Materials

18 pages, 997 KB

Open AccessArticle

Selection of Base Materials for Repair Welding Using BWM-TOPSIS and BWM-RADAR Approaches

by Dušan Arsić, Djordje Ivković, Ranka Sudžum, Dragan Marinković and Nikola Komatina

Materials 2025, 18(24), 5696; https://doi.org/10.3390/ma18245696 - 18 Dec 2025

Viewed by 537

In this paper, the selection of the optimal base material to be used in the repair welding process is presented. The aim of the study was to determine which of the available materials has the best characteristics, based on an analysis conducted in [...] Read more.

In this paper, the selection of the optimal base material to be used in the repair welding process is presented. The aim of the study was to determine which of the available materials has the best characteristics, based on an analysis conducted in a company engaged in construction works. Three base materials were considered in the study: ABRADUR 58, E DUR 600, and CrWC 600 electrodes. Repair welding was performed on components for a construction machinery facility using the manual metal arc welding procedure. For the selection of the optimal base material, a combined Multi-Attribute Decision-Making (MADM) approach was applied. The base materials were evaluated based on four attributes: wear track width, cost, mass loss, and hardness of welded layers. The Best–Worst Method (BWM) was used to determine the attribute weights, while the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Ranking based on the Distances And Range (RADAR) methods were applied in parallel for the ranking and selection of base materials. The analysis showed that in the considered case, the E DUR 600 electrode was the most suitable choice, which was confirmed through the application of both the TOPSIS and RADAR methods. Full article

(This article belongs to the Special Issue Advanced Materials for Sustainable Industry 5.0)

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21 pages, 9201 KB

Open AccessArticle

Study on the Complex Band Structure and Auxetic Behavior of Fractal Re-Entrant Honeycomb Metamaterials

by Jingru Li, Siyu Chen, Wei Lin and Yuzhang Lin

Materials 2025, 18(24), 5695; https://doi.org/10.3390/ma18245695 - 18 Dec 2025

Cited by 1 | Viewed by 817

Abstract

In order to break the limitation of metamaterials used in the vibration and sound reduction field, this work designed a two-dimensional metamaterial based on the re-entrant honeycomb lattice and using the fractal technique. The first, second, and third-order fractal re-entrant honeycomb metamaterials are [...] Read more.

In order to break the limitation of metamaterials used in the vibration and sound reduction field, this work designed a two-dimensional metamaterial based on the re-entrant honeycomb lattice and using the fractal technique. The first, second, and third-order fractal re-entrant honeycomb metamaterials are analyzed, respectively, within the established numerical models responsible for predicting the effective Poisson’s ratio, the real band structure, and the attenuation diagram. The effects of the fractal order, fractal ratio, and geometrical characteristics on these multiple functionalities are investigated simultaneously. Through adjusting the proposed fractal metamaterials, the results show that the transformation of auxetic performance, the number and location of multiple stop bands, the attenuation level inside the stop bands, and the wave decaying directionality can be flexibly tuned. This demonstrates that the compatibility of mechanical features and wave motion characteristics is successfully achieved in the present work. It provides a theoretical and technical basis for the development of multi-functional design methods of metamaterials in solving engineering problems. Full article

(This article belongs to the Special Issue Advanced Materials in Acoustics and Vibration)

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30 pages, 10659 KB

Open AccessArticle

Performance Analysis of Artificial Neural Network and Its Optimized Models on Compressive Strength Prediction of Recycled Cement Mortar

by Lin-Bin Li, Guang-Ji Yin, Jing-Jing Shao, Ling Miao, Yu-Jie Lang, Jia-Jia Zhu and Shan-Shan Cheng

Materials 2025, 18(24), 5694; https://doi.org/10.3390/ma18245694 - 18 Dec 2025

Cited by 1 | Viewed by 713

Abstract

In the background of sustainable development in the construction industry, recycled cement mortar (RCM) has emerged as a research hotspot due to its eco-friendly features, where mechanical properties serve as critical indicators for evaluating its engineering applicability. This study proposes an artificial neural [...] Read more.

In the background of sustainable development in the construction industry, recycled cement mortar (RCM) has emerged as a research hotspot due to its eco-friendly features, where mechanical properties serve as critical indicators for evaluating its engineering applicability. This study proposes an artificial neural network (ANN) model optimized by intelligent algorithms, including the GWO (grey wolf optimizer), PSO (particle swarm optimization), and a GA (genetic algorithm), to predict the compressive strength of recycled mortar. By integrating experimental and prediction data, we establish a comprehensive database with eight input variables, including the water–cement ratio (W/C), cement–sand ratio (C/S), fly ash content (FA), aggregate replacement rate (ARR), and curing age. The predictive performance of neural network models with different database sizes (database 1: experimental data of RCM; database 2: experimental data of RCM and ordinary mortar; database 3: model prediction data of RCM, experimental data of RCM, and ordinary mortar) is analyzed. The results show that the intelligent optimization algorithms significantly enhance the predictive performance of the ANN model. Among them, the PSO-ANN model demonstrates optimal performance, with R² = 0.92, MSE = 0.007, and MAE = 0.0632, followed by the GA-ANN model and the GWO-ANN model. SHAP analysis reveals that the W/C, C/S, and curing age are the key variables influencing the compression strength. Furthermore, the size of the dataset does not significantly influence the computation time for the above models but is primarily governed by the complexity of the optimization algorithms. This study provides an efficient data-driven method for the mix design of RCM and a theoretical support for its engineering applications. Full article

(This article belongs to the Special Issue Modeling and Analysis of Composite Materials and Structures in Civil Engineering (Second Edition))

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13 pages, 6633 KB

Open AccessArticle

Composite Oxidation Mechanism of Cu/Cu Contact Pairs During Current-Carrying Rolling in O₂-N₂-H₂O Vapor Mixture

by Jianhua Cheng, Fei Li, Yuhang Li, Haihong Wu, Bohan Li, Chenfei Song, Zhibin Fu and Yongzhen Zhang

Materials 2025, 18(24), 5693; https://doi.org/10.3390/ma18245693 - 18 Dec 2025

Cited by 1 | Viewed by 557

Abstract

Oxidation is a critical factor contributing to material wear and the degradation of conductive performance during current-carrying tribological processes. The present study investigated the composite oxidation mechanisms that occurred during current-carrying rolling in mixed atmospheres containing O₂ and H₂O vapor. [...] Read more.

Oxidation is a critical factor contributing to material wear and the degradation of conductive performance during current-carrying tribological processes. The present study investigated the composite oxidation mechanisms that occurred during current-carrying rolling in mixed atmospheres containing O₂ and H₂O vapor. The results obtained in a dry N₂/O₂ mixture, humid N₂, and humid N₂/O₂ mixture indicated that the oxidation mechanisms on current-carrying rolling surfaces involved thermal oxidation, tribo-oxidation, and anodic oxidation. XPS analysis confirmed that the primary oxidation product was CuO. Conductive atomic force microscopy (C-AFM) revealed that surface oxidation caused a significant reduction in conductive α-spots, leading to an increase in contact resistance. Contact resistance exhibited a quasi-linear relationship with the surface CuO content. Contact angle measurements and adhesion tests showed that the enhanced hydrophilicity of the oxidized surface and the resulting high adhesion contributed to an increase in the macroscopic friction coefficient. In humid N₂/O₂ with 50% relative humidity (RH), the friction coefficient rapidly exceeded 0.8 when the O₂ content surpassed 25%. Wear morphology analysis demonstrated that this abrupt increase in the friction coefficient induced fatigue wear on the surface. Overall, the present study elucidated the composite oxidation mechanisms during current-carrying rolling and clarified the pathways through which oxidation affected current-carrying tribological performance. These findings may contribute to improved failure analysis and the safe, reliable operation of electrical contact pairs. Full article

(This article belongs to the Section Materials Chemistry)

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14 pages, 1493 KB

Open AccessArticle

Toward Fully Bio-Based Polyurethane Foams: Effects of Radish Seed and Tall Oil Polyols on Biofoam Properties

by Mikelis Kirpluks, Maria Kurańska, Elżbieta Malewska, Łukasz Bonder, Nanija Dambe, Dominika Grucela and Stanisław Kuciel

Materials 2025, 18(24), 5692; https://doi.org/10.3390/ma18245692 - 18 Dec 2025

Cited by 1 | Viewed by 555

Abstract

The development of bio-based polyurethane foams has become a key direction in polymer materials research, driven by the need to replace petrochemical raw materials with renewable alternatives. This study investigates the synthesis and characterization of open-cell polyurethane foams produced using mixed bio-polyols derived [...] Read more.

The development of bio-based polyurethane foams has become a key direction in polymer materials research, driven by the need to replace petrochemical raw materials with renewable alternatives. This study investigates the synthesis and characterization of open-cell polyurethane foams produced using mixed bio-polyols derived from radish seed oil and tall oil in various mass ratios. For comparison, reference foams based on a radish seed oil polyol, tall oil-based polyol and a petrochemical polyol were also prepared. The influence of the polyol composition on the foaming behavior, cell structure, apparent density, mechanical properties, and thermal conductivity of the resulting foams was analyzed. Full article

(This article belongs to the Special Issue Study on the Processing, Forming and Properties of Polymer Microcellular Foams)

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17 pages, 4669 KB

Open AccessArticle

One-Step Electrodeposition of Hybrid Semiconductive CdSe/Nitrogen-Doped Carbon Dots Thin Films

by Katerina Pappa, Maria Myrto Dardavila, Athanasios Tzanis, Adamantia Zourou, Christina Mitzithra, Stylianos Hamilakis, Zaphirios Loizos, Konstantinos Kordatos and Constantina Kollia

Materials 2025, 18(24), 5691; https://doi.org/10.3390/ma18245691 - 18 Dec 2025

Viewed by 562

Abstract

Novel hybrid semiconducting thin films comprising CdSe with the addition of nitrogen-doped carbon dots (NCDs) were developed onto titanium substrates using a one-step electrocodeposition technique. The deposition took place using an acidic aqueous electrolytic bath containing hydrothermally produced ΝCDs under direct and pulse [...] Read more.

Novel hybrid semiconducting thin films comprising CdSe with the addition of nitrogen-doped carbon dots (NCDs) were developed onto titanium substrates using a one-step electrocodeposition technique. The deposition took place using an acidic aqueous electrolytic bath containing hydrothermally produced ΝCDs under direct and pulse current regime. The specimens were studied using XRD, SEM-EDS, and UV-Vis spectroscopy techniques to determine their microstructural characteristics, surface morphology and composition and the energy gap, respectively. Their photochemical behavior was studied utilizing a photoelectrochemical cell (PEC). Variations in physical properties, along with significantly improved photoelectrochemical responses, were observed for the NCD-infused semiconductive thin films compared to their plain CdSe counterparts. These variations were highly affected by the incorporation rate of the NCDs in each thin film, as well as the imposed electrolysis conditions. Full article

(This article belongs to the Special Issue Design and Electrochemical Synthesis of Multifunctional Surfaces)

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24 pages, 3258 KB

Open AccessReview

Progress in Charge Transfer in 2D Metal Halide Perovskite Heterojunctions: A Review

by Chenjing Quan, Jiahe Yan, Xiaofeng Liu, Qing Lin, Beibei Xu and Jianrong Qiu

Materials 2025, 18(24), 5690; https://doi.org/10.3390/ma18245690 - 18 Dec 2025

Cited by 1 | Viewed by 760

Abstract

Metal halide perovskite (MHP)-based heterojunctions have become a forefront area in the research of optoelectronic functional materials due to their unique layered crystal structure, tunable band gaps, and exceptional optoelectronic properties. Recent studies have demonstrated that interface charge transfer is a crucial factor [...] Read more.

Metal halide perovskite (MHP)-based heterojunctions have become a forefront area in the research of optoelectronic functional materials due to their unique layered crystal structure, tunable band gaps, and exceptional optoelectronic properties. Recent studies have demonstrated that interface charge transfer is a crucial factor in determining the optoelectronic performance of the heterojunction devices. By constructing heterojunctions between MHPs and two-dimensional (2D) materials such as graphene, MoS₂, and WS₂, efficient electron–hole separation and transport can be achieved, significantly extending carrier lifetimes and suppressing non-radiative recombination. This results in enhanced response speed and energy conversion efficiency in photodetectors, photovoltaic devices, and light-emitting devices (LEDs). In these heterojunctions, the thickness of the MHP layer, interface defect density, and band alignment significantly influence carrier dynamics. Furthermore, techniques such as interface engineering, molecular passivation, and band engineering can effectively optimize charge separation efficiency and improve device stability. The integration of multilayer heterojunctions and flexible designs also presents new opportunities for expanding the functionality of high-performance optoelectronic devices. In this review, we systematically summarize the charge transfer mechanisms in MHP-based heterojunctions and highlight recent advances in their optoelectronic applications. Particular emphasis is placed on the influence of interfacial coupling on carrier generation, transport, and recombination dynamics. Furthermore, the ultrafast dynamic behaviors and band-engineering strategies in representative heterojunctions are elaborated, together with key factors and approaches for enhancing charge transfer efficiency. Finally, the potential of MHP heterojunctions for high-performance optoelectronic devices and emerging photonic systems is discussed. This review aims to provide a comprehensive theoretical and experimental reference for future research and to offer new insights into the rational design and application of flexible optoelectronics, photovoltaics, light-emitting devices, and quantum photonic technologies. Full article

(This article belongs to the Section Energy Materials)

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30 pages, 13137 KB

Open AccessEditor’s ChoiceArticle

Effect of Ni Addition on the Solidification of Liquid Al and Solid Cu Diffusion Couples

by Vigneshwar Hari, Stuart D. McDonald, Xin Fu Tan and Kazuhiro Nogita

Materials 2025, 18(24), 5689; https://doi.org/10.3390/ma18245689 - 18 Dec 2025

Cited by 1 | Viewed by 790

Abstract

Al-Ni alloys have a unique set of properties including high conductivity, high fluidity, good thermal stability, and reasonable strength. These properties are also needed for effective braze fillers, a novel application for Al-Ni alloys. A Cu substrate was reacted with pure liquid Al, [...] Read more.

Al-Ni alloys have a unique set of properties including high conductivity, high fluidity, good thermal stability, and reasonable strength. These properties are also needed for effective braze fillers, a novel application for Al-Ni alloys. A Cu substrate was reacted with pure liquid Al, and the resulting microstructure upon solidification was observed and analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). This diffusion couple was compared with the diffusion couple between liquid eutectic Al-3at.%Ni and a Cu substrate. Several phases unique to the solidified liquid in the Al-Ni/Cu diffusion couple were observed, such as Al₇Cu₄Ni (τ), Al₃(Cu, Ni)₂, and Al₃Ni. These microstructures were compared with a mathematical model based on Fick’s second law, as well as calculation of phase diagram (CALPHAD) modelling. The approximate calculated concentration profile of Cu in the liquid phase was validated against the microstructural observations and proved effective to explain the observed microstructural features. Liquid Al-3at.%Ni was found to limit the growth of the brittle Al₂Cu (θ) phase during solidification by limiting Cu solubility in the liquid phase, which would be beneficial for use in dissimilar joints between Al and Cu. Full article

(This article belongs to the Section Metals and Alloys)

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21 pages, 9468 KB

Open AccessArticle

Influence of Nodal Spheres on the Mechanical Behaviour of Auxetic Materials Manufactured with PA12

by Ismael Lamas, Iria Feijoo, Silvia Gómez, Alejandro Pereira, José A. Pérez and M. Consuelo Pérez

Materials 2025, 18(24), 5688; https://doi.org/10.3390/ma18245688 - 18 Dec 2025

Cited by 1 | Viewed by 658

Abstract

Auxetic metamaterials, characterised by a negative Poisson’s ratio, offer excellent energy absorption but often present limited compressive strength due to their strut-based architectures. Selective laser sintering (SLS) enables the precise fabrication of these structures, yet enhancing their mechanical performance remains challenging. This research [...] Read more.

Auxetic metamaterials, characterised by a negative Poisson’s ratio, offer excellent energy absorption but often present limited compressive strength due to their strut-based architectures. Selective laser sintering (SLS) enables the precise fabrication of these structures, yet enhancing their mechanical performance remains challenging. This research investigates the influence of nodal spheres on re-entrant dodecahedral unit cells produced in PA12, varying node-to-strut diameter ratios (1:1, 2:1, and 3:1). Compression tests reveal significant increases in stiffness and compressive strength, reaching up to 88.70% for the 3:1 ratio. When normalised by relative density, the 2:1 configuration proves most effective, achieving a 35.33% increase in specific strength and a 19.58% improvement in specific energy absorption. The deformation behaviour indicates a mixed bending–stretching mechanism, with geometry exerting a stronger influence than the base material. Although larger nodal spheres enhance absolute strength, they also increase mass and relative density, which may limit their suitability for weight-sensitive applications. Overall, these findings highlight nodal reinforcement as a promising strategy to enhance the mechanical efficiency of auxetic metamaterials while maintaining their auxetic response. These improvements support applications in aerospace, automotive engineering, personal protection systems, lightweight structural panels, and energy-absorbing components. Full article

(This article belongs to the Special Issue Advanced Materials and Processing Technologies)

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20 pages, 11502 KB

Open AccessArticle

Laser Remelting of Biocompatible Ti-Based Glass-Forming Alloys: Microstructure, Mechanical Properties, and Cytotoxicity

by Aleksandra Małachowska, Wiktoria Drej, Agnieszka Rusak, Tomasz Kozieł, Denis Pikulski and Wojciech Stopyra

Materials 2025, 18(24), 5687; https://doi.org/10.3390/ma18245687 - 18 Dec 2025

Cited by 1 | Viewed by 766

Abstract

Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti₄₂Zr₃₅Si [...] Read more.

Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃, Ti₄₂Zr₄₀Ta₃Si₁₅, Ti₆₀Nb₁₅Zr₁₀Si₁₅, Ti₃₉Zr₃₂Si₂₉, and Ti_65.5Fe_22.5Si₁₂—synthesized by arc melting and suction casting. Single-track laser remelting using a selective laser melting (SLM) system was performed to simulate additive manufacturing and examine microstructural evolution, cracking behavior, mechanical properties, and cytocompatibility. All alloys solidified into fully crystalline α/β-Ti matrices with Ti/Zr silicides; no amorphous structures were obtained. Laser remelting refined the microstructure but did not induce glass formation, consistent with the known limited glass-forming ability of Cu/Ni/Be-free Ti systems. Cracking was observed at low laser energies but crack density decreased as laser energy increased. Cracks were eliminated above ~0.4 J/mm for most alloys. Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃ exhibited the lowest stiffness (~125 GPa), while Ti₆₀Nb₁₅Zr₁₀Si₁₅ showed the highest due to silicide precipitation. Cytotoxicity tests (ISO 10993-5) confirmed all alloys to be non-toxic, with some extracts even enhancing fibroblast proliferation. This rapid laser-remelting approach enables cost-effective screening of Ti-based glass-forming alloys for additive manufacturing. Ti–Zr–Ta–Si systems demonstrated the most promising properties for further testing using the powder bed method. Full article

(This article belongs to the Section Biomaterials)

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18 pages, 5045 KB

Open AccessArticle

Effect of MB Value and Proportion of Reclaimed Powder on Mechanical Strength and Equivalent Cement Content of Cement-Stabilized Macadam

by Ouyang Lou, Junhao Li, Huaiping Xiao, Yingjun Jiang and Jiangang Xu

Materials 2025, 18(24), 5686; https://doi.org/10.3390/ma18245686 - 18 Dec 2025

Viewed by 547

Abstract

The fine clay content in reclaimed powder significantly influences the mechanical properties of cement-based materials. To promote the resource utilization of reclaimed powder in road engineering, using the methylene blue (MB) value as an indicator to evaluate the fine clay content of reclaimed [...] Read more.

The fine clay content in reclaimed powder significantly influences the mechanical properties of cement-based materials. To promote the resource utilization of reclaimed powder in road engineering, using the methylene blue (MB) value as an indicator to evaluate the fine clay content of reclaimed powder, the influence of the MB value and proportion of reclaimed powder on the mechanical strength of cement-stabilized macadam was analyzed; fitting equations for the relationship between reclaimed powder proportion and mechanical strength were constructed; the required MB value and optimal proportion of reclaimed powder were clarified; the impact of MB value variation on mechanical strength under optimal proportion conditions was evaluated; and with mechanical strength consistency as the principle, equivalence analysis between reclaimed powder proportion and cement content was conducted. The results indicate that when the MB value of reclaimed powder is less than 5.0 g/kg, the MB value has no obvious influence on the mechanical strength of cement-stabilized macadam. With increasing reclaimed powder content, both the compressive strength and splitting tensile strength of cement-stabilized macadam first increase and then decrease, reaching peak values at reclaimed powder contents of 3.0–4.0% and 5.0–5.5%, respectively. As cement content increases, the strength-enhancing effect of reclaimed powder weakens. The MB value of reclaimed powder should be less than 5.0 g/kg with a content of 4%. When cement content is 3–4%, based on mechanical strength equivalence, a reclaimed powder content of 4% can replace at least 0.4–0.5% of cement content. Full article

(This article belongs to the Special Issue Cement-Based/Non-Cement-Based Constructional Materials: Multiscale Mechanics under Diverse Loadings)

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17 pages, 3844 KB

Open AccessArticle

Strategy Construction to Improve the Thermal Resistance of Polyimide-Matrix Composites Based on Fiber–Resin Compatibility

by Yu Xing, Hongjiang Ni, Daijun Zhang, Jun Li and Xiangbao Chen

Materials 2025, 18(24), 5685; https://doi.org/10.3390/ma18245685 - 18 Dec 2025

Viewed by 632

Abstract

Carbon-fiber-reinforced thermoset polyimide composites have found wide applications in various aerospace areas. In this paper, the influence of carbon-fiber sizing on the thermal properties of polyimide composites was studied. Nonlinear detriment of the epoxy sizing was found to affect the composite’s thermal resistance. [...] Read more.

Carbon-fiber-reinforced thermoset polyimide composites have found wide applications in various aerospace areas. In this paper, the influence of carbon-fiber sizing on the thermal properties of polyimide composites was studied. Nonlinear detriment of the epoxy sizing was found to affect the composite’s thermal resistance. Furtherly, the mechanism, possibly responsible for the nonlinear detrimental effect of the epoxy sizing, was investigated through curing kinetics analysis and chemical structure characterization. Thermal curing activation energy change was found, possibly arising from the insertion of a flexible segment into the polyimide chain by epoxy–amine reaction. Based on the proposed mechanism, a strategy to manipulate the thermal resistance was established and verified. By the precuring of the carbon-fiber sizing, the polyimide composite exhibited obvious thermal resistance improvement, indicated by an enhancement of the glass transition temperature by 20 °C, and a weight-loss reduction under thermal aging at 400 °C by 25%. Simultaneously, a good fiber-matrix interface was maintained. This strategy provides a new route to enhance the thermal properties of polyimide composites from the viewpoint of carbon-fiber-matrix compatibility. Full article

(This article belongs to the Special Issue Structure and Mechanical Properties of Composite Materials)

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12 pages, 1617 KB

Open AccessArticle

Hybrid Tandem White Light-Emitting Diodes Based on GaN and Organic Emitters

by Jin-Zhe Xu, Xiao-Zhao Zhu, Feng Zhai, Wei-Zhi Liu, Dong-Ying Zhou and Liang-Sheng Liao

Materials 2025, 18(24), 5684; https://doi.org/10.3390/ma18245684 - 18 Dec 2025

Viewed by 678

Abstract

Tandem white organic light-emitting diodes (OLEDs), formed by stacking red, green, and blue organic electroluminescent units, offer a promising route toward high-resolution microdisplays. However, their performance is constrained by the intrinsically short lifetime of blue OLED sub-units. Replacing the unstable blue OLED with [...] Read more.

Tandem white organic light-emitting diodes (OLEDs), formed by stacking red, green, and blue organic electroluminescent units, offer a promising route toward high-resolution microdisplays. However, their performance is constrained by the intrinsically short lifetime of blue OLED sub-units. Replacing the unstable blue OLED with a long-lived GaN-based LED could address this limitation, but practical hybridization remains difficult because of incompatible fabrication routes and significant current imbalance between the inorganic and organic units. Here, we demonstrate the first hybrid GaN–OLED tandem white LEDs enabled by an interface-engineered charge-generation unit (CGU). By introducing an ITO/HAT-CN/LiNH₂-doped Bphen CGU, we simultaneously enhance the work function, strengthen the built-in electric field, and smooth the interfacial morphology. These synergistic effects promote efficient charge generation, yielding near-ideal voltage summation and well-balanced electron–hole injection. As a result, the hybrid tandem device shows a nearly twofold increase in current efficiency (from 28.1 to 58.6 cd A^–1) and significantly reduced spectral shift under varying current densities. We further demonstrate the generality of this approach by integrating the GaN emission with yellow OLEDs to produce stable blue–yellow hybrid white emission. This work establishes an applicable strategy for integrating GaN-LEDs and OLEDs, opening a pathway toward efficient, stable, and compact white light engines for next-generation microdisplay technologies. Full article

(This article belongs to the Special Issue Emerging Light-Emitting Materials and Devices)

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36 pages, 15395 KB

Open AccessArticle

Numerical and Experimental Approaches for Mechanical Durability Assessment of an EV Battery Pack Case

by Hyun Soo Kim, Mingoo Cho, Changyeon Lee, Jaewoong Kim and Sungwook Kang

Materials 2025, 18(24), 5683; https://doi.org/10.3390/ma18245683 - 18 Dec 2025

Viewed by 1053

Abstract

Electric vehicle (EV) battery pack cases (BPCs) must withstand mechanical loads such as impact, compression, and vibration to ensure structural integrity and passenger safety. This study evaluates the mechanical durability of a full-scale aluminum BPC using combined experimental testing and finite element analysis [...] Read more.

Electric vehicle (EV) battery pack cases (BPCs) must withstand mechanical loads such as impact, compression, and vibration to ensure structural integrity and passenger safety. This study evaluates the mechanical durability of a full-scale aluminum BPC using combined experimental testing and finite element analysis (FEA). A bottom impact test, 200 kN compression test, and power spectral density (PSD)-based random vibration test were conducted to simulate representative operating and handling conditions. The numerical model replicated boundary conditions and load profiles identical to the experiments, enabling a direct comparison of stress distribution and deformation characteristics. The results demonstrated that stress and displacement trends predicted by FEA closely matched experimental observations, with stress concentrations appearing at corner and frame junction regions and less than 1 mm deformation recorded under peak compression loading. Vibration responses were most pronounced in the vertical direction, without bolt loosening or structural damage. These results verify the reliability of the proposed BPC design and provide quantitative evidence supporting simulation-driven lightweight battery enclosure development. Full article

(This article belongs to the Special Issue High-Performance Materials for Energy Conversion)

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25 pages, 4446 KB

Open AccessArticle

Experimental Analysis of Pressure Sensor Membranes Intended for Vacuum Arc-Extinguishing Chambers in Medium-Voltage Switching Devices

by Paweł Węgierek, Damian Kostyła, Paweł Okal and Czesław Kozak

Materials 2025, 18(24), 5682; https://doi.org/10.3390/ma18245682 - 18 Dec 2025

Viewed by 549

Abstract

This article presents a comparison of empirical and simulation studies and the parameters declared by the membrane manufacturer. The analysis concludes that these values differ at each stage. Therefore, a numerical and simulation analysis of an optimal flat membrane was undertaken, which will [...] Read more.

This article presents a comparison of empirical and simulation studies and the parameters declared by the membrane manufacturer. The analysis concludes that these values differ at each stage. Therefore, a numerical and simulation analysis of an optimal flat membrane was undertaken, which will successfully perform measurement functions across the full pressure range without causing inelastic deformations based on a membrane made of 316 L stainless steel with the following mechanical parameters: Young’s modulus

E = 2 \times 10^{11} P a

, Poisson’s ratio

ν = 0.28

, density

ρ = 7980 k g / m^{3}

, and yield strength 2.8 × 10⁸ Pa. A diaphragm with an outer diameter of 25.4 mm, an inner diameter of

2.22 \times 10^{- 4} m

, and a thickness of t =

5.08 \times 10^{- 5} m

was designed for a pressure sensor in vacuum extinguishing chambers of medium-voltage devices, with a pressure difference

Δ p

from 7 × 10⁻⁴ Pa to 1.013 × 10⁵ Pa. Finite element method (FEM) simulations in the COMSOL Multiphysics environment showed maximum von Mises reduced stresses 1.96 × 10⁸ Pa below the yield strength, confirming operation in the linear-elastic range. The central deflection, described analytically by the equation

y = \frac{3 (1 - ν^{2}) P r^{4}}{16 E t^{3}}

, increased fivefold with an increase in diameter to

3.81 \times 10^{- 2} m

(active area A = 1.14 × 10⁻³ m² compared to 5.07 × 10⁻⁴ m²), achieving a metrological sensitivity of 9.1 × 10⁻¹⁰ m/Pa. Experimental studies integrated with Bragg FBG and epoxy adhesive (E = 5 × 10⁹ Pa, tensile strength

4.2 \times 10^{7} P a

) revealed a significant deviation from the manufacturer’s catalog data (e.g., deflection of

2.0 \times 10^{- 5} m

at

6.89 \times 10^{2} P a

), resulting from uneven bonding and a lack of coaxiality. Corrugated membranes with t =

2.0 \times 10^{- 5} m

exceeded plasticity, while the optimized configuration of a smooth membrane with rounded adhesive edges (

R = 1 \times 10^{- 4} m

) enabled precise pressure monitoring below

10^{- 1} P a

, despite technological restrictions on assembly and miniaturization. Full article

(This article belongs to the Section Materials Simulation and Design)

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6 pages, 192 KB

Open AccessEditorial

Recovery and Preparation of Innovative Products and Composite Materials for Environmental Applications

by Agnieszka Generowicz, Krzysztof Barbusiński and Maciej Thomas

Materials 2025, 18(24), 5681; https://doi.org/10.3390/ma18245681 - 18 Dec 2025

Viewed by 365

Abstract

The articles published in this Special Issue of the journal Materials, titled “Recovery and Preparation of Innovative Products and Composite Materials for Environmental Applications,” discuss the recovery and recycling of materials in the environmental field [...] Full article

(This article belongs to the Special Issue Recovery and Preparation of Innovative Products and Composite Materials for Environmental Applications)

20 pages, 6049 KB

Open AccessArticle

The Effect of Sc and Zr Additions on the Structure, Mechanical, and Corrosion Properties of a High Thermal Conductive Al–3%Zn–3%Ca Alloy

by Anastasia Lyskovich, Viacheslav Bazhenov, Ivan Baranov, Mikhail Gorshenkov, Olga Voropaeva, Andrey Stepashkin, Vitaliy Doroshenko, Ruslan Yu. Barkov, Shevket Rustemov and Andrey Koltygin

Materials 2025, 18(24), 5680; https://doi.org/10.3390/ma18245680 - 18 Dec 2025

Viewed by 786

Abstract

Al–Zn–Ca alloys are good candidates for industrial electronics and electric vehicles due to their high thermal conductivity, castability, and corrosion resistance, but their strength requires improvement. This study investigates how Sc and Zr additions affect the microstructure, thermal, mechanical, and corrosion properties of [...] Read more.

Al–Zn–Ca alloys are good candidates for industrial electronics and electric vehicles due to their high thermal conductivity, castability, and corrosion resistance, but their strength requires improvement. This study investigates how Sc and Zr additions affect the microstructure, thermal, mechanical, and corrosion properties of an Al–3 wt% Zn–3 wt% Ca base alloy. Microstructural analysis showed that substituting Sc with Zr did not drastically alter the phase composition but changed the elemental distribution: Sc was uniform, while Zr segregated to center of dendritic cell. Zr addition also refined the grain size from 488 to 338 μm. An optimal aging treatment at 300 °C for 3 h was established, which enhanced hardness for all alloys via precipitation of Al₃Sc/Al₃(Sc,Zr) particles. However, this Zr substitution reduced thermal conductivity (from 184.7 to 168.0 W/mK) and ultimate tensile strength (from 269 to 206 MPa), though it improved elongation at fracture (from 4.6 to 7.1%). All aged alloys exhibited high corrosion resistance in 5.7% NaCl + 0.3% H₂O₂ water solution, with Zr-containing variants showing a lower corrosion rate and better pitting resistance. The study confirms the potential of tuning Sc/Zr ratios in Al–Zn–Ca alloys to achieve a favorable balance of strength, ductility, thermal conductivity, and corrosion resistance. Full article

(This article belongs to the Section Metals and Alloys)

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11 pages, 5036 KB

Open AccessArticle

Plasmonic Arrays Resonating at D-Band Communication Frequencies

by Ruxue Wei, Meng Liu, Soren Petersen and Weili Zhang

Materials 2025, 18(24), 5679; https://doi.org/10.3390/ma18245679 - 18 Dec 2025

Viewed by 530

Abstract

We present systematic experimental studies of the impact of subwavelength structural geometries and electromagnetic field polarization on the resonance behavior of metallic metasurfaces at D-band frequencies. The measured influence of the photoconductive receiver antenna design in terahertz time-domain spectroscopy on the frequency-domain spectral [...] Read more.

We present systematic experimental studies of the impact of subwavelength structural geometries and electromagnetic field polarization on the resonance behavior of metallic metasurfaces at D-band frequencies. The measured influence of the photoconductive receiver antenna design in terahertz time-domain spectroscopy on the frequency-domain spectral features was analyzed. Numerical simulations reveal distinct resonance characteristics in the D-band regime, where extraordinary amplitude transmission is highly dependent on the array dimensions and field polarization orientation. The metasurface enables significant enhancements in surface electric fields and resonance response, attributed to the effective excitation of strong dipolar modes. These results demonstrate the extraordinary transmission capabilities of subwavelength metallic arrays and provide valuable insights for designing compact, low-loss, and tunable terahertz functional components needed in next-generation communications. Full article

(This article belongs to the Section Optical and Photonic Materials)

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18 pages, 6329 KB

Open AccessArticle

Study on Fatigue Behavior and Life Prediction of Laser Powder Bed Fused Ti6Al4V Alloy at 400 °C

by Liangliang Wu, Ruida Xu, Jiaming Zhang, Huichen Yu and Zehui Jiao

Materials 2025, 18(24), 5678; https://doi.org/10.3390/ma18245678 - 18 Dec 2025

Cited by 1 | Viewed by 660

Abstract

Additive manufacturing has huge development potential in the aerospace field. The hot-end components of aeroengines work in harsh environments, facing high temperatures and a demand for long service life. In this paper, high-cycle fatigue (HCF) tests of Ti6Al4V alloy at 400 °C by [...] Read more.

Additive manufacturing has huge development potential in the aerospace field. The hot-end components of aeroengines work in harsh environments, facing high temperatures and a demand for long service life. In this paper, high-cycle fatigue (HCF) tests of Ti6Al4V alloy at 400 °C by selective laser melting (SLM) under different stress ratios (−1, 0.1, 0.3, 0.5, and 0.8) were carried out, and the fracture surfaces were observed. The results show that the defects existing on the surface or subsurface are prone to become the origin of fatigue cracks. There is a large dispersion of the high-cycle fatigue life of the samples, especially at a low stress ratio. With the increase in the stress ratio, the fatigue failure area on the fracture surface gradually decreases, and the fracture surface gradually presents a mixed pattern of tensile endurance fracture and fatigue failure. Considering the influence of creep damage due to mean stress, models were established, respectively, for the fatigue behavior and time-related rupture behavior to predict fatigue life and conduct an assessment. Then, the two models were combined and the composite models were proposed using the linear damage law. Finally, the single fatigue model and rupture models, as well as the composite models, were evaluated, respectively, and compared with the actual fatigue life, and the best model was obtained for the high-cycle fatigue prediction of SLM Ti6Al4V at 400 °C. Full article

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11 pages, 1449 KB

Open AccessArticle

Study of Reaction Parameters for the Precise Synthesis of Low-Molecular-Weight Oligosiloxanes

by Satoru Saotome, Jiaorong Kuang, Yujia Liu, Takayuki Iijima and Masafumi Unno

Materials 2025, 18(24), 5677; https://doi.org/10.3390/ma18245677 - 17 Dec 2025

Viewed by 732

Abstract

This study investigates the influence of various parameters on the synthesis of oligosiloxanes with degrees of polymerization below 15. The work provides insights into methods for synthesizing oligosiloxanes with precisely controlled molecular weight and degrees of polymerization. Low-molecular-weight polysiloxanes with well-defined molecular characteristics [...] Read more.

This study investigates the influence of various parameters on the synthesis of oligosiloxanes with degrees of polymerization below 15. The work provides insights into methods for synthesizing oligosiloxanes with precisely controlled molecular weight and degrees of polymerization. Low-molecular-weight polysiloxanes with well-defined molecular characteristics have attracted attention due to their versatile functional properties and potential applications. Although some studies have explored the control of polysiloxane molecular weights, precise regulation of oligosiloxane molecular weight has been rarely investigated. This study aims to establish optimized reaction conditions for the synthesis of oligosiloxanes with precisely controlled molecular weights. The results reveal that the molecular weight of oligosiloxanes can be effectively tuned by adjusting the molar ratio between the promoter and initiator, the initiator and cyclotrisiloxane (D₃), as well as by varying the lithium type and solvent composition in the ring-opening polymerization of D₃. These findings provide valuable guidance for tailoring oligosiloxane properties and expanding their potential applications in advanced materials. Full article

(This article belongs to the Special Issue Functional Polymers for Energy, Biomedical and Electrical Applications)

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14 pages, 4436 KB

Open AccessArticle

Identification of Mechanical Parameters of the Silicon Structure of a Capacitive MEMS Accelerometer

by Kamil Kurpanik, Klaudiusz Gołombek, Edyta Krzystała, Jonasz Hartwich and Sławomir Kciuk

Materials 2025, 18(24), 5676; https://doi.org/10.3390/ma18245676 - 17 Dec 2025

Viewed by 1284

Abstract

The aim of this study was to conduct an advanced analysis of the MEMS sensor, including both experimental tests and numerical simulations, in order to determine its mechanical properties and operational dynamics in detail. It is challenging to find publications in the literature [...] Read more.

The aim of this study was to conduct an advanced analysis of the MEMS sensor, including both experimental tests and numerical simulations, in order to determine its mechanical properties and operational dynamics in detail. It is challenging to find publications in the literature that are not based on theoretical assumptions or general manufacturer data, which do not reflect the actual microstructural characteristics of the sensor. This study uses a numerical model developed in MATLAB/Simulink, which allows the experimentally determined material characteristics to be combined with predictive dynamic modelling. The model takes into account key mechanical parameters such as stiffness, damping and response to dynamic loads, and the built-in optimisation algorithm allows the structural parameters of the MEMS accelerometer to be estimated directly from experimental data. In addition, SEM microscopic studies and EDS chemical composition analysis provided detailed information on the sensor’s microstructure, allowing its impact on mechanical properties and dynamic parameters to be assessed. The integration of advanced experimental methods with numerical modelling has resulted in a model whose response closely matches the measurement results, which is an important step towards further research on design optimisation and improving the reliability of MEMS sensors in diverse operating conditions. Full article

(This article belongs to the Special Issue Multiscale Mechanical Behaviors of Advanced Materials and Structures)

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22 pages, 6575 KB

Open AccessArticle

Thermal [2+2] Cycloaddition Reactions of Perfluorobicyclo[2.2.0]hex-1(4)-ene with Ethylene, Benzene and Styrene: A MEDT Perspective

by Agnieszka Kącka-Zych and Luis R. Domingo

Materials 2025, 18(24), 5675; https://doi.org/10.3390/ma18245675 - 17 Dec 2025

Viewed by 852

Abstract

Thermal [2+2] cycloaddition (22CA) reactions of perfluorobicyclo[2.2.0]hex-1(4)-ene (PFBHE) and bicyclo[2.2.0]hex-1(4)-ene (BHE) with ethylene, benzene and styrene were investigated through the Molecular Electron Density Theory (MEDT) at the UM06-2X/6-311G(d,p) level in benzene. Scrutiny of the DFT-based reactivity indices indicates that the presence of the [...] Read more.

Thermal [2+2] cycloaddition (22CA) reactions of perfluorobicyclo[2.2.0]hex-1(4)-ene (PFBHE) and bicyclo[2.2.0]hex-1(4)-ene (BHE) with ethylene, benzene and styrene were investigated through the Molecular Electron Density Theory (MEDT) at the UM06-2X/6-311G(d,p) level in benzene. Scrutiny of the DFT-based reactivity indices indicates that the presence of the eight fluorines in PFBHE notably expands the electrophilic nature of this species, participating in polar reactions. These 22CAs proceed through a stepwise mechanism, while the non-polar 22CA reaction of BHE with ethylene requires high energy around 26.6 kcal·mol⁻¹, the polar 22CA reaction of PFBHE with styrene requires a low activation energy of 13.2 kcal·mol⁻¹. The polar 22CA reaction of PFBHE with benzene presents the highest activation energy, 28.3 kcal·mol⁻¹, because of the loss of its aromatic character. Scrutiny of the electron localization function (ELF) at the TSs associated with the first step points that the creation of the C1–C3 bond set about, while that at the TSs associated with the ring-closure means that the creation of the C2–C4 bond has not started yet. At the end, a Relative Interacting Atomic Energy (RIAE) study of these thermal 22CA processes shows that while at the non-polar TS1a-I both interacting frameworks are electronically destabilized, at the polar TS1a-IV, the hefty global electron density transfer (GEDT) goes ahead towards PFBHE, causing a strong electronic stabilization of this framework, markedly reducing the RIAE activation energy. Full article

(This article belongs to the Special Issue Materials Science Advancements Through Density Functional Theory)

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20 pages, 5129 KB

Open AccessArticle

Evaluation of the Effect of Polyurea Coating Application on the Capacity and Deformability of Reinforced Concrete Beams

by Artur Matusiak, Tomasz Waśniewski and Jacek Szafran

Materials 2025, 18(24), 5674; https://doi.org/10.3390/ma18245674 - 17 Dec 2025

Cited by 2 | Viewed by 549

Abstract

Polyurea coatings as a possible structural reinforcement system is a research project involving the investigation of the potential of using polyurea coatings to improve the performance characteristics of structures (steel, concrete, timber and others used in construction). This study, which is part of [...] Read more.

Polyurea coatings as a possible structural reinforcement system is a research project involving the investigation of the potential of using polyurea coatings to improve the performance characteristics of structures (steel, concrete, timber and others used in construction). This study, which is part of the aforementioned project, focuses on evaluating the effect of polyurea coating application on the strength and deformability parameters of reinforced concrete elements. For the purposes of this publication, nonlinear cross-sectional analyses were carried out using a layered model, and the model was then calibrated and verified against experimental results. The study was supplemented by a numerical analysis of a reinforced concrete beam coated with polyurea, and the adopted numerical model was calibrated and verified using experimental results. For the calibration and verification of the computational models, experimental tests of reinforced concrete beams with a low degree of reinforcement (0.7%), were used. The results of the numerical analyses are consistent with those of the experimental studies, and an increasing effect of the polyurea coating is demonstrated with thicker layers of its application. Numerical analysis shows that the reinforcement ratio had a strong influence on the effectiveness of the polyurea coating. Full article

(This article belongs to the Section Construction and Building Materials)

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19 pages, 4399 KB

Open AccessArticle

The Influence of Low-Emission Mineral Additives as a Substitute for CEM II and CEM III Cement on the Properties of Cement Mortars

by Paweł Muzolf, Grzegorz Rogojsz and Tomasz Rudnicki

Materials 2025, 18(24), 5673; https://doi.org/10.3390/ma18245673 - 17 Dec 2025

Viewed by 390

Abstract

The main goal of the research was to determine whether it was possible to reduce the cement content in mortar without compromising strength parameters. This is crucial for reducing the carbon footprint associated with cement production. In this article, the authors presented the [...] Read more.

The main goal of the research was to determine whether it was possible to reduce the cement content in mortar without compromising strength parameters. This is crucial for reducing the carbon footprint associated with cement production. In this article, the authors presented the results of research evaluating the effect of selected mineral additives on the strength properties of standard mortar after 7, 28, and 56 days of curing. The analysis of the effect of mineral additives was performed for CEM II and CEM III cements and seven selected mineral additives: white microsilica, Mikrosill+ microsilica, limestone powder, glass powder, glass granulate, and basalt powder. The study considered the use of mineral additives at 10% and 20% by weight of cement as a substitute. During the analysis of the test results, it was observed that the use of white microsilica and Mikrosill+ at 10% and 20% increased strength by approximately 50% compared to the reference samples. Importantly, strength was 50% higher with a 20% reduction in cement content. A positive effect of additives on strength parameters was observed only for CEMII cement. In the case of CEMIII cement, mineral additives reduce compressive strength. Full article

(This article belongs to the Section Construction and Building Materials)

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14 pages, 5339 KB

Open AccessCommunication

Enhancing Electromigration Lifetime Through Controlled Reduction of Bismuth Content in Sn-Bi-Ag Solder Interconnects

by Shengbo Wang, Shuai Meng, Houlin Liu and Mingliang Huang

Materials 2025, 18(24), 5672; https://doi.org/10.3390/ma18245672 - 17 Dec 2025

Viewed by 456

Abstract

This study systematically investigates the influence of Bi content on the electromigration (EM) lifetime of low-temperature Cu/Sn-xBi-1Ag (600 μm)/Cu interconnects, where x = 57, 47 and 40 wt.%. The intrinsically higher product of diffusivity and effective charge number (DZ*) for Bi [...] Read more.

This study systematically investigates the influence of Bi content on the electromigration (EM) lifetime of low-temperature Cu/Sn-xBi-1Ag (600 μm)/Cu interconnects, where x = 57, 47 and 40 wt.%. The intrinsically higher product of diffusivity and effective charge number (DZ*) for Bi compared to Sn drives pronounced preferential migration of Bi atoms towards the anode, resulting in progressive β-Sn/Bi phase separation and linear thickening of a Bi-rich layer at the anode. Reducing the Bi content suppresses the EM-induced atomic flux (J_EM) through three principal mechanisms: (i) a decrease in the atomic concentration of mobile Bi atoms; (ii) a reduction in electrical resistivity that weakens the electron wind force; and (iii) an increase in lattice diffusion distance that lowers the effective diffusion coefficient (D_eff). The suppression of J_EM directly governs the thickening kinetics of anodic Bi layer, as evidenced by the close agreement between the calculated (1:0.40:0.23) and measured (1:0.45:0.26) anodic Bi layer growth rate ratios. Consequently, the EM lifetime is significantly extended from 62.3 h (Sn-57Bi-1Ag) to 164.9 h (Sn-47Bi-1Ag) and 414.1 h (Sn-40Bi-1Ag), representing 2.6-fold and 6.6-fold improvements, respectively. This study highlights that reducing the Bi content is an effective strategy for enhancing the EM reliability of Sn-Bi-Ag solder interconnects. Full article

(This article belongs to the Special Issue Research Advances in Microelectronics Packaging and Devices: From Materials to Reliability)

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10 pages, 2468 KB

Open AccessCommunication

Evolution of Cluster Morphology and Its Impact on Dislocation Behavior in a Strip-Cast HSLA Steel

by Huiwen Yu, Yuhe Huang, Jun Lu, Junheng Gao, Haitao Zhao, Honghui Wu, Chaolei Zhang, Shuize Wang and Xinping Mao

Materials 2025, 18(24), 5671; https://doi.org/10.3390/ma18245671 - 17 Dec 2025

Viewed by 435

Abstract

Strip casting presents a sustainable route for producing advanced steels, such as high-strength low-alloy (HSLA) grades. This study investigated how early-stage isothermal holding (120–1800 s at 923 K) affects the evolution of cluster morphology and its subsequent impact on dislocation behavior and mechanical [...] Read more.

Strip casting presents a sustainable route for producing advanced steels, such as high-strength low-alloy (HSLA) grades. This study investigated how early-stage isothermal holding (120–1800 s at 923 K) affects the evolution of cluster morphology and its subsequent impact on dislocation behavior and mechanical properties in a strip-cast Nb-bearing HSLA steel. Advanced characterization (atom probe tomography) revealed that prolonged holding promotes the growth of nanoscale Nb-(C,N) clusters and precipitates, accompanied by an increase in ferrite fraction. Remarkably, this evolution simultaneously enhances both strength and ductility. Enhanced ductility and sustained work hardening are linked to a higher density and volume fraction of nanoscale particles, which act as potent obstacles for dislocation nucleation and multiplication. These findings establish a critical link between cluster evolution and dislocation-mediated strengthening, providing a basis for optimizing strip-cast steels. Full article

(This article belongs to the Special Issue Advanced Sheet/Bulk Metal Forming)

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14 pages, 4168 KB

Open AccessArticle

Effect of Laser Shock Peening Times on Low-Cycle Fatigue Properties and Fracture Mechanism of Additive TA15 Titanium Alloy

by Xu Pei, Sailan Wang, Zhaomei Xu, Zhouzhi Gu, Yuchun Peng and Pengfei Li

Materials 2025, 18(24), 5670; https://doi.org/10.3390/ma18245670 - 17 Dec 2025

Cited by 1 | Viewed by 594

Abstract

This study investigates the effects of multiple laser shock peening (LSP) treatments on the low-cycle fatigue performance and fracture mechanisms of laser-melted, additive-manufactured Ti-6.5Al-1Mo-1V-2Zr (TA15) titanium alloy. The primary objective is to systematically evaluate how different LSP impact numbers (0, 1, and 2 [...] Read more.

This study investigates the effects of multiple laser shock peening (LSP) treatments on the low-cycle fatigue performance and fracture mechanisms of laser-melted, additive-manufactured Ti-6.5Al-1Mo-1V-2Zr (TA15) titanium alloy. The primary objective is to systematically evaluate how different LSP impact numbers (0, 1, and 2 impacts) enhance fatigue life and alter fracture behavior. Low-cycle fatigue life was determined via tensile-compression fatigue testing. Microfracture morphology was examined using scanning electron microscopy (SEM), surface residual stresses were measured by X-ray diffraction (XRD), and microhardness tests were conducted concurrently. Results indicate that LSP significantly enhances fatigue life: fatigue life increased by 2.34 times and 2.56 times after one and two LSP impacts, respectively, compared to the untreated state. As impact cycles increased, the microhardness of the material surface rose by 8.51% and 14.53%, respectively, with residual compressive stresses reaching −145 MPa and −183 MPa. Concurrently, LSP-2 treatment formed a refined microstructure featuring coexisting lamellar α and acicular martensite in the surface layer. This strengthening effect is attributed to LSP-induced surface residual compressive stress, grain refinement, and the resulting migration of fatigue crack initiation from the surface to subsurface regions. These findings provide critical insights for optimizing fatigue-resistant designs of additively manufactured titanium alloy components. Full article

(This article belongs to the Special Issue Advances in Metal Coatings for Wear and Corrosion Applications (Second Edition))

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50 pages, 1671 KB

Open AccessReview

Dynamic Tensile Strength of Concrete: A Review of Mechanisms, Test Results, and Applications for Dam Safety

by Anderssen Barbosa dos Santos, Pedro Alexandre Conde Bandini, Rocio Lilen Segura and Patrick Paultre

Materials 2025, 18(24), 5669; https://doi.org/10.3390/ma18245669 - 17 Dec 2025

Viewed by 1032

Abstract

This paper provides a comprehensive review of the dynamic tensile behavior of concrete, focusing on its implications for seismic-resistant and impact-prone structures such as dams. The present work distinguishes itself in the following ways: providing the first comprehensive synthesis explicitly focused on large-aggregate [...] Read more.

This paper provides a comprehensive review of the dynamic tensile behavior of concrete, focusing on its implications for seismic-resistant and impact-prone structures such as dams. The present work distinguishes itself in the following ways: providing the first comprehensive synthesis explicitly focused on large-aggregate dam concrete behavior across the seismic strain rate range (

10^{- 4}

to

10^{- 2}

s⁻¹), which is critical yet underrepresented in the existing literature; integrating recent experimental and numerical advances regarding moisture effects, load history, and cyclic loading—factors that are essential for dam safety assessments; and critically evaluating current design guidelines for concrete dams against state-of-the-art research to identify gaps between engineering practice and scientific evidence. Through the extensive synthesis of experimental data, numerical simulations, and existing guidelines, the study examines key factors influencing dynamic tensile strength, including strain rate effects, crack evolution, testing techniques, and material variables such as moisture content, load history, and aggregate size. Experimental results from spall tests, split Hopkinson pressure bar configurations, and cyclic loading protocols are analyzed, revealing dynamic increase factors ranging from 1.1 to over 12, depending on the strain rates, saturation levels, and preloading conditions. The roles of inertial effects, free water (via the Stefan effect), and microstructural heterogeneity in enhancing or diminishing tensile performance are critically evaluated. Numerical models, including finite element, discrete element, and peridynamic approaches, are discussed for their ability to simulate crack propagation, inertia-dominated responses, and moisture interactions. The review identifies and analyzes current design guidelines. Key conclusions emphasize the necessity of integrating moisture content, load history, and mesoscale heterogeneity into dynamic constitutive models, alongside standardized testing protocols to bridge gaps between laboratory data and real-world applications. The findings advocate for updated engineering guidelines that reflect recent advances in rate-dependent fracture mechanics and multi-scale modeling, ensuring safer and more resilient concrete infrastructure under extreme dynamic loads. Full article

(This article belongs to the Special Issue Structural, Physical and Mechanical Properties of Reinforced Concrete, Novel Cementitious Composites and Other Brittle Construction Materials)

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27 pages, 4159 KB

Open AccessArticle

Research on Intelligent Control Method of Camber for Medium and Heavy Plate Based on Machine Vision

by Chunyu He, Chunpo Yue, Zhong Zhao, Zhiqiang Wu and Zhijie Jiao

Materials 2025, 18(24), 5668; https://doi.org/10.3390/ma18245668 - 17 Dec 2025

Viewed by 469

Abstract

With the continuous development of intelligent manufacturing in the iron and steel industry, there are increasing requirements for the quality control and precision of steel products. Camber is one of the critical defects affecting product quality in medium and heavy plates. Its occurrence [...] Read more.

With the continuous development of intelligent manufacturing in the iron and steel industry, there are increasing requirements for the quality control and precision of steel products. Camber is one of the critical defects affecting product quality in medium and heavy plates. Its occurrence during the rolling process not only reduces the yield of plates but also leads to serious production accidents such as rolling scrap and equipment damage, increasing the operational costs of enterprises. Addressing the difficulties that camber is influenced by complex factors and direct modeling control is challenging, this study proposes a camber detection and control method for medium and heavy plates based on image processing and machine learning algorithms, relying on an actual plate production line. The Optuna-XGBoost model is used to mine and train the production data of plates rolling, extracting the optimal control experience of operators as the pre-control values for camber. The Optuna-XGBoost model achieves an R² of 0.9999 on the training set and 0.9794 on the test set, demonstrating excellent fitting performance. Meanwhile, a camber detection technology during the plate rolling process is developed based on machine vision. A feedback control model for camber of medium and heavy plates based on distal lateral movement is established. The combined application of pre-control and feedback control reduces the occurrence of camber, ensuring the overall flatness of steel plates during the rolling process. This paper establishes an intelligent control framework for plate camber, synergized by data-driven pre-control and machine vision-based feedback control, offering a novel approach for the online optimal control of complex nonlinear industrial processes. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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25 pages, 4569 KB

Open AccessArticle

On Numerical and Analytical Investigation of the Effectiveness of Strengthening of Steel Columns—Case Study

by Jacek Szafran, Paulina Świątkiewicz and Paulina Kaszubska

Materials 2025, 18(24), 5667; https://doi.org/10.3390/ma18245667 - 17 Dec 2025

Viewed by 471

Abstract

In the context of growing environmental consciousness, the contemporary construction industry is placing significant emphasis on prolonging the functional lifespan of existing infrastructure. In the event of a modification in the utilisation of a building, an augmentation in the loads transferred to individual [...] Read more.

In the context of growing environmental consciousness, the contemporary construction industry is placing significant emphasis on prolonging the functional lifespan of existing infrastructure. In the event of a modification in the utilisation of a building, an augmentation in the loads transferred to individual elements, or a deterioration in the condition of the structure due to wear and tear, it is often necessary to implement measures for structural reinforcement. The present paper sets out an analysis of the effectiveness of strengthening a steel column manufactured from SHS120×120×5. It was posited that four distinct reinforcement variants could be achieved by the implementation of additional stiffening elements through the process of welding. The efficiency analysis was conducted employing two distinct methodologies. The geometrical imperfection method is employed using the IDEAStatiCa Member 25.0.4 software, whilst the analytical method is implemented through the use of guidelines presented in the literature. It was demonstrated that all of the proposed solutions were capable of meeting the required column capacity when the loads were increased. A comparison was made between the values of the critical forces and the members’ stresses, determined by the selected methods. A substantial discrepancy was identified between the critical force values derived from linear buckling analysis and those calculated using elastic Euler theory. The following discourse herein delineates the primary advantages and limitations of the two aforementioned methods. Full article

(This article belongs to the Section Construction and Building Materials)

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