Search Results (194)

In contemporary engineering applications, deficiencies in dynamic mechanical properties, particularly impact toughness, are the leading cause of fracture incidents. Consequently, inadequate dynamic mechanical properties have emerged as the primary constraint limiting the further commercial application of precipitation-strengthened high-strength aluminum (Al) alloys, exemplified by the 2014 aluminum alloy. Since the dynamic mechanical properties of the 2014 wrought aluminum alloy are fundamentally governed by the decohesion and cracking of coarse second-phase constituent particles, it is necessary to quantify the correlation between microstructure and mechanical properties. Meanwhile, the size and volume fraction of constituent particles are largely dictated by the concentration of main and impurity alloying elements. Experimental results revealed that the volume fraction of coarse constituents increased with increasing Cu, Si, and Fe content, and that tensile ductility and impact toughness decreased following an inverse exponential relationship with the volume fraction of constituents. The aim of this study is to establish a quantitative relation to correlate the characteristics of coarse constituents with the tensile ductility and impact toughness of the 2014 aluminum alloy. A mathematical model was developed by regarding the coarse constituents as ellipsoidal inclusions. Their volume fraction and aspect ratio were considered in the model. Model predictions show broad agreement with experimental data. These properties are more sensitive to the volume fraction when it is low. Conversely, a larger aspect ratio leads to higher ductility and toughness. The sensitivity is also greater at a small aspect ratio. The model further indicates that reducing the volume fraction when it is high yields limited improvement, whereas further reduction at a low volume fraction leads to significant enhancement of ductility and toughness. This study correlates coarse constituent characteristics with tensile ductility and impact toughness quantitatively, and provides a theoretical framework for predicting and optimizing the mechanical properties of 2014 aluminum alloy. Full article

This paper examines a resource-saving technology for ferrosilicon smelting using industrial waste, specifically aluminum slag and aspiration dust from ferroalloy production. A technological approach is proposed based on the preliminary pelletization of finely dispersed aluminum slag to improve the physicochemical properties of the charge materials and ensure their efficient use in the metallurgical process. Pellets were produced by granulation in a disk granulator using a lignosulfonate binder, followed by drying and high-temperature firing in the temperature range of 600–800 °C. Microstructural and energy-dispersive analysis revealed the formation of a stable aluminosilicate matrix, represented predominantly by mullite-like phases, ferrosilicate inclusions, and calcium–magnesium silicates. The formation of these phases contributes to the strengthening of the pellet structure and the formation of intergranular bonds during heat treatment. Experimental ferrosilicon smelting was conducted in a laboratory ore-thermal electric arc furnace. The results demonstrated a stable electrothermal smelting regime, satisfactory charge layer gas permeability, and effective reduction processes. The resulting alloy corresponds to FS-45 ferrosilicon grade with a silicon content of approximately 48%. It was established that aluminum slag-based pellets actively participate in the formation of an aluminosilicate slag system of the SiO₂-Al₂O₃-CaO-MgO type, ensuring favorable slag physicochemical properties and efficient separation of the metallic and slag phases. The proposed approach enables the incorporation of industrial waste into metallurgical production, reducing the environmental impact, and increasing the resource efficiency of silicon ferroalloy production processes. Full article

This study examined the scale of informal metal recycling in the King Sabata Dalindyebo (KSD) Municipality and evaluated its socioeconomic and environmental impacts through a circular economy lens. While formal recycling programs have received research attention, informal recycling systems have been less examined despite their critical contribution. A mixed-methods approach was employed, combining quantitative surveys and material measurements with qualitative field observations. Data were collected through focus groups and surveys administered to 48 active recyclers operating along the N2 and R61 highways, supported by systematic field observations and quantification of all recovered materials. The results showed that steel and aluminum were the most recovered metals at 41.7% and 20.8%. Recyclers collected an average of 15.3 kg/day (SD = 4.2) during periods of high material availability and accessibility and the materials are close to market points. The study underscores the socioeconomic and environmental impacts of informal recycling within the circular economy framework, with most participants (85.42%) indicating that recycling was a significant livelihood while 74% cited difficulty transporting bulky materials, often manually. Therefore, the study emphasizes that informal recyclers play a vital role in sustaining the local economy by offering key waste management and resource recovery services. Acknowledge of these informal systems will contribute to a more inclusive understanding of waste management in developing contexts. Full article

Aluminum alloying was considered difficult at excessively high aluminum mass fractions. For high-aluminum steel subjected to aluminum alloying under vacuum conditions, a positive trend was observed between the aluminum content and the aluminum yield. As the aluminum content increased from 5 to 5.5, the aluminum yield rose from 89.56% to 95.76%. Theoretical calculations were performed to determine that the saturated vapor pressures of pure aluminum were 267 Pa, 440 Pa, and 704 Pa at 1600 °C, 1650 °C, and 1700 °C, respectively. In consideration of aluminum volatility and temperature effects, the maximum aluminum yield was obtained at 1600 °C under 267 Pa. During smelting in a vacuum induction furnace, fine inclusions (1–5 μm) were counted for 82.4% of the total inclusions, whereas large inclusions (>20 μm) were recorded at only 0.98%. This phenomenon was attributed to the fact that the rising time of small-sized inclusions was 2500 times longer than that of large ones. Full article

Laser powder bed fusion (LPBF) of aluminum matrix tribological composites holds high potential for advanced bearing applications, yet its widespread implementation is often constrained by high porosity and severe residual stresses. In this work, the influence of hot pressing (HP) temperature (100–400 °C) on the microstructure, substructural evolution, mechanical properties, and fracture mechanisms of the LPBF Al-10Sn-10Pb alloy was investigated to achieve simultaneous densification and matrix optimization. Processing was carried out at 300 MPa with a 30 min holding time. It was established that at temperatures >200 °C, near-full consolidation is achieved through liquid-assisted pore closure. Increasing the temperature leads to the coarsening of Sn and Pb inclusions and the disruption of the initial dispersed network of soft phases. Williamson–Hall analysis revealed a transition from dislocation accumulation at 100 °C (~15 × 10¹³ m⁻²) to dynamic recovery at 200 °C, followed by matrix recrystallization at higher temperatures. A combination of strength (up to 127 MPa) and ductility (~11%) is realized at 200 °C due to the synergy between remaining substructural strengthening and pore healing. At 300–400 °C, the strength decreases to 108–113 MPa with a concomitant increase in ductility to 34–44%. A shift in fracture mechanisms from quasi-brittle to ductile is shown; at 400 °C, the development of intergranular fracture associated with the influence of liquid phases is possible. Full article

While aluminum (Al) continues to be a cornerstone for microelectronic interconnect technologies, its chronic tendency toward hillock growth and thermal instability necessitates a transition toward high-performance nanostructured material architectures. This research tackles these reliability bottlenecks by achieving a molecular-level integration of graphene nanoplatelets (GNPs) within Al matrices, a strategy designed to fortify structural resilience. Adopting a green chemistry approach, we synthesized Al-GNP (0.25 vol.%) composite thin films through Pulsed Laser Deposition (PLD) using precursors derived from recycled aluminum. A major obstacle—the formation of the deleterious Al₄C₃ intermetallic phase—was effectively suppressed by ensuring a homogeneous supramolecular dispersion via a specialized dual protocol (ultrasonication and magnetic stirring) during the powder metallurgy stage. Comprehensive physicochemical characterization, utilizing HR-TEM and XRD, verified the structural integrity of the multilayer GNPs (d-spacing = 4.6 Å). Furthermore, surface metrology analysis uncovered a radical shift in growth kinetics: whereas pure Al grew via a “spiky” Volmer-Weber mechanism (Sku = 31.17), the carbon-based inclusion stabilized the film evolution, tempering the kurtosis to Sku = 7.74. Analytical cross-sectional EDS confirmed both stoichiometric fidelity and the achievement of void-free Si/Pt/Al-GNP interfaces. These outcomes prove that a precise nanoscale tailoring of surface morphology via carbonaceous reinforcements significantly bolsters microstructural stamina. Consequently, these PLD-deposited composites emerge as sustainable, cutting-edge candidates for the next generation of microelectronic packaging and interfacial chemistry applications. Full article

Aluminum multifunctional housings can enhance circularity in electronics by replacing polymer enclosures while integrating heat sinking and electronic functions via laser direct structuring (LDS). Within the ALU4CED concept, we applied an IR-compatible LDS lacquer on aluminum, formed conductive tracks by electroless Cu/Ni/Au metallization, assembled components, and assessed end-of-life recyclability. Controlled remelting trials compared three disassembly levels: complete housings with PCBs and components, housings without PCBs, and housings with only integrated tracks. Metal yield rose from 81.4% for complete assemblies to 93.2% after PCB removal, while leaving integrated LDS tracks did not measurably penalize recovery. Only the complete electronics variant showed critical contamination (Cu = 1.64 wt.% vs. 0.25 wt.% limit for EN AC 4343); after PCB removal, composition remained close to the reference and major elements (Si, Mg, Fe) stayed within specification. Prefil testing indicated very low total inclusion content (0.006/0.001/0.002 mm²·kg⁻¹), confirming high melt cleanliness despite coatings. Following remelting → billet casting → extrusion, tensile properties (Rm ≈ 120–123 MPa, Rp0.2 ≈ 59–61 MPa, A ≈ 29–33%) were comparable to the reference profile. These results demonstrate the technological feasibility of closed-loop recycling for LDS functionalized aluminum housings and inform clear Design-for-Recycling guidance: design for rapid PCB removal, allow LDS layers to remain during melting, and maintain compatibility with the 4343 family to enable efficient internal recycling. Full article

Based on the thermodynamic design of metallurgical reduction, this paper investigates the thermodynamic principles and reaction regulation mechanism of aluminothermic self-propagating reduction for the in situ synthesis of a Ti₄₅Al₈Nb (at%) titanium–aluminum–niobium alloy. The influence of the aluminum distribution coefficient (ADC) on the self-propagating reaction process was verified via high-temperature thermal state experiments. The results show that the thermodynamically predicted trends of phase composition and alloy composition are consistent with the experimental results, with only a ~20% lateral offset in the ADC. When the ADC is set to 0.8, the mass fractions of Ti, Al, Nb, O, and N in the alloy are 51.8%, 29.5%, 17.4%, 1.2%, and 0.0016%, respectively, with a homogeneous microstructure and inclusion size no larger than 8 µm. The alloy presents a typical coarse-grained structure, where 83.1% of the total grain boundary length is low-angle grain boundaries, and the <111> orientation is dominant. A low-energy coherent interface is formed between the Ti-enriched and Nb-enriched regions by TiAl, TiAl₃ and Al₃Nb phases, which enhances the structural stability of the alloy. Full article

Phase formation characteristics during the thermochemical reduction of metals from natural coltan using aluminum and calcium–aluminum alloy at 1400–1450 °C were investigated to develop methods for extracting niobium and tantalum from rare metal raw materials. The studied coltan sample consists of a columbite–tantalite solid solution with the composition (Mn,Fe)(Nb,Ta)₂O₆, cassiterite Sn_0.9O₂, tapiolite (Ta,Nb)₂(Mn,Fe)O₆, and calcioolivine Ca₂SiO₄. This study established that the choice of reducing agent determines the sequence of oxide phase transformations. During the aluminothermic process, orthorhombic columbite–tantalite is completely reduced, while tetragonal tapiolite persists even at 1400 °C. The use of a calcium–aluminum alloy containing 69.4 wt.% Ca results in a reversal of this trend: tapiolite is reduced at the early stages (800–1250 °C) through an intermediate (Ta,Nb)O₂ phase, whereas the columbite–tantalite solid solution remains up to 1250 °C. Calcium, having a high affinity for oxygen, forms intermediate perovskite-type oxide phases that act as diffusion barriers, limiting the access of the reducing agent to residual mineral inclusions (mainly Nb-Ta minerals of the orthorhombic crystal system). A temperature rise to 1450 °C initiates the redistribution of oxide components: the content of CaNbO₃ decreases, the Ca₂(Nb,Ta)AlO₆ phase disappears, and its components are involved in the formation of Ca(Nb,Ta)_0.25MnO_2.74 and Ca₄Nb₂O₉. Diffusion constraints are reduced, and the residual columbite–tantalite solid solution is reduced, as confirmed by its complete absence in the products at 1450 °C. In the metallic phase, solid solutions of tantalum and niobium, Ta-Nb-Sn intermetallic compounds (Ta,Nb)₃Sn, titanium aluminide, and ferroalloys with an increased (Ta,Nb)/(Fe,Mn) ratio are formed. The phase transformations elucidated during metallothermic reduction of coltan using different reducing agents, together with the formation of metallic and intermetallic phases, establish a scientific foundation for the development of advanced rare metal extraction processes. Full article

Advances in dental material science over recent decades have significantly improved the mechanical, physical, esthetic, and adhesive properties of restorative systems. As clinical performance and durability have reached high standards, research has progressively shifted from purely mechanical replacement toward the development of bioactive materials capable of interacting beneficially with biological tissues. Rather than functioning solely as passive restoratives, contemporary materials are increasingly designed to contribute to disease prevention and tissue repair. Bioactive functionality encompasses both bioprotective and biopromotive effects, including antimicrobial activity, reinforcement of the dental substrate, promotion of remineralization, modulation of inflammatory responses, and stimulation of regenerative pathways. In this context, the surface pre-reacted glass ionomer (S-PRG) particle has emerged as a multifunctional bioactive technology. Its unique three-layer structure enables sustained release of multiple ions, fluoride, strontium, boron, sodium, silicate, and aluminum, associated with mineralization, biofilm inhibition, inflammatory regulation, and activation of cellular signaling pathways. An integrative review was conducted through a literature search in PubMed, SciELO and Scopus using the descriptors “Surface-reaction-type prereacted glass ionomer” and “S-PRG.” Experimental studies evaluating antimicrobial, anti-inflammatory, remineralizing, cellular, or regenerative effects of S-PRG-containing materials were considered eligible. A total of 49 studies met the inclusion criteria and were analyzed through descriptive synthesis. The available evidence indicates that the biological activity of S-PRG-containing materials extends beyond caries prevention, including modulation of inflammatory responses, enhancement of mineralization processes, and stimulation of cellular pathways related to tissue repair. These findings highlight the potential of S-PRG technology as a promising strategy for the development of restorative materials with regenerative and preventive properties. Full article

Coagulation is a core technology for treating micro-polluted water containing algae and phosphorus. The development of a new coagulant is crucial for reducing operational costs in water treatment plants and similar enterprises. However, compared with traditional chemical coagulants, mineral-based materials have received relatively less attention in the development of high-efficiency coagulants, and their application potential remains to be fully explored, while traditional coagulants such as polyaluminum chloride (PAC) still dominate the market. This study investigated the effectiveness of a polysilicate aluminum ferric coagulant (PSAC) derived from volcanic rock. The influence of various parameters during synthesis and application on PSAC performance was examined, including NaOH dosage, polymerization temperature, silicic acid content, aging time, water environment pH, water quality type, and coagulant dosage. Performance was evaluated based on the removal efficiency of turbidity, UV₂₅₄, algae density, and total phosphorus. The results showed that the optimal preparation conditions for PSAC are: NaOH dosage of 8 mL, polymerization temperature of 60 °C, inclusion of silicic acid, aging for 72 h, and a pH range of 7–8. Under these conditions, the coagulant demonstrated high removal efficiency for the targeted pollutants. At a PSAC dosage of 80 mg/L, the removal rates for UV₂₅₄, algae, and total phosphorus were 90.2%, 99.2%, and 96.4%, respectively, with stable coagulation performance observed across different water qualities. Overall, PSAC exhibits good removal efficiency for UV₂₅₄, total phosphorus, and algae, indicating its great potential as a coagulant for water and wastewater treatment. Full article

The work studied the effect of high-temperature annealing on the phase composition, microstructure, and mechanical properties of an AlSn10Pb10 vol.% alloy obtained by laser powder bed fusion (LPBF). For this purpose, a series of anneals was carried out in the temperature range of 200–500 °C with a duration of 30 min. Using X-ray diffraction, it was determined that the annealed samples had a three-phase structure consisting of Al, β-Sn, and α-Pb phases, with a gradual decrease in their lattice elastic strain and dislocation density as the heating temperature increased. Analysis of the obtained SEM images revealed that these changes were accompanied by the coarsening of Sn and Pb inclusions and growth of the pure aluminum areas. As a result of the described structural changes with increasing annealing temperature, the ultimate compressive strength of the alloy monotonically decreased from 108 MPa (in the as-built state) to 75 MPa after annealing at 500 °C. The alloy’s ductility (strain at peak stress) also improved and reached a maximum of 26% after annealing at 400 °C. Compression test results showed that the optimal combination of ductility and strength of the LPBF-processed AlSn10Pb10 alloy was observed after annealing at 400 °C. Full article

Background: Saliva has been identified as a valuable diagnostic biofluid due to its non-invasive collection and its capacity to reflect oral and systemic biological processes. Advances in analytical chemistry, biosensing technologies, and artificial intelligence (AI)-assisted data integration have broadened the applications of salivary diagnostics. Among salivary exposome components, heavy metals such as lead, cadmium, mercury, nickel, chromium, arsenic, and aluminum serve as biologically and clinically relevant indicators of environmental exposure, toxic burden, and disease-associated molecular disorders. Methods: This structured review integrates clinical, experimental, and translational studies published between January 2020 and January 2026 that examined salivary heavy metal profiling in relation to oral health. Evidence was identified using systematic searches of PubMed/MEDLINE and supplementary sources. Studies were qualitatively assessed regarding analytical methodologies, reported concentration ranges, biological mechanisms, disease associations, and the development of digital and AI-assisted diagnostic applications. Results: Thirteen human clinical studies and six animal or in vivo investigations met the inclusion criteria. Across these studies, altered salivary metal profiles were linked to oxidative stress, inflammatory signaling, immune dysregulation, microbiome disturbances, and genotoxic markers relevant to periodontal disease, oral mucosal pathology, and the risk of oral squamous cell carcinoma. Inductively coupled plasma mass spectrometry was the predominant analytical platform, while emerging biosensor technologies showed potential for rapid detection and monitoring. Digital and AI-based approaches were identified as promising tools for integrating metallomic data with clinical and molecular biomarkers to support exposure-informed risk stratification. Conclusions: Salivary heavy metal profiling represents a biologically informative, non-invasive method for exposure-aware risk assessment in oral health. Although current clinical translation is limited by methodological variability, small cohort sizes, and the lack of standardized reference ranges, integration with digital biosensing platforms and explainable AI frameworks might facilitate scalable, precision-oriented salivary diagnostics. Full article

The planned inclusion of the steel and electrolytic aluminum sectors into China’s Carbon Emission Allowance (CEA) market—initially limited to thermal power since 2021—will expand its coverage to approximately 70% of national carbon emissions, significantly influencing carbon pricing. This study employs a Variational Mode Decomposition–Support Vector Regression (VMD-SVR) model to forecast carbon price fluctuations under three post-expansion scenarios. The results indicate that, in addition to quota allocations, factors such as sectoral emission scales, the CSI 300 Power Index, and the Shanghai Energy Price Index substantially affect price trends. While market expansion induces a short-term price increase, it also stabilizes prices by reducing volatility. Furthermore, different quota allocation methods yield distinct outcomes: equal allocation facilitates a smoother market transition, whereas benchmarking provides stronger incentives for emissions reductions. Full article

This study investigates the application of phononic crystal plates for automotive vibration and noise attenuation through a combined material–structure design approach. Four materials—aluminum, lead, epoxy resin, and plexiglass—were selected to construct a composite plate with a low-density matrix and high-density metallic inclusions. Finite element modeling in COMSOL Multiphysics identified organic glass–lead as the optimal configuration, balancing wide bandgap performance with low-frequency characteristics and lightweight requirements. Parametric analysis demonstrated that rectangular inclusions provide the widest bandgap under equal area conditions, and increasing their volume fraction shifts the bandgap to lower frequencies while broadening its width. The study verifies the reliability of the finite element method (FEM) and further explains the formation mechanism of the bandgap. This study proposes a phononic crystal plate structure with optimal performance: a rectangular phononic crystal plate with a length of A = 20 mm and a height of B = 10 mm serves as the matrix, and four identical rectangular inclusions each with an area of S = 16 mm² are embedded in it. The matrix material is organic glass, while the material of the inclusions is lead. The resulting optimized structure exhibits a complete Lamb wave bandgap from 6.29 to 22.03 kHz, with strong elastic wave attenuation extending over 6.00–30.00 kHz. Acoustically, it achieves sound transmission loss (STL) exceeding 130 dB within 5.85–27.91 kHz, peaking at 143.99 dB. These results verify the structure’s dual functionality in simultaneous vibration isolation and sound attenuation within the same frequency range, demonstrating the potential of phononic crystal plates for targeted noise and vibration control in automotive engines and rotating machinery. Full article