Materials最新文献

Machine learning has been widely applied to phase prediction and property evaluation in multi-principal element alloys. In this work, a data-driven machine learning framework is proposed to predict the ultimate tensile strength (UTS) and total elongation (TE) of Fe-Co-Cr-Ni-Mn-Al-Ti multi-principal element alloys (MPEAs), offering a cost-effective route for the design of new MPEAs. A dataset was compiled through an extensive literature survey, and six different machine learning models were benchmarked, from which XGBoost was ultimately selected as the optimal model. The feature set was constructed on the basis of theoretical considerations and experimental data reported in the literature, and SHAP analysis was employed to further elucidate the relative importance of individual features. By imposing constraints on the screened features, two alloys predicted to exhibit superior performance under different heat-treatment conditions were identified and fabricated for experimental validation. The experimental results confirmed the reliability of the model in predicting fracture strength, and the errors observed in ductility prediction were critically examined and discussed. Moreover, the strengthening mechanisms of the designed MPEAs were further explored in terms of microstructural characteristics and lattice distortion effects. The alloy design methodology developed in this study not only provides a theoretical basis for exploring unexplored compositional spaces and processing conditions in multi-principal element alloys, but also offers an effective tool for developing novel alloys that simultaneously achieve high strength and good ductility.

The calculation of the limiting efficiency and structural optimization of solar cells based on the detailed balance principle is systematically investigated in this study. Through modeling and numerical simulations of various cell architectures, the theoretical efficiency limits of these structures under AM1.5G (Air Mass 1.5 Global) spectrum were quantitatively evaluated. Through a comprehensive consideration of the effects of bandgap and composition, the Al_0.03Ga_0.97As/Ge (1.46 eV/0.67 eV) cell configuration was determined to achieve a high theoretical efficiency of 43.0% for two-junction cells while maintaining satisfactory lattice matching. Furthermore, the study proposes that incorporating a Ga_0.96In_0.04As (8.3 nm)/GaAs_0.77P_0.23 (3.3 nm) strain-balanced multiple quantum wells (MQWs) structure enables precise bandgap engineering, modulating the effective bandgap to the optimal middle-cell value of 1.37 eV, as determined by graphical analysis for triple junctions. This approach effectively surpasses the efficiency constraints inherent in conventional bulk-material III-V semiconductor solar cells. The results demonstrate that an optimized triple-junction solar cell with MQWs can theoretically achieve a conversion efficiency of 51.5%. This study provides a reliable theoretical foundation and a feasible technical pathway for the design of high-efficiency solar cells, especially for the emerging MQW-integrated III-V semiconductor tandem cells.

This study presents a systematic investigation of laser surface hardening of 9CrSi tool steel with the aim of establishing the relationships between processing parameters, microstructural evolution, and resulting mechanical and tribological properties under the applied laser conditions. The influence of laser power, modulation frequency, and scanning speed on the hardened layer depth, microstructure, and surface properties was analyzed. Laser treatment produced a martensitic surface layer with varying fractions of retained austenite, while the transition zone consisted of martensite, granular pearlite, and carbide particles. X-ray diffraction identified the presence of α'-Fe, γ-Fe, and Fe₃C phases, with peak broadening associated with increased lattice microstrain induced by rapid self-quenching. The surface microhardness increased from approximately 220 HV_0.1 in the untreated state to 950-1000 HV_0.1 after laser hardening, with hardened layer thicknesses ranging from about 500 to 750 µm depending on the processing regime. Instrumented indentation showed higher elastic modulus values for all hardened conditions. Tribological tests under dry sliding conditions revealed reduced coefficients of friction and more than an order-of-magnitude decrease in wear rate compared with untreated steel. The results provide a parameter-microstructure-performance map for laser-hardened 9CrSi steel, demonstrating how variations in laser processing conditions affect hardened layer characteristics and functional performance.

Urban leaf litter represents an underutilized biomass resource with potential applications in sustainable building materials. This study investigates the suitability of dried, comminuted leaves collected from municipal green areas as a loose-fill thermal insulation material. The material was characterized in terms of thermal conductivity, settlement behavior, fire reaction, resistance to mold growth, water vapor diffusion, hygroscopic sorption, and short-term water absorption. Tests were conducted following relevant DIN and ISO standards, with both untreated and flame-retardant-treated samples examined. Results indicate that the thermal conductivity of leaf-based insulation (λ = 0.041-0.046 W/m·K) is comparable to other bio-based loose-fill materials such as cellulose and wood fiber. Optimal performance was achieved for particles sized 2-16 mm, showing settlement below 1%. All variants, including untreated material, fulfilled the fire resistance requirements of class E, while selected treatments further improved fire resistance. The material exhibited moderate vapor permeability (μ ≈ 4-5), low water absorption, and moisture buffering behavior similar to that of other bio-based insulation materials. Resistance to mold growth was satisfactory under standardized conditions. Overall, the results demonstrate that leaf litter can serve as an effective and environmentally favorable loose-fill insulation material, offering an innovative recycling pathway for urban green waste.

In this study, inverse gas chromatography (IGC) was applied to characterize the key surface physicochemical properties of carbon-mineral composites and to clarify how these properties relate to removal efficiencies of selected antibiotics, with particular emphasis on surface energetic and acid-base characteristics rather than bulk structural parameters. The dispersive component of surface free energy and the acid-base characteristics (K_a/K_b ratio) were determined, alongside measurements of carbon content, while specific surface areas were compared with data reported previously. We found that there is no clear correlation between bulk structural characteristics and the removal efficiency of ciprofloxacin, doxycycline, sulfamethoxazole, and tetracycline. In contrast, the removal of all investigated antibiotics was found to be correlated with the dispersive component of surface free energy and the K_a/K_b ratio. The results suggest that surface energetic parameters and acid-base properties are more closely associated with antibiotic adsorption behavior than basic structural characteristics alone. These findings demonstrate that IGC provides valuable insight into adsorption processes and highlight the importance of surface physicochemical properties for interpreting and predicting the adsorption properties of carbon-mineral composites.

Ceramic matrix composites (CMCs) exhibit excellent high-temperature strength, oxidation resistance, and fracture toughness, making them superior to traditional metals and single-phase ceramics in extreme environments such as aerospace, nuclear energy equipment, and high-temperature protection systems. The mechanical properties of CMCs directly influence the reliability and service life of structures; thus, accurately predicting their mechanical response and service behavior has become a core issue in current research. However, the multi-phase heterogeneity of CMCs leads to highly complex stress distribution and deformation behavior in traditional mechanical property testing, resulting in significant uncertainty in the measurement of key mechanical parameters such as strength and modulus. Additionally, the high manufacturing cost and limited experimental data further constrain material design and performance evaluation based on experimental data. Therefore, the development of effective numerical simulation and mechanical modeling methods is crucial. This paper provides an overview of the research hotspots and future directions in the field of CMCs numerical simulation and mechanical modeling through bibliometric analysis using the CiteSpace software. The analysis reveals that China, the United States, and France are the leading research contributors in this field, with 422, 157, and 71 publications and 6170, 3796, and 2268 citations, respectively. At the institutional level, Nanjing University of Aeronautics and Astronautics (166 publications; 1700 citations), Northwestern Polytechnical University (72; 1282), and the Centre National de la Recherche Scientifique (CNRS) (49; 1657) lead in publication volume and/or citation influence. Current research hotspots focus on finite element modeling, continuum damage mechanics, multiscale modeling, and simulations of high-temperature service behavior. In recent years, emerging research frontiers such as interface debonding mechanism modeling, acoustic emission monitoring and damage correlation, multiphysics coupling simulations, and machine learning-driven predictive modeling reflect the shift in CMCs research, from traditional experimental mechanics and analytical methods to intelligent and predictive modeling.

Acid mine drainages (AMDs) enriched with toxic metals pose a significant environmental risk. Microbial bioremediation offers a sustainable and cost-effective approach for metal removal from AMD. In this study, a wild yeast isolated from the Kavart abandoned mine, identified as Rhodotorula sp., was evaluated for its copper (Cu²⁺) and zinc (Zn²⁺) biosorption ability. Biosorption was strongly pH-dependent. Cu²⁺ and Zn²⁺ removal was most efficient (48.1% or 10.07 mg/g and 35.7% or 6.07 mg/g, respectively) at pH 6. Increasing the biomass to 3 g/L at the same pH enhanced Cu²⁺ removal to 71.5% (26 mg/g). Biosorption kinetic analysis showed an excellent fit to the pseudo-second-order model (R² > 0.99), indicating that the mechanism is chemisorption-dominated. Equilibrium data followed the Langmuir isotherm (R² = 0.93), consistent with monolayer adsorption on homogeneous binding sites. SEM-EDS analysis confirmed Cu²⁺ association with the yeast surface, supporting the ICP-OES results. The results demonstrate the isolate as a promising biosorbent, particularly for Cu²⁺, and highlight its potential application in the remediation of AMD-contaminated waters.

To address the high-carbon emissions associated with the large use of Portland cement (PC) in traditional engineered cementitious composites (ECCs) and the resource constraints on supplementary cementitious materials (SCMs), this study proposes a strategy combining limestone calcined clay cement (LC³) as a PC replacement with the incorporation of hybrid synthetic fibers to develop low-carbon, environmentally friendly ECCs. The fundamental properties of the LC³-ECC were tested, and a sustainability analysis was conducted. The experimental results show that an increase in water-to-binder ratio (W/B) or superplasticizer (SP) dosage significantly enhanced fluidity while reducing the yield stress and plastic viscosity. An LC³-ECC with a W/B of 0.25, 0.45% SP and 2% polyethylene fibers exhibited the best tensile performance, achieving an ultimate tensile strain of 8.40%. In contrast, an increase in polypropylene fiber led to a degradation in crack-resistant properties. In terms of sustainability, replacing the PC with LC³ significantly reduced carbon emissions by 19.1-20.8%, while the cost of the limestone calcined clay cement-polypropylene fiber (LC³-PP) was approximately 50% of that of the limestone calcined clay cement-polyvinyl alcohol fiber (LC³-PVA). Furthermore, an integrated evaluation framework encompassing rheological, mechanical and environmental factors was established using performance radar charts. The dataset on the performance results and the developed assessment framework provide a foundation for optimizing the mixture proportioning of LC³-ECC in practical engineering applications.

Occlusal splints are a type of intraoral appliance that are widely used for the management of temporomandibular disorders and bruxism, yet limited evidence exists regarding the comparative effects of combined aging on conventional and digitally manufactured materials. This in vitro study evaluated the influence of thermal and mechanical aging on the flexural properties of three materials commonly used for the manufacturing of occlusal devices: self-curing poly(methyl methacrylate) (PMMA, control), light-cured urethane dimethacrylate (UDMA)-based resin, and stereolithography (SLA)-printed photopolymer. Seventy-two standardized specimens (n = 24 per material; 64 × 10 × 3.3 mm) were fabricated, then randomly allocated to three groups (n = 8): control, thermocycling (10,000 cycles, 5 °C/55 °C), and combined thermocycling with mechanical loading (1000 cycles). Flexural strength and modulus were determined by three-point bending tests and analyzed using a two-way analysis of variance (ANOVA) with Tukey's post hoc test (α = 0.05). Thermocycling significantly reduced flexural strength in PMMA (65.19 ± 6.68 to 57.94 ± 7.15 MPa) and SLA (67.67 ± 1.54 to 59.37 ± 8.80 MPa) groups (p < 0.05), while UDMA group (45.489 ± 3.905 to 43.123 ± 4.367 MPa) demonstrated no significant changes (p ≥ 0.05). UDMA exhibited substantially and significantly lower flexural properties compared to PMMA and SLA across all conditions (p < 0.0001). Thermal aging slightly compromises the mechanical properties of PMMA and SLA-printed materials, whereas UDMA-based resins exhibit good aging resistance but considerably lower initial values. While UDMA-based resin showed superior aging resistance, its lower baseline mechanical properties may limit its application in high-stress clinical scenarios compared to PMMA and SLA-printed materials. Material selection should consider both initial properties and long-term environmental changes.

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