the “antenna” mechanism in the case of the europium(III), samarium(III), and terbium(III) compounds. Among the series of the complexes, the highest quantum yield is observed for compound I (21.9%), and the sensibilization efficiency of the europium(III) complex is 43.5%.

Deep operator network surrogate for phase-field modeling of metal grain growth during solidification

A deep operator network (DeepONet) has been constructed that generates accurate representations of phase-field model simulations for evolving two dimensional metal grain morphology growing from melt. These representations serve as lower resolution, computationally efficient stand-ins for quick parameter space exploration of solutions to the Allen–Cahn equations that dictate the phase-field model simulations. The experimental target for the phase-field model is a uranium casting system cooling a 434 g uranium charge from a maximum temperature of 1400 °C at an average rate of 30 °Cmin, traversing the crystallographic phases of the pure metal. Experimental parameters inform the phase-field model, whose higher resolution computational model solutions are used to train the DeepONet in a given parameter space with the aim of developing a faster, more efficient method for predicting the solidifying metal’s microstructure at different potential experimental values. The final DeepONet generates high accuracy, lower resolution predictions with cumulative relative approximation error over all timesteps of less than 0.5%, while ensuring solutions remain within physically feasible ranges. These relative error values are comparable with other state-of-the-art DeepONet models for microstructure evolution, while significantly reducing the amount of training data required. Training a convolutional neural network simultaneously with the DeepONet, enforcing realistic values at the complex metal grain boundaries, and mathematically encoding boundary conditions into the structure of the DeepONet improved prediction accuracy and computational efficiency over a standard DeepONet model.