Fine-grained Structure Research Articles

SDGIN: Structure-aware dual-level graph interactive network with semantic roles for visual dialog

Visual Dialog aims to answer an appropriate response based on a multi-round dialog history and a given image. Existing methods either focus on semantic interaction, or implicitly capture coarse-grained structural interaction (e.g., pronoun co-references). The fine-grained and explicit structural interaction feature for dialog history is seldom explored, resulting in insufficient feature learning and difficulty in capturing precise context. To address these issues, we propose a structure-aware dual-level graph interactive network (SDGIN) that integrates verb-specific semantic roles and co-reference resolution to explicitly capture context structural features for discriminative and generative tasks in visual dialog. Specifically, we create a novel structural interaction graph that injects syntactic knowledge priors into dialog by introducing semantic role labeling that imply which words are sentence stems. Furthermore, considering the single perspective limitation of previous algorithms, we design a dual-perspective mechanism that learns fine-grained token-level context structure features and coarse-grained utterance-level interactions in parallel. It possess an elegant view to explore precise context interactions, realizing the mutual complementation and enhancement of different granularity features. Experimental results show the superiority of our proposed approach. Compared to other task-specific models, our SDGIN outperforms previous models and achieves a significant improvement on the benchmark dataset VisDial v1.0.

Структурно-фазові характеристики та механічні властивості TWIP-сталі Fe-24Mn-11Al-1,4C

TWIP steels belong to a number of modern innovative structural materials that combine a high level of mechanical characteristics and low density, which brings their specific strength closer to the level of titanium alloys. Such steels usually do not contain deficient components and they are suitable for wide commercial industrial production. The most high-strength alloys include around 20-30 % Mn (wt.), around 10 % (wt.) Al and 1% (wt.) C. Such chemical composition brings them closer to the three-phase region, in which austenite, ferrite and k-carbides can simultaneously exist. According to this, it is possible to change mechanical characteristics of such alloys in a wide range only by heat treatment. Although in practice the best results are shown by a combination of deformation and heat treatment. The Manuscript presents a study of changes in the structural and phase characteristics and mechanical properties of the Fe-24Mn-11Al-1,4C alloy, prepared by electroslag melting, in its initial state, after deformation and annealing, and after deformation with subsequent hardening and aging. A fractographic analysis of the studied samples destruction places was also carried out. It is shown that the original sample obtained by electroslag remelting has the highest plasticity and the lowest strength, which is explained by combination of largest alloying of austenite and as-cast microstructure. The deformed and annealed sample is characterized by a pronounced fine-grained structure in which carbides are separated along the grain boundaries. Such a sample exhibits a strength greater than 1.1 GPa and the lowest ductility of 4.26 %. The deformed sample after quenching and aging has a similar structure, but the carbide inclusions are much finer, and the alloying rate of austenite is higher than the previous one. Such a sample shows the highest strength of more than 1.2 GPa and plasticity of 8.6 %. Keywords: TWIP-steels, casting, deformation and heat treatment, structural and phase characteristics, fractography, mechanical properties.

Experimental studies of the bearing capacity of pipe steels of sewage systems

It was established that the value of the critical stress SK for all experimental steels increases with the increase in the service life, and the impact viscosity decreases, which indicates structural embrittlement of pipe steels associated with their sudden flooding. It is shown that the new 20FA steel has the highest visco-plastic properties and resistance to brittle fracture, which is economically modified with a carbide-forming element (vanadium) and has a fine-grained structure and a low content of harmful impurities (sulfur, phosphorus). The microstrain of the α-Fe crystal lattice, as well as the quantitative decay of cementite and the redistribution of carbon between ferrite and pearlite, were evaluated by X-ray diffraction methods. The new steel grade 10FA is recommended for use in the construction of underground sewage systems and, for example, bridge structures, which are constantly under cyclic loads with simultaneous contact with a corrosive and aggressive environment. For the first time, the influence of the service life of pipelines on the hydrogen content and microcracks in pipe steels was determined.

Microstructure Evolution and Constitutive Modelling of Deformation Behavior for Al-Mg-Si-Cu-Sc-Zr Alloy Processed with Isothermal Multidirectional Forging

This research is devoted to the microstructure evolution and deformation behavior of the Al-1.2Mg-0.7Si-1.0Cu-0.1Sc-0.2Zr alloy during the isothermal multidirectional forging (MDF) in a large cumulative strain and temperature range. The structure investigation of the studied alloy revealed several phases precipitated during solidification, among which θ(Al2Cu), Q(Al5Cu2Mg8Si6), Mg2Si, Sc-bearing W(AlScCu) and V(AlSi2Sc2) phases were observed. The MDF at 150–350 °C and a maximum cumulative strain of 14.4 significantly refined grain structure providing a mean grain size of 1.2–2.1 µm. The L12 structured Al3(Sc,Zr) dispersoids with a mean size of 10 ± 1 nm were formed during two-step homogenization annealing. Due to Zener pinning of the nanoscale dispersoids and fine-grained structure, the alloy exhibited near-superplastic behavior in a temperature range of 460–500 °C and strain rate range of 2 × 10−3–1 × 10−2 s−1 with the maximum elongation to failure of ~300%. After a strengthening heat treatment, the forged alloy exhibited the yield strength of 326 ± 5 MPa, ultimate tensile strength of 366 ± 5 MPa, and elongation of 10 ± 3%. The hot deformation behavior was described using the Arrhenius type model. The developed model demonstrated high predictability accuracy with a maximum average absolute relative error of 6.6%.

Using the Radial Shear Rolling Method for Fast and Deep Processing Technology of a Steel Ingot Cast Structure.

In advancing special materials, seamless integration into existing production chains is paramount. Beyond creating improved alloy compositions, precision in processing methods is crucial to preserve desired properties without drawbacks. The synergy between alloy formulation and processing techniques is pivotal for maximizing the benefits of innovative materials. By focusing on advanced deep processing technology for small ingots of modified 12% Cr stainless steel, this paper delves into the transformation of cast ingot steel structures using radial shear rolling (RSR) processing. Through a series of nine passes, rolling ingots from a 32 mm to a 13 mm diameter with a total elongation factor of 6.02, a notable shift occurred. This single-operation process effectuated a substantial change in sample structure, transitioning from a coarse-grained cast structure (0.5-1.5 mm) to an equiaxed fine-grained structure with peripheral grain sizes of 1-4 μm and an elongated rolling texture in the axial part of the bar. The complete transformation of the initial cast dendritic structure validates the implementation of the RSR method for the deep processing of ingots.

A comprehensive structural and electrochemical study on the performance of Mn-phosphate layers

Several manganese phosphating routes, including the influence of immersion time (15 min. and 30 min.), addition of accelerators (Ni(NO3)2, 2 g/l), modification in the activation stage (increased concentration in the activator), and ultrasonic stirring, were used to obtain films with a variety of characteristics. This research uses the following common analytical methods for the phosphate characterisation: scanning electron microscopy (SEM) and electrochemical techniques (potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS). Thus, modifications in the coating mass, covering efficiency, surface appearance, and chemical composition/structure could be determined. This study showed that accelerators induced the formation of thicker layers (up to 125 % bigger), whereas ultrasonic stirring assisted with reducing the crystal sizes and developing denser films (up to 50 % reduction in the icorr values). The dry frictional tests showed that the wear behaviour depended on the phosphate thickness, crystal density, and film tortuosity. A fine-grained structure or a thick film contributed to an improved wear performance (near 80 % reduction in the coefficient of friction), but grains that are too fine along with an intricate structure worsened the behaviour under frictional forces.

Physiological sensor data cleaning with autoencoders

Objective. Physiological sensor data (e.g. photoplethysmograph) is important for remotely monitoring patients’ vital signals, but is often affected by measurement noise. Existing feature-based models for signal cleaning can be limited as they might not capture the full signal characteristics. Approach. In this work we present a deep learning framework for sensor signal cleaning based on dilated convolutions which capture the coarse- and fine-grained structure in order to classify whether a signal is noisy or clean. However, since obtaining annotated physiological data is costly and time-consuming we propose an autoencoder-based semi-supervised model which is able to learn a representation of the sensor signal characteristics, also adding an element of interpretability. Main results. Our proposed models are over 8% more accurate than existing feature-based approaches with half the false positive/negative rates. Finally, we show that with careful tuning (that can be improved further), the semi-supervised model outperforms supervised approaches suggesting that incorporating the large amounts of available unlabeled data can be advantageous for achieving high accuracy (over 90%) and minimizing the false positive/negative rates. Significance. Our approach enables us to reliably separate clean from noisy physiological sensor signal that can pave the development of reliable features and eventually support decisions regarding drug efficacy in clinical trials.

Investigation of joints from corrosion-resistant steels obtained by energy-saving rotary friction welding technology

In this article the possibility of application of rotary friction welding for joining parts from stainless steels is evaluated on the example of 10Cr17Ni13Mo2Ti steel. Application of rotary friction welding allows to refuse post-weld heat treatment, which is labor-intensive, energy-consuming and environmentally harmful operation. For this purpose, cylindrical samples of 20 mm in diameter were made from the above steel using friction welding without subsequent heat treatment. The microstructure, microhardness measurement, tensile and impact bending tests were carried out. The microstructure study showed that the weld width across the entire cross-section does not exceed 12 μm. It has an irregular wavy shape with a fine-grained structure. Tensile tests showed that the average value of yield strength of samples with welded joint is 1.6% higher than the same value of samples from the base metal, but the average value of time resistance is lower by 5.6%. Impact bending test results showed that the average impact toughness of welded samples is almost the same as that of base metal samples. According to the results of studies concluded that the weldability of steel 10Cr17Ni13Mo2Ti using friction welding is good, welded joints are obtained high quality.

PATHOMORPHOLOGICAL CHANGES IN THE ORGANS OF CATS CAUSED BY ALIMENTARY LYMPHOMA. CLINICAL CASES

The article presents the results of clinical, ultrasonographic, pathomorphological and immunohistochemical studies of two random cases of alimentary lymphoma in 9- and 12-year-old domestic cats. Clinical signs of the disease were similar and characterized by anorexia, cachexia, vomiting and diarrhea that appeared in different periods of the disease. The mucous membranes of the oral cavity and eyes were icteric, the abdomen was visually enlarged, palpation revealed nodular thickenings in the abdominal cavity. During the ultrasound diagnostics, diffuse multiple non-encapsulated anechoic formations with uneven edges and growth of tumorous tissue into the intestinal wall were visualized. In another cat, there was an encapsulated formation of a hypoechoic fine-grained structure with well-defined vascularization.
 From the moment of the preliminary diagnosis until the very death, the cats were kept in the clinic under supervision. After the death, an autopsy was performed with the selection of material for histopathological examination. Organs’ fragments were fixed in 10% aqueous solution of neutral formalin and Carnois fluid. Histological preparations were made according to the generally accepted methods. Immunophenotyping of lymphoma type was performed using CD3 (T-cell) and CD79a (B-cell) markers. During the pathological autopsy, an increase in mesenteric lymph nodes, their compaction, and focal thickening of the small intestine wall were revealed. The histological examination showed that jejunum was the most infiltrated intestinal segment, in which massive, diffusely placed monomorphic lymphoblastic cells were localized in the mucous membrane lamina, submucosa and muscle layers. The submucosal layer vessels were sharply dilated, filled with erythrocytes; the muscles of the inner circular layer were swollen. The outer (longitudinal) muscle layer of the jejunum thickened significantly and was intensively infiltrated by lymphoblastic cells.
 Typical diffuse lymphoblastic proliferations were also detected in the cortical substance of lymph nodes and lymphoid nodules. Stasis and significant expansion of the marginal sinus vessels were visualized too. In addition, moderate mononuclear lymphoblastic infiltrates were detected in the pancreas parenchyma with their perivascular location. Immunohistochemically, a significant positive expression of CD3 cells was detected both in the jejunum mucous membrane and the marginal sinus area, around the germinal centers of the lymph nodes, which indicated a T-cell type of lymphoma.

Effect of Mo content on the microstructure and mechanical properties of CoCrFeNiMox HEA coatings deposited by high power impulse magnetron sputtering

In this work, CoCrFeNiMox high entropy alloy (HEA) films were deposited by High Power Impulse Magnetron Sputtering (HiPIMS) using pure Mo and equiatomic CoCrFeNi targets. The effect of Mo content on the microstructure, residual stress state, and mechanical properties of the films was investigated in the range of 0–20 at.%. All films exhibited a columnar growth morphology and a high density of planar defects. Increasing the Mo content promoted the formation of a fine-grained structure and induced the transformation from a single face-centered cubic (FCC) phase to a mixture of FCC and body-centered cubic (BCC) phases. All produced films displayed a compressive residual stress state regardless of the Mo concentration. In terms of mechanical properties, the hardness of the films increased with increasing Mo content due to solid solution and grain boundary strengthening, along with the formation of a hard BCC phase. On the other hand, the elastic modulus decreased, likely due to the formation of an amorphous phase at higher Mo concentrations.

StAA: adversarial graph autoencoder for spatial clustering task of spatially resolved transcriptomics.

With the development of spatially resolved transcriptomics technologies, it is now possible to explore the gene expression profiles of single cells while preserving their spatial context. Spatial clustering plays a key role in spatial transcriptome data analysis. In the past 2 years, several graph neural network-based methods have emerged, which significantly improved the accuracy of spatial clustering. However, accurately identifying the boundaries of spatial domains remains a challenging task. In this article, we propose stAA, an adversarial variational graph autoencoder, to identify spatial domain. stAA generates cell embedding by leveraging gene expression and spatial information using graph neural networks and enforces the distribution of cell embeddings to a prior distribution through Wasserstein distance. The adversarial training process can make cell embeddings better capture spatial domain information and more robust. Moreover, stAA incorporates global graph information into cell embeddings using labels generated by pre-clustering. Our experimental results show that stAA outperforms the state-of-the-art methods and achieves better clustering results across different profiling platforms and various resolutions. We also conducted numerous biological analyses and found that stAA can identify fine-grained structures in tissues, recognize different functional subtypes within tumors and accurately identify developmental trajectories.

INVESTIGATION OF MICROSTRUCTURE OF AA7075 ALLOYS AFTER SEVERE PLASTIC DEFORMATION APPLICATION

The aim of this study is to investigate the change of microstructural properties of AA7075 alloys after severe plastic deformation. Severe Plastic Deformation is a process used to improve the properties of the material by creating intense plastic deformations on the material surface. Equal channel angular compression molding (ECAP) was used for the severe plastic deformation process in our study. AA7075 alloy samples were primarily prepared for severe plastic deformation treatment. Then, the microstructural properties of the samples were investigated using various imaging techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The research results showed that significant microstructural changes occurred in AA7075 alloys after the severe plastic deformation process. The SPD process improved the mechanical properties of the material by transforming the crystalline structures of the material into a fine-grained structure. In addition, it was observed that deformation lines and pits occurred on the surface of the samples after the SPD process. It is seen that the SPD treatment increases the mechanical properties of the material such as strength, hardness and durability. Therefore, this study is an important step towards the development of the alloy's use in various industries.

Study on the mechanism of mechanical properties deterioration of brake disc materials of high-speed train

The mechanical properties of high-speed train brake disc will deteriorate after service, it is necessary to study the degradation mechanism in order to better understand the service process of the material. In this study, the microstructure evolution of the material in the hot spot area of the brake disc was observed by microstructure analysis, and a mixed structure of coarse and fine grains was formed. Through DIC tensile test and in-situ tensile test, the mechanism of mechanical property degradation of brake disc was obtained. The fine grain zone in the hot spot area forms a constraint effect on the coarse grain zone, resulting in uncoordinated deformation. It further causes strain localization and micro-cracks, resulting in a decrease in the bearing capacity and strength of the material. According to EBSD analysis, it is found that the distribution difference of grain boundary orientation further increases the degree of uncoordinated deformation between coarse and fine grains, resulting in stress concentration at the junction and inducing the formation of microcracks. The research results provide guidance for crack damage identification of brake disc. It is suggested that attention should be paid to the change of microstructure during the condition-based maintenance of brake disc, which is of great significance to ensure the safe operation of high-speed trains.

Mitigating Stress Corrosion Cracking of 304L and 316L Laser Welds in a Salt Spray through Micro-Shot Peening

Two austenitic stainless steel (ASS) plates, 304L and 316L, were cold-rolled (304R and 316R) with a 10% reduction in thickness and then subjected to laser welding. Cold rolling caused slight surface hardening and introduced residual tensile stress into the ASS plates. The susceptibility to stress corrosion cracking (SCC) of the welds (304RW and 316RW) was determined using the U-bend test pieces in a salt spray. To highlight the stress concentration at the weld’s fusion boundary (FB), the top weld reinforcement was not ground off before bending. Moreover, micro-shot peening (MSP) was performed to mitigate the SCC of the welds by imposing high residual compressive stress and forming a fine-grained structure. Cold rolling increased the susceptibility of the 304R specimen to pitting corrosion and intergranular (IG) microcracking. Moreover, pitting corrosion and SCC were found more often at the FBs of the 304RW. The corrosion pits of the peened 304RW (304RWSP) were finer but greater in amount than the those of the un-peened one. The results also indicated that the 316L ASS welds with MSP were resistant to the incidence of pitting corrosion and SCC in a salt spray. The better reliability and longer service life of dry storage canisters could be achieved by using 316L ASS for the construction and application of MSP on it.

Effect of forging temperature on the microstructure, subsequent aging precipitation behavior, and mechanical properties of Mg-Gd-Y-Zr-Ag alloy

The deformation mechanism, microstructure evolution, and precipitation behavior of a Mg-8.9Gd-1.8Y-0.5Zr-0.2Ag (wt.%) alloy multi-directionally forged at three different temperatures were investigated. As the forging temperature increases, the particle-stimulated nucleation (PSN) effect diminishes as the number of dynamic precipitates decreases, pyramidal slip is activated, grain boundary migration accelerates, and continuous dynamic recrystallization (CDRX) dominates. The microstructures varied greatly, although fine-grained structures were formed at all different forging temperatures. Competitive precipitation between dynamic precipitate growth, dislocation-induced precipitation, and homogeneous precipitation was observed after aging treatment. Among them, the medium temperature (748 K) forged and aged alloy exhibits the best mechanical performance, with an ultimate tensile strength of 436 MPa, and elongation of 16.3%. The calculation indicates that the mixed precipitation structure containing the β′ precipitate band provides a 35% higher strengthening contribution than the typical homogeneously distributed precipitates. The formation of precipitation-free zones (PFZs) ensures that aging will not cause a dramatic decrease in ductility, which provides a reference for the industrial preparation of high-performance wrought Mg-Gd series alloys.

Severe Plastic Deformation of Mg–Zn–Zr–Ce Alloys: Advancing Corrosion Resistance and Mechanical Strength for Medical Applications

Magnesium-based alloys hold potential for medical applications, but face challenges like rapid bioresorption and limited mechanical strength during early bone healing. In our study, we present a novel Mg–Zn–Zr–Ce alloy with low cerium content (up to 0.1 wt.% Ce) processed using two severe plastic deformation (SPD) techniques. Through an innovative combination of multiaxial forging and multipass rolling, we have achieved a fine-grained structure with an average grain size of the primary α-Mg phase of 1.0 μm. This refined microstructure exhibits improved mechanical properties, including a substantial increase in yield strength (σYS) from 130 to 240 MPa, while preserving ductility. The alloy’s composition includes α-Mg grains, cerium and zinc hydrides, and intermetallic phases with cerium and zinc elements. Tensile testing of the fine-grained alloy demonstrates an enhancement in yield strength (σYS) to 250 MPa, marking a 2.8-fold improvement over the conventional state (σYS = 90 MPa), with a modest 2-fold reduction in ductility. Crucially, electrochemical tests conducted in physiological solutions highlight substantial advancements in corrosion resistance. The corrosion current was reduced from 14 to 2 μA/cm2, while polarization resistance decreased from 3.1 to 8.1 kΩ∙cm2, underlining the alloy’s enhanced resistance to biodegradation. Our results show that the novel Mg–Zn–Zr–Ce alloy, after combined SPD, demonstrates mitigated bioresorption and enhanced mechanical properties. Our findings highlight the fact that the introduction of this innovative alloy and the application of SPD represent significant steps towards addressing the limitations of magnesium-based alloys for medical implants, offering potential improvements in safety and effectiveness.

The effect of subgrain mobility on recrystallization kinetics: phase-field simulation study

The influence of grain boundary mobility on the recrystallization process (ReX) was investigated in this study using the phase-field approach. In accordance with the Read-Shockley equation, for the interfacial mobility as a function of the misorientation angle, the resulting microstructural evolution was studied. It was observed that the disappearance of low-angle grain boundaries (LAGBs) during the ReX process caused high-angle grain boundaries to move faster during the subsequent ReX stages. For materials with high stacking energy, such as aluminum, LAGBs were additionally found to play a significant role in the ReX process. The kinetics of the ReX process, coupled with grain growth, showed the typical behavior observed in fine-grained structures of pure aluminum.

Modeling Xylem Functionality Aspects.

Depending on the questions to be answered, water flow in the xylem can be modelled following different approaches with varying spatial and temporal resolution. When focussing on the influence of hydraulic architecture upon flow dynamics, distribution of water potentials in a tree crown or questions of vulnerability of the hydraulic system, functional-structural plant models, which link representations of morphological structure with simulated processes and with a virtual environment, can be a promising tool. Such a model will then include a network of idealized xylem segments, each representing the conducting part of a stem or branch segment, and a numerical machinery suitable for solving a system of differential equations on it reflecting the hydrodynamic laws, which are the basis of the broadly accepted cohesion-tension theory of water flow in plants. We will discuss functional-structural plant models, the simplifications that are useful for hydraulic simulations within this framework, the deduction of the used differential equations from basic physical conservation laws, and their numerical solution, as well as additional necessary models of radiation, photosynthesis, and stomatal conductance. In some supplementary notes, we are shortly addressing some related questions, for example, about root systems or about the relation between macro-scale hydraulic parameters and fine-grained (anatomical) xylem structure.

Influence of the powders phase composition and sintering atmosphere on the structure and magnetic properties of Mn-Zn ferrites

The magnetic properties of Mn-Zn ferrites depend strongly on the microstructure, chemical and phase composition. In this paper the effect of synthesis and sintering conditions on the structure, phase composition and properties of Mn-Zn ferrites is investigated. The specimens for the study were obtained by pressureless sintering. The magnetic properties were measured on a B-H analyzer. The structure was investigated by XRD and SEM. Materials with an average grain size of 2.2 μm were obtained by sintering at a temperature of 1265 °C. It was found that an increase in the synthesis temperature from 700 to 1000 °C promotes the growth of the initial magnetic permeability of these materials from 1100 to 1370. The rapid cooling of the powders synthesized at 1000 °C allows maintaining a high content of the spinel phase. In the structure of materials obtained by sintering powders with initially high spinel content at 1300 °C, grains of abnormally large size are formed. This leads to an increase in the initial permeability, magnetic induction at Hm = 1200 A/m, f = 10 kHz and magnetic losses at high frequencies (up to 500 kHz). A material with fine-grained structure was obtained by using air at the heating stage of pressureless sintering. This contributed to the reduction of magnetic losses without a significant decrease in Bm.

Realizing high energy density and discharge energy density in high hardness Ba1.938Bi0.375Nb5O15-based glass ceramics

The practical utility of glass-ceramics-based (GCs) energy storage materials is limited due to their low energy density. In this work, we synthesized the unleaded GCs containing two crystalline phases: Ba1.938Bi0.375Nb5O15 and BaNb2O6. An increase in crystallization time at a specific temperature initially leads to a decrease and then an increase in the dielectric permittivity (εr) and breakdown strength (BDS) due to changes in crystallinity. Specifically, at a crystallization temperature of 750 °C for 4 h, the BDS reaches approximately 1422 kV/cm, driven by a lower oxygen density, higher activation energy, and the formation of a fine-grained structure in the compact GCs. Numerical simulation was employed to uncover the underlying mechanism behind the enhanced BDS achieved through changing crystallization time. As a result of the enhanced BDS and polarization, this study achieved remarkable and comprehensive outcomes: a high efficiency (η) of 85.89%, a high energy density (Wrec) of 3.79 J/cm3, an ultrahigh discharge energy density (Wdis) of 3.26 J/cm3 and a high Vickers hardness (Hv) of 6.85 GPa. Meanwhile, this sample crystallized for 4 h demonstrates excellent thermal stability and frequency stability. These results show that these GCs could be highly competitive as lead-free materials for energy storage capacitors.