Railway Engineering Science (铁道工程科学)•2026•DOI: 10.1007/s40534-025-00398-0
Ventilation is one of the most effective ways to improve the air quality in trains. Top exhaust and bottom exhaust are two commonly used modes. The study hopes to switch the exhaust mode to adapt to the indoor requirements of different scenes without changing the layout of the end pipe. In the study, the airflow characteristics, energy consumption, thermal comfort and air quality in the compartment are evaluated based on computational fluid dynamics. The results show that the energy consumption decreases with the increase of the top exhaust air volume in summer conditions, while the opposite is true in winter conditions. In terms of thermal comfort, combining top and bottom exhaust can effectively improve air speed index, temperature difference index and air diffusion performance index. In addition, the draft rate index and percent dissatisfied index are less than 10% and 3%, respectively, which meet the requirements of ISO 7730 standard. In terms of air quality, the average pollutant concentration inside the vehicle decreased, but the longitudinal penetration capacity of the pollutant has increased. The research results can provide some suggestions and help for the ventilation design of high-speed trains.
Journal of Advanced Ceramics•2026•DOI: 10.26599/JAC.2026.9221338
Si3N4 fiber-reinforced ceramic composites are candidate materials for high-temperature wave-transparent applications, yet the relationships among composition, interfacial characteristics, and mechanical performance remain inadequately understood. This study designs three composites—Si3N4f/BN, Si3N4f/SiO2, and Si3N4f/SiO2–BN—and systematically investigates their performances. The reaction between BN precursors and silanol groups in the SiO2 matrix during fabrication of Si3N4f/SiO2–BN enhances chemical compatibility between fiber and matrix, promoting elemental interdiffusion and forming a thicker interfacial diffusion region. Consequently, the interfacial shear strength of Si3N4f/SiO2–BN is 1.86 and 2.35 times that of Si3N4f/BN and Si3N4f/SiO2, respectively. The stronger fiber-matrix bonding in Si3N4f/SiO2–BN suppresses fiber pull-out, whereas weaker bonding in the other two composites permits it. Si3N4f/BN primarily exhibits fiber bundle pull-out, whereas Si3N4f/SiO2 shows long single-fiber pull-out, indicating improved damage tolerance. In contrast, Si3N4f/SiO2–BN displays typical brittle fracture behavior with minimal fiber pull-out and degraded mechanical properties. Excessive interfacial bonding, together with thermal residual stress arising from thermal expansion mismatch between the Si3N4 fiber and the matrix, degrades flexural and compressive strengths. Moreover, this excessive bonding restricts interfacial debonding and fiber pull-out, leading to a brittle fracture mode. Despite differences in interfacial microstructure, all three composites exhibit good dielectric properties. The use of SiO2 and BN matrices effectively reduces both the dielectric constant and the dielectric loss tangent of Si3N4 fiber-reinforced ceramic composites. These findings provide valuable insights into the design of high-temperature wave-transparent composites operated in extreme environments.
Nano-Micro Letters•2026•DOI: 10.1007/s40820-025-01990-z
Lithium-oxygen (Li-O2) battery is favored among “beyond lithium-ion” technologies for sustainability because of its exceptional energy density. Major impediments are the poor cycle stability and grievous capacity degradation at high current densities. We address these issues by a “killing two birds with one stone” O2-pressure protocol. It first resolves efficient O2 mass transport at high rates. The accelerated reaction kinetics optimizes the composition and growth pathway of discharge products. This protocol secondly achieves protection of Li anodes via densifying corrosion layers on them. Consequently, the battery delivers both ultrahigh discharge capacity (> 9,000 mAh g−1) at 3,000 mA g−1 and excellent cycling stability. Under a dual-strategy effect of high-pressure O2 and artificial protection layers, the battery actualizes over 11-fold increase in cycle life of 5,170 h (2,585 cycles). The strategy opens avenues for advancing Li-O2 batteries towards practical application and confers the extension to other gas-based batteries.
Journal of Central South University•2026•DOI: 10.1007/s11771-026-6295-1
Affected by the depositional environment, coal seams in the weathered and oxidized zone and their overlying strata are characterized by developed fractures and poor self-stability, leading to difficulties in roadway and working face roof management. This paper analyzes the failure characteristics of coal-rock masses in this zone. Combined with model tests and numerical simulation methods, it investigates the stress distribution status, deformation-failure characteristics, and movement-fracture laws of the overlying strata in a fully mechanized top-coal caving working face. The results indicate: (1) Weathering and oxidation significantly degrade strength and increase plastic deformation in coal-rock masses; (2) Under mining-induced disturbance, overlying strata stress is released from the in-situ state and sharply reduced, forming stress concentration zones ahead of the coal wall and at face ends; (3) During mining, fractures propagating upwards from the coal wall trigger rib spalling and top-coal collapse, forming combined cantilever and articulated rock beam structures. The overlying strata sequentially undergo four deformation-failure stages: "bed separation, immediate roof fracture, main roof fracture, and high-level strata collapse". The research findings can provide a basis for the safe mining of fully mechanized top-coal caving faces in weathered and oxidized coal.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01822-0
In photocatalytic water treatment processes, the particulate photocatalysts are typically immobilized on membrane, through either chemical/physical loading onto the surface or directly embedding in the membrane matrix. However, these immobilization strategies inevitably compromise the interfacial mass diffusion and cause activity decline relative to the suspended catalyst. Here, we propose a binder-free surface immobilization strategy for fabrication of high-activity photocatalytic membrane. Through a simple dimethylformamide (DMF) treatment, the nanofibers of polyvinylidene fluoride membrane were softened and stretched, creating enlarged micropores to efficiently capture the photocatalyst. Subsequently, the nanofibers underwent shrinking during DMF evaporation, thus firmly strapping the photocatalyst microparticles on the membrane surface. This surface self-bounded photocatalytic membrane, with firmly bounded yet highly exposed photocatalyst, exhibited 4.2-fold higher efficiency in hydrogen peroxide (H2O2) photosynthesis than the matrix-embedded control, due to improved O2 accessibility and H2O2 diffusion. It even outperformed the suspension photocatalytic system attributed to alleviated H2O2 decomposition at the hydrophobic surface. When adopted for UV-based water treatment, the photocatalytic system exhibited tenfold faster micropollutants photodegradation than the catalyst-free control and demonstrated superior robustness for treating contaminated tap water, lake water and secondary wastewater effluent. This immobilization strategy can also be extended to the fabrication of other photocatalytic membranes with diverse catalyst types and membrane substrate. Overall, our work opens a facile avenue for fabrication of high-performance photocatalytic membranes, which may benefit advanced oxidation water purification application and beyond.
China Foundry•2025•DOI: 10.1007/s41230-025-4031-3
Columnar to equiaxial crystal transition (CET) is an important technological feature in many casting processes. This work investigated the CET during the solidification of Mg-Gd-Zn alloys by combining synchrotron radiation in-situ imaging and phase-field method. Results show that the grain size, dendrite tip radius, and secondary dendrite arm spacing (SDAS) all exponentially decrease with an increase in cooling rate (Vc). The variation in the radius of the dendritic tip is similar to the prediction of the Hunt model, while the variation in the SDAS is close to the Bouchard-Kirkaldy model. It is worth noting that the CET is promoted by a decrease in the temperature gradient (G) and an increase in the cooling rate (Vc). In both equiaxed and columnar crystal regions, the dendrite tip growth rate and solid phase volume fraction increase with increasing G and Vc. In addition, the CET process has been predicted by simulation. The results are consistent with the predictions of the GTK model, which is important for the in-depth study of the dendrite morphology in different crystallization regions. In the final stage, the effects of different critical subcooling degrees and nucleation densities on the CET were explored. The results show that increasing the critical nucleation supercooling degree can inhibit the generation of equiaxial crystals, while increasing the nucleation density helps to promote the CET.
New Carbon Materials (新型炭材料)•2025•DOI: 10.1016/S1872-5805(NCM2025-6-2)
Because of their excellent low-temperature (−15 to −40 °C) tolerance, sodium-ion batteries are emerging as a complement to lithium-ion batteries for use in extremely cold environments (e.g. high-latitude areas). Hard carbon has a high low-voltage sodium storage capacity and a good initial efficiency, making it one of the most promising anode materials for sodium-ion batteries. It has a complex structure, featuring closed pores, nano graphitic domains, and surface functional groups. The sodium storage sites in hard carbon are reviewed as are the widely accepted sodium storage mechanisms. The main factors contributing to the degradation of the good low-temperature performance in hard carbon anodes are considered, including sodium dendrite formation, low ion diffusion rates, and surface-side reactions. Finally, strategies to increase the low-temperature sodium storage performance of hard carbon anodes are summarized, including bulk structure design, and improvements in interfaces and cut-off voltage. Guidance is provided for improving the low-temperature performance of hard carbon anodes to accelerate the development of these batteries.
Journal of Semiconductors (半导体学报 - 中国科学院半导体研究所)•2025•DOI: 10.1088/1674-4926/25050007
Perovskite solar cells (PSCs) have emerged as a highly promising photovoltaic technology, achieving power conversion efficiencies exceeding 25%. However, stability remains a critical challenge due to degradation under heat, moisture, and operational stress. Fullerenes, particularly C60 and its derivative PCBM, have been widely used as electron-transport materials in PSCs, but they offer limited interfacial stabilization. Recent innovative approaches have focused on designing fullerene-based materials that not only facilitate electron conduction but also actively enhance and protect the perovskite interface for long-term stability. One approach involves a magnetic endohedral metallofullerene (Nd@C82) integrated into a polymer matrix (PMMA) to form a robust interface layer. This Nd@C82-PMMA layer simultaneously enhances electron extraction and provides in-situ encapsulation, achieving a remarkable power conversion efficiency of 26.78% (certified 26.29%) on small-area cells and 23.08% on a 16 cm2 module. Unencapsulated cells retained approximately 82% of their initial efficiency after 2500 h at 65°C and over 99% after 1000 h under damp-heat conditions. Another strategy involves chemically modifying C60 to create an ionic salt (CPMAC) that forms stronger electrostatic coupling with the perovskite, reducing interfacial defects and enhancing mechanical toughness. CPMAC-based cells achieved efficiencies up to ~26%, about 0.6% higher than pristine C60, and exhibited only one-third of the performance drop over 2000 h under thermal and humidity stress. These innovations demonstrate synergistic optimization of efficiency and durability in perovskite photovoltaics.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.04.004
Dynamic stress adjustment in deep-buried high geostress hard rock tunnels frequently triggers catastrophic failures such as rockbursts and collapses. While a comprehensive understanding of this process is critical for evaluating surrounding rock stability, its dynamic evolution is often overlooked in engineering practice. This study systematically summarizes a novel classification framework for stress adjustment types—stabilizing (two-zoned), shallow failure (three-zoned), and deep failure (four-zoned)—characterized by distinct stress adjustment stages. A dynamic interpretation technology system is developed based on microseismic monitoring, integrating key microseismic parameters (energy index EI, apparent stress ra, microseismic activity S), seismic source parameter space clustering, and microseismic paths. This approach enables precise identification of evolutionary stages, stress adjustment types, and failure precursors, thereby elucidating the intrinsic linkage between geomechanical processes (stress redistribution) and failure risks. The study establishes criteria and procedures for identifying stress adjustment types and their associated failure risks, which were successfully applied in the Grand Canyon Tunnel of the E-han Highway to detect 50 instances of disaster risks. The findings offer invaluable insights into understanding the evolution process of stress adjustment and pinpointing the disaster risks linked to hard rock in comparable high geostress tunnels.
China Foundry•2025•DOI: 10.1007/s41230-025-3113-6
Annealing treatment is an effective strategy to enhance the comprehensive properties of Mg-8Li-3Al-2Zn (LAZ832) alloy, where the cooling rate plays a decisive role in tailoring microstructure and performance. This study systematically investigates the effects of cooling rates, controlled via water quenching (WC), air cooling (AC), and furnace cooling (FC), on the phase evolution, mechanical properties, and corrosion resistance of LAZ832. The annealed microstructure consists of α-Mg, β-Li, AlLi, and MgLi2Al phases, and the volume fraction of Al-Li phases (AlLi and MgLi2Al) increases as the cooling rate decreases. Strengthening mechanisms are dominated by solid solution strengthening, driven by the dissolution of Al and Zn atoms into the matrix, which significantly enhances tensile strength. However, excessive solute content leads to a marked decline in ductility. Scanning probe microscope (SPM) reveals an elevated work function due to the dissolution of Al and Zn atoms into the matrix phase, correlating with improved corrosion resistance. Comprehensive analysis demonstrates that air cooling achieves an optimal balance between tensile strength, ductility, and corrosion resistance, outperforming furnace-cooled samples and offering a pragmatic compromise compared to water-quenched specimens with higher strength but brittle failure. These findings establish a robust framework for designing LAZ832 alloys with tailored microstructures and multi-property optimization, advancing their application in lightweight engineering fields.
China Foundry•2025•DOI: 10.1007/s41230-025-4171-5
In order to investigate the segregation process and clarify its effect on the formation of TiN during the solidification of a micro-alloy steel containing titanium (Ti), a new mathematical model concerning solute transportation, solidification, as well as TiN precipitation was successfully established and verified. The transportation of solute elements was described using the Brody-Fleming microsegregation model, while the thermodynamic principles governing the precipitation of TiN were derived within the framework of the model. Additionally, the model accounts for variations in the diffusion coefficient due to phase transition and the influence of non-equilibrium solidification on solute distribution. High-temperature tests were conducted to validate the mathematical model. Results show that during solidification, due to selective crystallization, there is positive segregation of Ti and N in the solidifying front. What’s more, due to the high cooling rate near the surface of this steel, negative segregation is easier to be formed in the surface area. The highest concentration of TiN precipitation is found in the 1/4 width of this steel. High-temperature experiment shows that when the solidifying front reaches the 1/4 width of the specimen, the concentration product of Ti and N elements biased at the solidifying front reaches the thermodynamic conditions of TiN precipitation, and exists a higher concentration of TiN distributed in this region. To address this phenomenon, a comparative analysis of the effects of cooling rate and initial solute element content on TiN precipitation behavior was conducted. An increase in the surface cooling rate accelerates the progression of the solidification front and diminishes solute segregation near the front, thereby reducing TiN precipitation. However, with the increase of the initial solute element content, the concentration product of Ti and N elements rises, then the content of TiN precipitation increases. The results of this model provide important insight into the micro segregation and TiN precipitation mechanism of the micro-alloy steels bearing titanium.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-025-3159-x
Developing highly active and stable air electrodes remains challenging for reversible solid oxide cells (R-SOCs). Herein, we report an A-site high-entropy engineered perovskite oxide, La0.2Pr0.2Nd0.2Ba0.2Sr0.2Co0.8Fe0.2O3−δ (HE-LSCF), and its electrocatalytic activity and stability property are systematically probed for tubular R-SOCs. The HE-LSCF air electrode exhibits excellent oxygen reduction reaction (ORR) activity with a low polarization resistance of 0.042 Ω·cm2 at 700°C, which is much lower than that of La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF), indicating the excellent catalytic activity of HE-LSCF. Meanwhile, the tubular R-SOCs with HE-LSCF shows a high peak power density of 1.18 W·cm−2 in the fuel cell mode and a promising electrolysis current density of −0.52 A·cm−2 at 1.5 V in the electrolysis mode with H2 (~10% H2O) atmosphere at 700°C. More importantly, the tubular R-SOCs with HE-LSCF shows favorable stability under 180 h reversible cycling test. Our results show the high-entropy design can significantly enhance the activity and robustness of LSCF electrode for tubular R-SOCs.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3005-6
Thermal and mechanical properties of yttrium tantalate (YTaO4), a top coat ceramic of thermal barrier coatings (TBCs) for aeroengines, are enhanced by synthesizing Y1−xTa1−xM2xO4 (M = Ti, Zr, Hf; x = 0.06, 0.12, 0.18, 0.24) medium-entropy ceramics (MECs) using a two-step sintering method. In addition, the thermal conductivity, thermal expansion coefficients (TECs), and fracture toughness of MECs were investigated. An X-ray diffraction study revealed that the Y1−xTa1−xM2xO4 MECs were monoclinic, and the Ti, Zr, and Hf doping elements replaced Y and Ta. The variations in atomic weights and ionic radii led to disturbed atomic arrangements and severe lattice distortions, resulting in improving the phonon scattering and reduced thermal conductivity, with Y1−xTa1−xM2xO4 MECs (x = 0.24) exhibiting the lowest thermal conductivity of 1.23 W·m−1·K−1 at 900°C. The introduction of MO2 increased the configurational entropy and weakened the ionic bonding energy, obtaining high TECs (10.4 × 10−6 K−1 at 1400°C). The reduction in the monoclinic angle β lowered the ferroelastic domain inversion energy barrier. Moreover, microcracks and crack extension toughening endowed Y1−xTa1−xM2xO4 MECs (x = 0.24) with the highest fracture toughness of (4.1 ± 0.5) MPa·m1/2. The simultaneous improvement of the thermal and mechanical properties of the MO2 (M = Ti, Zr, Hf) co-doped YTaO4 MECs can be extended to other materials.
Chinese Journal of Mechanical Engineering•2025•DOI: 10.1186/s10033-025-01276-w
Current topology optimization methods for nonlinear continuum structures often suffer from low computational efficiency and limited applicability to complex nonlinear problems. To address these issues, this paper proposes an improved bi-directional evolutionary structural optimization (BESO) method tailored for maximizing stiffness in nonlinear structures. The optimization program is developed in Python and can be combined with Abaqus software to facilitate finite element analysis (FEA). To accelerate the speed of optimization, a novel adaptive evolutionary ratio (ER) strategy based on the BESO method is introduced, with four distinct adaptive ER functions proposed. The Newton-Raphson method is utilized for iteratively solving nonlinear equilibrium equations, and the sensitivity information for updating design variables is derived using the adjoint method. Additionally, this study extends topology optimization to account for both material nonlinearity and geometric nonlinearity, analyzing the effects of various nonlinearities. A series of comparative studies are conducted using benchmark cases to validate the effectiveness of the proposed method. The results show that the BESO method with adaptive ER significantly improves the optimization efficiency. Compared to the BESO method with a fixed ER, the convergence speed of the four adaptive ER BESO methods is increased by 37.3%, 26.7%, 12% and 18.7%, respectively. Given that Abaqus is a powerful FEA platform, this method has the potential to be extended to large-scale engineering structures and to address more complex optimization problems. This research proposes an improved BESO method with novel adaptive ER, which significantly accelerates the optimization process and enables its application to topology optimization of nonlinear structures.
Journal of Central South University•2025•DOI: 10.1007/s11771-025-6152-7
Considering passenger trains' key role in remote regions, this study employed machine vision technology to monitor five posture parameters of the second car of a conventional passenger train, aiming to investigate the influence of windbreaks and crosswinds along railways on the operating postures of conventional passenger trains. The study found that when passing through the anti-wind tunnel with holes, the amplitudes of posture parameters were smaller than those of other windbreaks, demonstrating the superior performance of this windbreak in maintaining posture stability compared to others. In tunnel sections, larger amplitudes of these parameters were observed for the tail car than the head car, while the opposite occurred in non-tunnel sections. Notably, during tunnel transit, their amplitudes did not increase monotonically with speed but peaked at a specific speed that most adversely affected the operating posture. These conclusions have a great significance for improving operating safety under crosswinds.
Journal of Central South University•2025•DOI: 10.1007/s11771-025-6134-9
Tunnel-induced noise amplification has become a major constraint for high-speed trains. This study employs a 1/10 scale three-coach high-speed train model, using the improved delayed detached eddy simulation (IDDES) method coupled with the perturbed convective wave model to investigate the unsteady flow evolution, aerodynamic noise source distribution, and near-field acoustic characteristics of high-speed trains under open-air and tunnel conditions. The results show that the blocking effect of the tunnel wall enhances flow compression, increases local velocity, and aggravates flow disturbances and pressure fluctuations near the pantograph and tail car. In the tunnel, the total sound source energy reaches 1.14×10¹² N²/s², 5.26 times higher than in open air, with significant increases in the tail car, bogies, and pantograph. Bogie noise concentrates in the 50 to 1000 Hz range, while pantograph noise dominates from 1500 to 2500 Hz. Tunnel conditions further enhance peak distributions in the low and medium frequency bands. Although pressure disturbances on the train surface are mainly dominated by hydrodynamic effects, the radiated acoustic energy of the sound pressure levels on the roof and side surfaces is amplified by 33.3 and 22.6 times, far exceeding hydrodynamic energy amplification factors of 8.6 and 6.3. The study reveals coupled flow and acoustic mechanisms in tunnels, supporting noise reduction design for high-speed trains.
Journal of Central South University•2025•DOI: 10.1007/s11771-026-6170-0
High-speed railway holds a pivotal position in China’s transportation system, closely intertwined with the production and daily lives of people. It serves as a critical carrier for fostering a new development paradigm, supporting high-quality growth, and building a modernized strong nation. Up to 2025, the high-speed railway operating mileage in China has exceeded 50000 km, ranking the first in the world and surpassing the combined total of high-speed railway operating mileage in all other countries. With the rapid advancement of high-speed railway technology, aerodynamics has emerged as a pivotal scientific challenge that limits the enhancements in the safety, efficiency, and comfort of high-speed trains. As train speeds continue to increase, the interactions between trains and the aerodynamic environment become increasingly complex and intense. This complexity gives rise to critical issues such as significant aerodynamic drag, aerodynamic noise, crosswind stability, and intense pressure fluctuations in tunnels, all of which directly impact the overall sustainability and operational performance of high-speed railway systems, becoming one of hot topics in the world. This special issue focuses on the topic of “Aerodynamic Characteristics of Higher-speed Trains”, showcasing cutting-edge research and technological advances in this field. The included studies are organized around four core thematic areas: aerodynamic performance in open air, mechanism and mitigation of aerodynamic noise, crosswind stability, and train/tunnel coupled aerodynamic effects. Specifically, they address topics such as aerodynamic optimization of train shapes, control of transient pressure waves in tunnels, noise reduction strategies, crosswind stability analysis, and innovative applications of computational and experimental methods in train aerodynamics. The research methodologies integrate high-fidelity numerical simulations, advanced model testing, and field measurements, reflecting the interdisciplinary nature of modern aerodynamic research. The contributions in this issue not only deepen the theoretical understanding of high-speed train aerodynamics but also provide practical insights for engineering applications. By exploring novel approaches to aerodynamic design, noise mitigation, and operational safety enhancement, these studies support the development of next-generation high-speed railway systems with improved performance and sustainability. We hope this collection serves as a valuable reference for researchers and engineers engaged in high-speed railway development. It is our aspiration that the findings presented here will stimulate further innovation and contribute to the advancement of safer, more efficient, and environmentally friendly high-speed railway transportation worldwide.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3079-1
Although the existence of glass–glass interfaces (GGIs) enables improved ductility of metallic nanoglasses (NGs), the excess free volumes at GGIs would cause the NGs to have a much-reduced mechanical strength. Herein, entropy-stabilized GGIs have been investigated in Co–Fe–Ni–Zn–P NGs, which have a large entropy of mixing (1.32R, where R is the gas constant) and could be in a new glass phase, different from that of glassy grain interiors. Through quantitatively determining the activation energy of glass transition separately for the GGIs and glassy grain interiors, the excess free volumes at GGIs are found to be reduced in comparison with those in the glassy grain interiors. The thermodynamically stable GGIs could be associated with increasing entropy of mixing in the GGI regions, which stabilizes the atomic structures of GGIs and enhances the glass forming ability of Co–Fe–Ni–Zn–P NGs. The influences of entropy-stabilized GGIs on the mechanical properties of Co–Fe–Ni–Zn–P NGs are further investigated by nanoindentation and creep tests under tensile deformation, demonstrating that there are notable enhancements in the ductility and mechanical strength for Co–Fe–Ni–Zn–P NGs. This work contributes to an in-depth understanding on the GGI phase in NGs and offers an alternative method for strengthening NGs through GGI engineering.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3062-x
The effect of aging precipitation on the stress corrosion cracking (SCC) mechanism of Ni(Fe,Al)-maraging steel was studied through the comparative characterization and analyses of the microstructures and fracture features of solid–solution and peak-aged steels. Aging precipitation exerts a chain of impacts on the deformative compatibility and electrochemical difference between the matrix and other phases or interfaces. The strength of the martensite matrix is enhanced by abundant and evenly dispersed Ni(Fe,Al) precipitates, thereby reducing the possibility of splitting across martensite laths. Meanwhile, the Volta potential difference (VPD) between the matrix and primary NbC particles increases from 11.43 to 18.60 mV. Given that most of the primary NbC particles tend to be distributed along high-angle grain boundaries (HAGBs), anodic dissolution along HAGBs accelerates. Therefore, mechanical and electrochemical factors triggered by aging precipitation are involved in the variation in SCC behavior and mechanism. The SCC susceptibility of the steel increases along with the increasing tendency for intergranular cracking.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-025-3115-9
In order to avoid poor machinability caused by excessive hardness under high-silicon conditions in the traditional free-cutting graphited steel, it is important to develop a suitable silicon-saving, aluminum-containing free-cutting steel. This study investigated the microstructure and graphite precipitation behavior of Fe–0.58C–1.0Al (wt%) steels with varying silicon contents (0.55wt%–2.67wt%) after tempering at different temperatures (680°C, 715°C). The tempering structure and the precipitation behavior of graphite and Fe3C in Fe–0.58C–1.0Al steels were systematically studied by optical microscopy (OM), field emission scanning electron microscopy (FESEM), and electron microprobe analyzer (EPMA). The results showed that, at both tempering temperatures, the microstructure of 0.55wt% Si steel is ferrite + granular Fe3C, and the microstructures of 1.38wt%–2.67wt% Si steels are ferrite + petaloid graphite + granular Fe3C. With increasing Si content from 1.38wt% to 2.67wt% at constant tempering temperature, the number density of graphite particles increases, though their average size decreases. Meanwhile, the number density and average size of Fe3C in experimental steels continuously decrease with the increase of Si content. For 0.55wt% Si steel without graphite precipitation, increasing tempering temperature promotes the accumulation and growth of Fe3C. For 1.38wt%–2.67wt% Si steels with graphite precipitation, higher tempering temperature promotes graphite particles growth while accelerating the decomposition and refinement of Fe3C. Furthermore, compared with the experimental steels containing 0.55wt% Si, 1.38wt% Si, and 2.67wt% Si, the 1.89wt% Si steel exhibits significantly lower hardness. Especially, when tempered at 715°C, Fe–0.58C–1.0Al steel with 1.89wt% Si exhibits enhanced graphitization behavior and reduced hardness, which is nearly HV 20 lower than previously reported Fe–0.55C–2.33Si steel.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3015-4
Recent advancements in electrocatalysis have highlighted the exceptional application value of amorphous electrocatalysts. With their unique atomic configurations, these electrocatalysts exhibit superior catalytic performance compared to that of their crystalline counterparts. Transition metal (TM) amorphous ribbon-shaped electrocatalysts have recently emerged as a new frontier in the catalysis field. Dealloying is widely considered a fascinating method for enhancing the electrocatalyst performance. In this review, we comprehensively examine the principles of water electrolysis, discuss the prevalent methods for fabricating ribbon-configured electrocatalysts, and provide an overview of amorphous alloys. Furthermore, we discuss binary, ternary, and high-entropy amorphous TM-based electrocatalysts, which satisfy the requirements necessary for effective water electrolysis. We also propose strategies to enhance the activity of amorphous TM-based ribbons, including morphology control, defect engineering, composition optimization, and heterostructure creation in different electrolytes. Our focus extends to the latest developments in the design of heterogeneous micro/nanostructures, management of preparation techniques, and synthesis of different compositions. Finally, we address the ongoing challenges and provide a perspective on the future development of broadly applicable, self-supporting TM ribbon-shaped electrocatalysts.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01573-4
Global interest in lithium–sulfur batteries as one of the most promising energy storage technologies has been sparked by their low sulfur cathode cost, high gravimetric, volumetric energy densities, abundant resources, and environmental friendliness. However, their practical application is significantly impeded by several serious issues that arise at the cathode–electrolyte interface, such as interface structure degradation including the uneven deposition of Li2S, unstable cathode–electrolyte interphase (CEI) layer and intermediate polysulfide shuttle effect. Thus, an optimized cathode–electrolyte interface along with optimized electrodes is required for overall improvement. Herein, we comprehensively outline the challenges and corresponding strategies, including electrolyte optimization to create a dense CEI layer, regulating the Li2S deposition pattern, and inhibiting the shuttle effect with regard to the solid–liquid–solid pathway, the transformation from solid–liquid–solid to solid–solid pathway, and solid–solid pathway at the cathode–electrolyte interface. In order to spur more perceptive research and hasten the widespread use of lithium–sulfur batteries, viewpoints on designing a stable interface with a deep comprehension are also put forth.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01590-3
Designing and fabricating a compatible low-reflectivity electromagnetic interference (EMI) shielding/high-temperature resistant infrared stealth material possesses a critical significance in the field of military. Hence, a hierarchical polyimide (PI) nonwoven fabric is fabricated by alkali treatment, in-situ growth of magnetic particles and "self-activated" electroless Ag plating process. Especially, the hierarchical impedance matching can be constructed by systematically assembling Fe3O4/Ag-loaded PI nonwoven fabric (PFA) and pure Ag-coated PI nonwoven fabric (PA), endowing it with an ultralow-reflectivity EMI shielding performance. In addition, thermal insulation of fluffy three-dimensional (3D) space structure in PFA and low infrared emissivity of PA originated from Ag plating bring an excellent infrared stealth performance. More importantly, the strong bonding interaction between Fe3O4, Ag, and PI fiber improves thermal stability in EMI shielding and high-temperature resistant infrared stealth performance. Such excellent comprehensive performance makes it promising for military tents to protect internal equipment from electromagnetic interference stemmed from adjacent equipment and/or enemy, and inhibit external infrared detection.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01496-0
The design and fabrication of high toughness electromagnetic interference (EMI) shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem. Ternary MXene/ANF (aramid nanofibers)–MoS2 composite films with nacre-like layered structure here are fabricated after the introduction of MoS2 into binary MXene/ANF composite system. The introduction of MoS2 fulfills an impressive “kill three birds with one stone” improvement effect: lubrication toughening mechanical performance, reduction in secondary reflection pollution of electromagnetic wave, and improvement in the performance of photothermal conversion. After the introduction of MoS2 into binary MXene/ANF (mass ratio of 50:50), the strain to failure and tensile strength increase from 22.1 ± 1.7% and 105.7 ± 6.4 MPa and to 25.8 ± 0.7% and 167.3 ± 9.1 MPa, respectively. The toughness elevates from 13.0 ± 4.1 to 26.3 ± 0.8 MJ m−3 (~102.3%) simultaneously. And the reflection shielding effectiveness (SER) of MXene/ANF (mass ratio of 50:50) decreases ~10.8%. EMI shielding effectiveness (EMI SE) elevates to 41.0 dB (8.2–12.4 GHz); After the introduction of MoS2 into binary MXene/ANF (mass ratio of 60:40), the strain to failure increases from 18.3 ± 1.9% to 28.1 ± 0.7% (~53.5%), the SER decreases ~22.2%, and the corresponding EMI SE is 43.9 dB. The MoS2 also leads to a more efficient photothermal conversion performance (~45 to ~55 °C). Additionally, MXene/ANF–MoS2 composite films exhibit excellent electric heating performance, quick temperature elevation (15 s), excellent cycle stability (2, 2.5, and 3 V), and long-term stability (2520 s). Combining with excellent mechanical performance with high MXene content, electric heating performance, and photothermal conversion performance, EMI shielding ternary MXene/ANF–MoS2 composite films could be applied in many industrial areas. This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.