Search Results (101)

Introducing and compacting lignocellulosic biomass in aluminum structures, though recommendable in terms of higher sustainability, the potential use of agro-waste and significant weight reduction, still represents a challenge. This is due to the variability of biomass performance and to its limited compatibility with the metal. Another question may concern possible moisture penetration in the structure, which may reduce environmental resistance and result in local degradation, such as wear or even corrosion. Despite these limitations, this hybridization enjoys increasing success. Two forms are possibly available for this: introduction into metal matrix composites (MMCs), normally in the form of char from biomass combustion, or laminate reinforcement as the core for fiber metal laminates (FMLs). These two cases are treated alongside each other in this review, first because they may represent two combined options for recycling the same biomass into high-profile structures, aimed primarily at the aerospace industry. Moreover, as discussed above, the effect on the aluminum alloy can be compared and the forces to which they are subjected might be of a similar type, most particularly in terms of their hardness and impact. Both cases considered, MMCs and FMLs involved over time many lignocellulosic residues, starting from the most classical bast species, i.e., flax, hemp, sisal, kenaf, etc., and extending also to less diffuse ones, especially in view of the introduction of biomass as secondary, or residual, raw materials. Full article

Pyrometallurgical recycling of lithium-ion batteries presents distinct advantages including streamlined processing, simplified pretreatment requirements, and high throughput capacity. However, its industrial implementation faces challenges associated with high energy demands and lithium loss into slag phases. This investigation develops an integrated reduction smelting–chloridizing volatilization process for the comprehensive recovery of strategic metals (Li, Mn, Cu, Co, Ni) from spent ternary lithium-ion batteries; calcium chloride was selected as the chlorinating agent for this purpose. Thermodynamic analysis was performed to understand the phase evolution during reduction smelting and to design an appropriate slag composition. Preliminary experiments compared carbon and aluminum powder as reducing agents to identify optimal operational parameters: a smelting temperature of 1450 °C, 2.5 times theoretical CaCl₂ dosage, and duration of 120 min. The process achieved effective element partitioning with lithium and manganese volatilizing as chloride species, while transition metals (Cu, Ni, Co) were concentrated into an alloy phase. Process validation in an induction furnace with N₂-O₂ top blowing demonstrated enhanced recovery efficiency through optimized oxygen supplementation (four times the theoretical oxygen requirement). The recovery rates of Li, Mn, Cu, Co, and Ni reached 94.1%, 93.5%, 97.6%, 94.4%, and 96.4%, respectively. This synergistic approach establishes an energy-efficient pathway for simultaneous multi-metal recovery, demonstrating industrial viability for large-scale lithium-ion battery recycling through minimized processing steps and maximized resource utilization. Full article

Recycled aluminum–silicon alloys provide significant environmental benefits by reducing the consumption of raw materials and lowering carbon emissions. However, their industrial application is limited by the presence of iron-based intermetallic compounds and the insufficient investigation in the literature regarding their effects on mechanical behavior. This study focuses on a recycled EN 42000 alloy, comprising 95% recycled aluminum, with a focus on the effect of its elevated iron content (0.447 wt%) on aging behavior and mechanical performance. Laboratory-scale specimens were produced through gravity die casting and subjected to T6 heat treatment, consisting of solution, quenching, and artificial aging from 160 °C to 190 °C for up to 8 h. To investigate overaging, analyses were conducted at 160 °C and 170 °C for durations up to 184 h. Tensile tests were conducted on specimens aged under the most promising conditions. Based on innovative quality indices and predictive modeling, aging at 160 °C for 4.5 h was identified as the optimal condition, providing a well-balanced combination of strength and ductility (YS = 258 MPa, UTS = 313 MPa, and e% = 3.9%). Mechanical behavior was also assessed through microstructural and fractographic analyses, highlighting the capability of EN 42000 to achieve properties suitable for high-performance automotive components. Full article

This study signifies the development and characterization of a composite material with a metallic matrix of aluminum reinforced with a steel mesh, utilizing centrifugal casting technology. An evaluation was conducted to ascertain the influence of the formulation process and the presence of the insert on the mechanical behavior with regard to tensile strength. The aluminum matrix was obtained from commercial and scrap alloys, elaborated by advanced methods of degassing and chemical modification. Meanwhile, the steel mesh reinforcement was cleaned, copper plated, and preheated to optimize wetting and, consequently, adhesion. The structural characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analyses (EDX), which highlighted a well-defined interface and uniform copper distribution. The composite was produced by means of horizontal-axis centrifugal casting in a fiberglass mold, followed by cold rolling to obtain flat specimens. A total of eight tensile specimens were examined, with measured ultimate tensile strengths ranging from 78.5 to 119.8 (MPa). A thorough examination of the fractured specimens revealed a brittle fracture mechanism, devoid of substantial plastic deformation. The onset of failures was frequently observed at the interface between the aluminum matrix and the steel mesh. The use of SEM and EDX investigations led to the confirmation of the uniformity of the copper coating and the absence of significant porosity or interfacial defects. A bimodal distribution of tensile strength values was observed, a phenomenon that is likely attributable to variations in mesh positioning and local differences in solidification. A correlation was established between the experimental results and an analytical polynomial model, thereby confirming a reasonable fit. In sum, the present study provides a substantial foundation for the development of metal matrix composites with enhanced performance, specifically designed for challenging structural applications. This method also demonstrates potential for recycling aluminum scrap into high-performance composites with controlled microstructure and mechanical integrity. Full article

Aluminum recycling is a key pillar of sustainable metallurgy, protecting natural resources, reducing energy consumption by up to 15 times compared with primary aluminum production and significantly lowering the demand for raw materials. This article presents a comprehensive study on the impact of barbotage refining time and recycled scrap content on EN AC-46000 (AlSi9Cu3) alloy, covering the entire process from the initial ingot to the final casting, contributing to a circular economy. The input material consisted of varying proportions of pure ingots and scrap, with scrap content set at 80%, 70%, and 60%, respectively. Each material batch underwent different refining times: 0, 7, 9, and 15 min. Microstructural studies were conducted using light and scanning electron microscopy techniques. Additionally, pore distribution and their proportions within the material volume were analyzed using X-ray computed tomography. This study also examined hardness and gas content relative to the refining time. It was demonstrated that the refining process promoted microstructural homogenization and reduced porosity throughout the production process. Furthermore, extending the refining time positively impacted the reduction of porosity in thin-walled castings and lowered the gas emission level from the alloy, resulting in improved final product quality. Full article

The increasing restriction of lead in industrial alloys, particularly in copper–zinc-based materials such as CuZn40Pb2, necessitates the development of environmentally safer alternatives. ZnAl15Cu1Mg (ZEP1510), a zinc-based wrought alloy composed of 15% aluminum, 1% copper, 0.03% magnesium, with the remainder being zinc, has emerged as a promising candidate for lead-free applications due to its favorable forming characteristics and corrosion resistance. This study investigates the performance of ZEP1510 compared to conventional leaded copper alloys and galvanized steel. Corrosion behavior was evaluated using neutral salt spray testing, cyclic climate chamber exposure, and electrochemical potential analysis in chloride- and sulfate-containing environments. ZEP1510 exhibited corrosion resistance comparable to brass and significantly better performance than galvanized steel in neutral and humid atmospheres. Combined with its low processing temperature and high recyclability, ZEP1510 presents itself as a viable and sustainable alternative to brass with lead for applications in sanitary, automotive, and electrical engineering industries. Full article

One of the key problems in the billet and shaped casting of aluminum alloys is the presence of various undesirable inclusions and impurities in the melt, which can serve as stress concentrators in the finished product, as well as dissolved hydrogen, which contributes to the formation of porosity. The interaction of aluminum with other gases produced by the combustion of fuel particles, oil, and paint materials brought into the furnace together with charge and scrap increases the amount of nitrides, oxides, carbides, and sulfides in the melt. Flux treatment is widely used as protection of aluminum alloys from oxidation and removal of impurities. The present paper reports the data of a comparative analysis of five widely used flux compositions based on sodium, potassium, and magnesium chlorides. The study covers the following aspects: chemical composition, moisture content, melting temperature and melting range, particle size distribution, and refining ability as measured by the change in Na, Ca, and H₂ content after melt treatment. Full article

With the increasing demand for premium-quality aluminum alloy castings that can be used as safety-critical structural components, as well as the rising urge to utilize sustainable materials during the manufacturing process, novel technologies need to be developed and implemented during the treatment of liquid alloys. Impurity and alloying elements accumulate in recycled aluminum alloys, which frequently results in the formation of coarse intermetallic compound (IMC) particles in the microstructure that have a detrimental effect on the ductility of cast products. One successful approach to alleviate this negative effect relies on affecting the phase selection and refinement of IMC phases. A growing body of literature has shown that the crystallization process of IMCs is affected by the native oxide phases present in the liquid alloys. It has also been demonstrated that by appropriate technologies, harmful oxide inclusion (like oxide bifilms) can be transformed into small-sized oxide particles that can be dispersed throughout the liquid alloy to serve as heterogeneous nucleation sites for different phases. In this way, the adverse effects of oxide inclusions and IMCs are simultaneously mitigated. This contribution aims to review the recent progress of experimental and theoretical work related to intermetallic particle refinement by oxide phases. Emerging technological solutions capable of refining intermetallics through transforming harmful oxide inclusions into numerous, well-dispersed heterogeneous nucleation sites are comprehensively reviewed. Besides analyzing the current state of these techniques, this discussion evaluates their future implications and the potential challenges that may arise in their application and development. Full article

This study investigates the effects of graphite particle reinforcement on the mechanical and tribological properties of aluminum alloy AA6061 composites produced via hot press forging (HPF), a direct recycling method for aluminum chips. Graphite content varied from 2.5% to 12.5%, with the Al6061-7.5%Gr composite achieving the highest tensile strength (102.36 MPa) and yield strength (87.07 MPa). Hardness peaked at 24.73 HV with 5% graphite. Tribological tests showed improved wear resistance at higher graphite levels, with the Al6061-12.5%Gr composite exhibiting the lowest wear rate (0.00033 mm³/N·m). These findings highlight HPF’s potential for sustainable fabrication of high-performance aluminum composites. Full article

This study investigated the effect of the recycling process on the microstructure, hardness, and precipitation kinetics of strengthening phases in the 2017A aluminum alloy. Light microscopy (LM) and X-ray diffraction (XRD) analyses revealed that the as-cast microstructure of the recycled 2017A alloy contained intermetallic phases, including θ-Al₂Cu, β-Mg₂Si, Al₇Cu₂Fe, Q-Al₄Cu₂Mg₈Si₇, and α-Al₁₅(FeMn)₃(SiCu)₂, and was comparable to that of the primary alloy, confirming its potential for high-performance applications. During solution heat treatment, most of the primary intermetallic precipitates, such as Al₂Cu, Mg₂Si, and Q-Al₄Cu₂Mg₈Si₇, dissolved into the solid Al matrix. DSC analysis of the solution-treated alloy established the precipitation sequence as follows: α-ss → GP/GPB zones → θ″ → θ′/Q′ → θ-Al₂Cu/Q-Al₄Cu₂Mg₈Si₇. The combined results from XRD, LM, TEM, and DSC confirmed that both θ and Q phases contributed to strengthening, with θ″ and θ′ phases playing a dominant role. Brinell hardness measurements during natural and artificial aging revealed that hardness increased with aging time, reaching a maximum value of 150.5 HB after ~22 h of artificial aging at 175 °C. The precipitation kinetics of the recycled 2017A alloy was studied via DSC measurements over a temperature range of ~25 to 550 °C, at heating rates of 5, 10, 15, 20, and 25 °C/min. The peak temperatures of clusters, GP zones, and hardening phases (θ′, θ″, θ, and Q) were analyzed to calculate the activation energy using mathematical models (Kissinger, Ozawa, and Boswell). The obtained values of activation energies of discontinuous precipitation were comparable across methods, with values for the θ″ phase of 89.94 kJ·mol⁻¹ (Kissinger), 98.7 kJ·mol⁻¹ (Ozawa), and 94.33 kJ·mol⁻¹ (Boswell), while for the θ′ phase, they were 72.5 kJ·mol⁻¹ (Kissinger), 81.9 kJ·mol⁻¹ (Ozawa), and 77.2 kJ·mol⁻¹ (Boswell). These findings highlighted the feasibility of using recycled 2017A aluminum alloy for structural applications requiring high strength and durability. Full article

Miniaturized components for enhanced integrated functionality or thin sheets for lightweight applications often consist of face-centered cubic metals. They exhibit good strength, corrosion resistance, formability and recyclability. Microfabrication technologies, however, may introduce cold work or detrimental heat-induced lattice defects into the material, with consequences for the mechanical properties. Austenitic stainless steels (1.4310, 1.4301) and aluminum alloys (EN AW-5005-H24, EN AW-6082-T6) were selected for this study. The influence of pulsed fiber laser cutting, microwaterjet cutting, and annealing on the strain–stress behavior was investigated. The micro-tensile test setup comprised a flex-structure force sensor, a laser extensometer, and a dedicated sample holder. Fiber laser cut 1.4310 samples exhibited early failure at low fracture strain in narrow shear band zones. The shear band zones were detectable on the sample surface, in the laser extensometer images, in the horizontal sections of the stress–strain curves, and in the microstructure. Inside the shear band zones, grains were strongly elongated and exhibited numerous parallel planar defects. Heat-induced chromium carbides, in combination with low stacking fault energy (SFE) and elevated carbon content, favored shear band zone formation in 1.4310. In contrast, microwaterjet cut high SFE materials EN AW-5005-H24 and EN AW-6082-T6, as well as low-carbon austenitic stainless steel 1.4301, exhibited uniform plastic deformation. Full article

Increasing the share of circulating scrap in produced castings is not only due to optimizing production costs, but also the need to protect the environment realized by reducing production energy intensity, generating less waste, mitigating greenhouse gas emissions, and consuming fewer natural resources. However, this is associated with maintaining the required properties of castings and considering the impact of impurities on the formation of the structure of aluminum alloys. This research concerns the AlSi10MnMg alloy, which introduces 50 to 75% (every 5%) of circulating scrap. This alloy is one of the most commonly used for producing gravity and pressure die-castings (HPDC), including engine parts and transport structural elements. Based on microscopic research, it was found that the increase in scrap content causes an increase in the share of iron, which results in pre-eutectic (from about 0.45 wt.% to 0.7 wt.% Fe) or even primary crystallization of iron phases (over 0.7 wt.% Fe), mainly the plate–needle phase β-Al₅FeSi. Its unfavorable morphology and size cause the formation of numerous shrinkage porosity areas, which has an impact on the reduction in mechanical properties (reduction in UTS and YS by approx. 16% and elongation by approx. 18%, compared to the AlSi10MnMg alloy with 50% scrap content). It was found that the increase in the share of recycled scrap (from 50 to 75%) can be used only when the manganese content is increased. Its effect is to change the morphology of the β-Al₅FeSi phase into α-Al₁₅(Fe,Mn)₃Si₂, whose crystallization occurs in the temperature range of 540 to 555 °C and increases slightly with increasing manganese addition. It is essential to consider the appropriate value of the Mn/Fe quotient, which should be about 1/2, because a higher value may cause the formation of a sludge factor. This work aimed to determine the limiting iron content (contained in the scrap) at which the sequence of the β-Al₅FeSi phase release (pre-eutectic or primary crystallization) changes. This sequence mainly affects the form of morphology, the dimensions of the β-Fe phase, and the proportion of shrinkage porosity. Full article

The manufacturing sector is a major contributor to global energy consumption and greenhouse gas emissions, positioning sustainability as a critical priority. Aluminum, valued for its lightweight and recyclable properties, plays a vital role in advancing energy-efficient solutions across transportation and aerospace industries. The processing of aluminum alloys through laser-based powder bed fusion of metals (PBF-LB/M), a cutting-edge additive manufacturing technology, enhances sustainability by optimizing material usage and enabling innovative lightweight designs. Based on the published literature, the present study analyzed the ecological impacts of aluminum PBF-LB/M manufacturing through life cycle assessment, circular economy principles, and eco-design strategies, identifying opportunities to reduce environmental footprints. The study also stated the critical challenges, such as the high energy demands of the aluminum PBF-LB/M process and its scalability limitations. Potential sustainable solutions were discussed starting from powder production techniques, as well as optimized processes and post-processing strategies. By adopting an interdisciplinary approach, this research highlighted the pivotal role of PBFed aluminum alloys in achieving sustainable manufacturing goals. It provided actionable insights to drive innovation and resilience in industrial applications, offering a roadmap for balancing environmental stewardship with the demands of high-performance standards. Full article

The use of lightweight components in automobiles started a new chapter in the automotive sector due to the renewable energy and sustainability increasing the overall efficiency of vehicles. As vehicle weight is directly linked to energy consumption, reducing mass through advanced materials can significantly decrease energy usage and emissions over the vehicle’s lifetime. This present study aims to conduct a preliminary life cycle assessment (LCA) of a prototype battery pack manufactured using pultruded composite materials with a volume fraction of 50% glass fibers and a volume fraction of 50% nylon 6 (PA6) matrix by quantifying the CO₂ emissions and cumulative energy demand (CED) associated with each stage of the battery pack’s life cycle, encompassing production, usage, and end-of-life recycling. The results of the EuCia Eco Impact Calculator and from the literature reveal that the raw materials extraction and use phases are the most energy-intensive and contribute mainly to the environmental footprint of the battery pack. For a single battery pack for EV, the CED is 13,629.9 MJ, and the CO₂ eq emissions during production are 1323.9 kg. These results highlight the need for innovations in material sourcing and design strategies to mitigate these impacts. Moreover, the variations in recycling methods were assessed using a sensitivity analysis to understand how they affect the overall environmental impact of the system. Specifically, shifting from mechanical recycling to pyrolysis results in an increase of 4% to 19% of the total CO₂ emissions (kg CO₂). Future goals include building a laboratory-scale model based on the prototype described in this paper to compare the environmental impacts considering equal mechanical properties with alternatives currently used in the automotive industry, such as aluminum and steel alloys. Full article

The effects of red mud on the microstructures and high-temperature tensile properties of the ZL109 aluminum alloy have been investigated. Red mud/ZL109-based composite materials with added red mud (a major byproduct of the aluminum industry), which has been coated with nickel by chemical deposition, have been prepared through gravity casting. The results show that the addition of red mud promotes the alloy’s microstructure and helps to uniformly distribute the eutectic silicon. It also increases the content of heat-resistant phases, such as the Q-Al₅Cu₂Mg₈Si₆ and γ-Al₇Cu₄Ni phases. These changes significantly enhance the alloy’s high-temperature tensile properties. The alloy with 1% (wt.%) red mud exhibits the best tensile strength at both room temperature and 350 °C, reaching 295.4 MPa and 143.3 MPa, respectively. The alloy with 1.5% (wt.%) red mud demonstrates excellent performance at 400 °C, achieving a tensile strength of 86.2 MPa through the cut-through method and Orowan mechanism. As a reinforcing material, red mud not only improves the high-temperature resistance of the aluminum alloy but also provides a way to recycle industrial waste. This study offers a new way to address the red mud waste problem and helps develop high-performance, heat-resistant aluminum alloys. It shows the potential of these alloys in high-temperature applications. Full article