Primary Aluminum Research Articles

Influence of Sintering Temperature on the Microstructure and Mechanical Behavior of Recycled AA2124

Aluminum and its alloys are versatile materials with inherent properties that can be enhanced through alloying. Powder metallurgy (PM) enables the production of high‐strength alloys from elemental powders, which are compacted, sintered, and calibrated to the final dimensions. In this article, recycled aluminum powder is used to produce aluminum alloy 2124 via PM. The samples are compacted at 700 MPa and sintered at 550, 575, and 600 °C. Microstructural and mechanical characterizations are performed, including Thermo‐Calc modeling, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, compression, and hardness tests. The results indicate that the optimal sintering temperature for achieving maximum relative density is 550 °C, with a peak value of 98%. However, the sintering condition that exhibited the best mechanical performance and microstructural balance is 575 °C. Compared to the primary aluminum alloy, the recycled AA2124 exhibits superior relative density and enhances compressive strength, reaching an ultimate strength of 380 MPa and 33% elongation at 575 °C. This improvement is attributed to a well‐balanced microstructure characterized by a refined distribution of precipitates, enhanced dispersion, and effective densification.

A New Approach to Evaluating Friction and Wear Behavior of α-β Phase of AA6061 and CuZn37Pb2 under Different Testing Conditions

Wear is a persistent industrial problem caused by the interaction of many interlocking and complex elements. CuZn37Pb2 and AA 6061 are particularly prone to wear due to their numerous industrial applications. To address this problem and contribute to the scientific literature, a comprehensive experimental investigation was conducted to understand and analyze the impact of these interconnected factors. This research developed a dry and lubricated horizontal lathe wear test apparatus. Various parameters, including contact temperature, wear loss, wear rate, and friction coefficient, were compared across different initial surface roughness levels, loads, sliding speeds, wear track diameters, and track widths. Experiments were performed at torques ranging from 25 to 100 N, speeds of 0.30, 0.40, and 0.50 m/s, and wear track diameters of 4, 6, 8, and 10 mm. SEM-EDS, XRD, and optical microscopes were used to examine each sample's worn surfaces and wear tracks. The morphological structure of the sample and the type of test have distinct impacts on the tribological response of the surfaces, each of which interacts uniquely, with influence varying depending on the tribological parameters. Generally, secondary phases (AA 6061) can lead to improved wear resistance due to their harder and more wear-resistant nature compared to the primary aluminum matrix. Conversely, the alpha phase of CuZn37Pb2 is harder and stronger than the beta phase and thus has better wear resistance properties. The error in wear rate calculations is 58.6% in both tests. The findings indicate that the tribological response in ideal laboratory conditions differs from that in actual field environments. This research provided significant insights into understanding and analyzing wear by addressing the largest number of characteristics previously unexplored. Additionally, the findings revealed that while completely eliminating wear is challenging, it can be significantly reduced. Laboratory wear experiments can be extrapolated to field wear tests, offering prototypes for industrial challenges and linking academic research with industry issues.

Toward Material Circularity and Manufacturing Sustainability in the Automotive Industry

ABSTRACTThis paper reviews technologies being developed toward material circularity and manufacturing sustainability in the automotive industry; aluminum sustainability is used herein as an exemplar. While aluminum is increasingly used for lightweighting applications in the transportation industries to reduce energy consumption and carbon footprint, primary production of aluminum is energy‐intensive with significant CO2 emissions. However, remelting aluminum scrap only uses ~5% of the energy, resulting in significantly reduced emissions required to produce primary aluminum from bauxite ore. The wide use of recycled aluminum for transportation applications will ensure the sustainability of the supply chain. Another example is the use of renewable wood materials such as the recently developed “super wood” which is a densified natural wood with similar mechanical properties to metallic materials. For manufacturing processes, the development and evolution of energy‐efficient large thin‐wall die casting (also called mega/giga casting) will enhance the sustainability of automotive manufacturing. Alternative energy vehicles tend to have more simplified body structures, enabling the use of large and consolidated castings which significantly reduce welding, joining, and assembly operations. Reclaiming some of the high‐value battery materials from electric vehicles is challenging. A patented “Hydro‐to‐Cathode” direct precursor synthesis process can leach out impurities, keeping the valuable metals in solution and eliminating multiple steps in the recycling flow. Additional technology advances are required to reclaim other materials. Ultimately, the combination of recycled/renewable materials and energy‐efficient manufacturing processes will drive the automotive industry toward circularity and sustainability.

Technoeconomic feasibility of integrating carbon capture technology with primary aluminum production using an advanced cogeneration waste heat recovery system

Technoeconomic feasibility of integrating carbon capture technology with primary aluminum production using an advanced cogeneration waste heat recovery system

Advancing Sustainability in Alloy Production: The Role of Recycled Materials and Barbotage in Enhancing EN AC-46000 Castings

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.

Influence of remelting on AlSi9Cu3 (Fe) alloy properties

Abstract The focus of casting production on raw materials as a starting point of all industrial value chains is more intense due to legislative and recently the difficulties faced by casting manufacturers. Critical (CRMs) and strategic raw materials (SRMs) are often indispensable inputs for a wide set of strategic sectors including renewable energy, the digital industry, the space and defence sectors and health sector which are all connected to the metal industry. Aluminium and its alloys plays an important CRMs and SRMs. Recycling has become a very important term for environmental protection as it reduces the carbon footprint of the foundry supply chain. The importance of recycling or the use of secondary or scrap raw materials is demonstrated by the fact that only 5% of greenhouse gases are released in the production process compared to the production of primary aluminium. Standard aluminium alloy AlSi9Cu3(Fe) (EN AC 46000) is widely used in the automotive and transport industry. High mechanical properties such as strength and hardness, as well as elongation and corrosion resistance are the main advantages of AlSi9Cu3(Fe) alloy. The quality of an alloy is mainly influenced by the properties of the raw material, the melting treatment and the casting technology. The significant use of secondary, i.e. recycled raw material and also of CRM, requires special attention to the chemical composition due to possible deterioration caused by repeated remelting, which can lead to a deterioration of mechanical and other performance properties. A prerequisite for good functional properties is the development of the microstructure. In this work, the influence of completely returned material (secondary raw material—scrap) as the only input charge material for the production of AlSi9Cu3(Fe) alloys by remelting on the development of the microstructure due to thermodynamic interactions of elements present was investigated. The presence of wide range of alloying elements AlSi9Cu3(Fe) alloys indicates development α-Al15Si2M4 (M = Cr, Fe and Mn), β-Al 5 FeSi, Al 2 Cu and even more complex one such as Al 3 Cu 2 Mg 9 Si 7 using theoretical modelling. Complex solidification path indicates primary aluminium αAl, eutectic phase αAl + βSi, intermetallic phase on the iron base in Al5FeSi and “Chinese script” morphology, intermetallic phase on the magnesium and copper base such as Al2Cu and complex intermetallics such as Al3Cu2Mg9Si7 phase. Thermodynamic effects of elements interaction during solidification sequence significantly influence on solidification path and manner. Although the investigated samples exhibit high tensile strength and elongation, a slight deterioration of the chemical composition, and therefore in thermodynamic effect, has a significant influence on the development of the microstructure. Despite the deterioration of chemical composition, obtained microstructure was correct and, therefore, justified achieved high mechanical properties. Based on the investigation of the thermodynamic, microstructural and mechanical properties of the secondary AlSi9Cu3(Fe) alloy, the completely return raw material was characterised as a high-quality charge material with good application and recycling potential.

Analysis of Energy Sustainability and Problems of Technological Process of Primary Aluminum Production

This paper is devoted to the problem of magnetohydrodynamic stability (MHDS) in the energy-intensive process of primary aluminum production by electrolysis. Improving MHDS control is important because of the high costs and reduced efficiency caused by the instability of magnetic and current fields. In this work, a methodological analysis of modern theoretical and numerical methods for studying MHDS was carried out, and approaches to optimizing magnetic fields and control algorithms aimed at stabilizing the process and reducing energy costs were considered. This review identified key challenges and proposed promising directions, including the application of computational methods and artificial intelligence to monitor and control electrolysis in real time. In this paper, it was revealed that wave MHD instability at the metal–electrolyte phase boundary is a key physical obstacle to further reducing specific energy costs and increasing energy stability. The novelty of this paper lies in an integrated approach that combines modeling and practical recommendations. The purpose of this study is to systematically summarize scientific data, analyze the key physical factors affecting the energy stability of electrolyzers, and determine promising directions for their solution. The results of this study can be used to improve the energy efficiency and environmental friendliness of aluminum production.

Primary Aluminium Production and Energy Intensity: Long-Run Dynamics Explored through the ARDL Approach

The escalating global demand for aluminum has highlighted various environmental challenges associated with its production, with energy consumption emerging as the predominant factor. Aluminum production is inherently energy-intensive, necessitating a thorough understanding of the relationship between energy consumption and production efficiency to enhance sustainability across both economic and environmental dimensions. It is particularly crucial as the industry faces increasing pressure to minimize its environmental impact while simultaneously meeting growing global demand. This study examines the long-term dynamics between global primary aluminum production and energy intensity from 1980 to 2023 using the Autoregressive Distributed Lag (ARDL) approach. This econometric method facilitates a detailed examination of the temporal interactions between these two pivotal variables. The analysis reveals a significant inverse relationship, where a 1-unit reduction in smelting energy intensity correlates with an approximate 10.76-unit increase in primary aluminum production. This finding underscores the critical importance of improving energy efficiency within the aluminum sector as a strategy to foster higher production while concurrently reducing energy consumption. Additionally, the study highlights the significance of technological advancements and process optimization in mitigating energy intensity, reinforcing their role in fostering sustainable production practices.

Investigation of Aluminium White Dross for Hydrogen Generation Hydrolysis in Low-Concentration Alkali

In this work, three samples of primary aluminium dross were investigated and compared to construction aluminium waste. The composition was determined, and an evaluation of hydrogen generation via hydrolysis in a low-concentration alkali solution was performed. The composition revealed low to moderate aluminium content and the presence of various crystalline phases; hydrolysis reactions showed hydrogen generation’s direct dependence on the amount of aluminium present, which translated into variation in the volume per sample mass. It was found that the composition played a substantial role in the evolution of hydrogen and its purity, simultaneously indicating a possible opportunity for dross use in hydrogen generation and power production. It was revealed that, in addition to the expected hydrogen, methane was released from some dross samples during the hydrolysis reaction. To compare the reaction kinetics, the reaction rate was obtained using the spherical solid particle shrinking core model and compared with that of construction aluminium waste. Hydrogen generation was compared to that in the known literature, and the dependence on the sample composition was determined.

Life Cycle Assessment of Primary Aluminum Production

Life cycle assessment (LCA) is used to quantitatively analyze the energy consumption and environmental impact of primary aluminum production in China, the United States, and Europe, as well as global average. The results indicate that electricity and fuel contribute more than 60% of the environmental impact of bauxite mining; steam is the greatest contributor to the environmental impact of alumina production by the Bayer process, with a result exceeding 35%; and electricity contributes >50% of the environmental impact of aluminum electrolysis. The environmental impact of primary aluminum production in China is 1.2 times the global average. The contributions of the three stages of primary aluminum production to the total environmental impact of the process in China are, in descending order, aluminum electrolysis (64.33%), alumina production (33.09%), and bauxite mining (2.58%). If the proportion of thermal power in the electricity source structure is reduced from 60% to 0%, the contribution of electricity to the environmental impact of primary aluminum production will decrease from 38% to 2%, and the total environmental impact will decrease by 73%. Therefore, energy conservation and emissions reduction can be realized through the optimization of the power generation structure, adoption of clean energy production, and improvement of the heat utilization rate in production processes.

Processing used Aluminium Production Granular Filters to Produce Concrete

This article presents the findings of experimental studies on the involvement in the processing of spent filters from ash and slag waste used in the refining of primary aluminum as a filler for concrete production. The processing of spent granular filters was conducted in three stages. The first stage involved the preliminary processing of filter grains to remove aluminum scrap. The second stage entailed the metallurgical processing of separated aluminum scrap through remelting in an induction crucible furnace and subsequent refining. The third stage focused on the production of a concrete mixture comprising crushed spent filter grains, quartz sand, bauxite sludge, screenings of crushed rocks with a fraction of 20 mm–30 mm, and Portland cement. This mixture was used to create samples of building products. The test results indicate that the tensile strength of the concrete samples for building products ranges from 20.89 MPa to 37.75 MPa, depending on the Portland cement content. This strength corresponds to that of heavy concrete.

Microstructural characterization of primary and recycled aluminum AlSi7Mg alloy processed by the semi-solid thixocasting method

Microstructural characterization of primary and recycled aluminum AlSi7Mg alloy processed by the semi-solid thixocasting method

Numerical Prediction of Fracture and Perforation Behaviours of Recycled Aluminium Alloy AA6061 Using Taylor Cylinder Impact and Perforation Tests

Directly recycled AA6061, valued for its energy-efficient production and reduced environmental impact compared to primary aluminium, exhibits unique mechanical properties due to microstructural changes during recycling. Behavioural analysis under various loading conditions, including tensile and impact tests, reveals mild ductility and anisotropic deformation patterns such as petal formation, plugging, and fragmentation. This study investigates the fracture and perforation behaviour of AA6061 plates under high-velocity impacts using a numerical model based on the Johnson-Cook material and failure models. Simulations of Taylor cylinder impact tests, conducted at velocities ranging from 280 m/s to 370 m/s, show strong agreement with experimental data, validating the Simplified Johnson-Cook model’s effectiveness in predicting fracture behaviour under impact loading. Building on these results, the study explores the Johnson-Cook Failure Model in perforation tests with severely fractured specimens. Simulations accurately predict perforation behaviour at lower impact velocities and smaller bullet diameters, particularly in cases of limited deformation. However, at higher velocities and larger bullet diameters, prediction accuracy decreases due to complex fracture patterns and asymmetric deformations. The study concludes that while the current failure model provides a foundational understanding of fracture and perforation behaviour in recycled AA6061, further refinements are necessary. Enhancing the failure model, specifically for recycled aluminium, could improve its predictive accuracy across a broader range of impact scenarios, addressing the limitations observed in cases of severe deformation and complex fracture mechanisms.

Different technology packages for aluminium smelters worldwide to deliver the 1.5 °C target

Production of aluminium, one of the most energy-intensive metals, is challenging for mitigation efforts. Regional mitigation strategies often neglect the emissions patterns of individual smelters and fail to guide aluminium producers’ efforts to reduce GHG emissions. Here we build a global aluminium GHG emissions inventory (CEADs-AGE), which includes 249 aluminium smelters, representing 98% of global primary aluminium production and 280 associated fossil fuel-based captive power units. We find, despite the installation of more efficient and higher amperage cells, that the share of aluminium production powered by fossil fuel-based captive power units increased from 37% to 49% between 2012 and 2021. Retiring fossil fuel-based captive power plants 10 years ahead of schedule could reduce emissions intensity by 5.0–10.5 tCO2e per tonne of aluminium for dependent smelters. At least 18% of smelting capacity by 2040 and 67% by 2050 must be retrofitted with inert anode technology to achieve net-zero targets.

Upcycled high-strength aluminum alloys from scrap through solid-phase alloying

Although recycling secondary aluminum can lead to energy consumption reduction compared to primary aluminum manufacturing, products produced by traditional melt-based recycling processes are inherently limited in terms of alloy composition and microstructure, and thus final properties. To overcome the constraints associated with melting, we have developed a solid-phase recycling and simultaneous alloying method. This innovative process enables the alloying of 6063 aluminum scrap with copper, zinc, and magnesium to form a nanocluster-strengthened high-performance aluminum alloy with a composition and properties akin to 7075 aluminum alloy. The unique nanostructure with a high density of Guinier-Preston zones and uniformly precipitated nanoscale η‘/Mg(CuZn)2 strengthening phases enhances both yield and ultimate tensile strength by >200%. By delivering high-performance products from scrap that are not just recycled but upcycled, this scalable manufacturing approach provides a model for metal reuse, with the option for on-demand upcycling of a variety of metallic materials from scrap sources.

Impact of Scrap Impurities on AlSi7Cu0.5Mg Alloy Flowability Using Established Testing Methods

In view of the increasing demand for secondary aluminum, which is intended to partially replace the very energy- and resource-intensive primary aluminum production, effective treatment methods can maintain the high quality level of light metal castings. The transition from a linear to a circular economy can result in an accumulation of oxides or carbides in aluminum. Therefore, melt purification is crucial, especially as foundries aim to increase the use of often dirty end-of-life scrap. Nonmetallic inclusions in the melt can impact its flowability and mechanical properties. As the purity of the melt increases, its flow length also tends to increase. Available assessment methods like reduced pressure test or K-mold are capable of ensuring high levels of purity. This study demonstrates the implication of inclusions originating from dirty scrap. An experimental test run deals with various scrap contents in an AlSi7Cu0.5Mg alloy and shows correlations between impurity and performance, expressed by flowability and mechanical properties. These performance indicators have been connected to inclusion and porosity rates. In conclusion, these findings emphasize the need for further extensive research on contaminants in the field of scrap melting and the development of methods for easy-to-handle assessment methods.

The effect of vanadium on the performance properties of Al–2.3%V alloy manufactured by 3D printing

X-ray diffraction analysis, ellipsometry and optical microscopy have been used to study aluminum alloys samples (Al and Al–2.3% V) fabricated by 3D printing using selective laser melting. The mechanical properties of the resulting products have been compared. The strength and plastic properties of parts made from pure Al and Al–2.3% V alloys have been found to be insensitive to heat treatment. The addition of vanadium to pure Al showed that the Al–2.3% V alloy has significantly improved performance properties compared to those of primary aluminum, without affecting its initial plasticity.

Analysis of the load structure in the processing of aluminum alloys for automotive rims

Abstract The most commonly used aluminum alloys for manufacturing rims are the deformable alloys 6082 and 6061, as well as the casting alloy AlSi11. The increasing demand for such materials has led to intensified research and development activities in the field of high-strength and high-ductility aluminum alloys. Aluminum alloy rims must meet certain critical safety requirements and adhere to high standards of design, technical conditions, and processing. This paper presents the research conducted and the results obtained regarding the load structure in the processing of 6082 aluminum alloys intended for rim manufacturing. The load consists of aluminum waste and primary aluminum in various proportions depending on the alloying elements added to the metal bath of the waste used in the recipes.

The Study of Porosity in A356 Secondary Aluminium Alloys with Higher Iron Content

Abstract The production of secondary (recycled) aluminium has gained significant importance in recent years, driven by the need to reduce electricity consumption and waste associated with primary aluminium production. Secondary aluminium alloys thus play a vital role in sustainable industrial practices, particularly within sectors such as automotive, aerospace and marine. Recently, these alloys have gained traction in electric vehicle components manufacturing, where lightweight and sustainable materials are critical to enhancing energy efficiency and extending vehicle range. However, secondary aluminium alloys are prone to impurities and casting defects, notably porosity, which presents challenges in achieving optimal mechanical properties and surface quality. Porosity reduces corrosion resistance, fatigue, and tensile strength, thus impacting overall material performance. This porosity can be categorised by size (microporosity and macroporosity) and origin, with gas and shrinkage porosity being the primary types. This study examined experimental A356 secondary aluminium alloys with varying iron contents in as-cast and T6 heat-treated conditions. The analysis focused on the quantitative assessment of casting defects within the microstructure, specifically, the types of pores present, the area percentage of pores, and average pore size. These insights contribute to a deeper understanding of how casting defects impact the performance of recycled aluminium alloys in sustainable applications, particularly in the context of next-generation electric vehicles.

Thermodynamic modeling of the processes of purification of primary aluminum from vanadium impurities

This article discusses the interaction of chemical elements in the three-component Al-V-B system. Vanadium reduces electrical conductivity in primary aluminum, which requires its reduction during aluminum electrolysis to values less than 0.02%. In order to reduce the concentration of vanadium impurities, thermodynamic calculations were carried out for the reactions of separation of the metallic phase of aluminum and impurities of vanadium intermetallic compounds through the use of a boron-containing flux. The calculation of thermodynamic parameters was carried out in HSC Chemistry 9.0. for AlB2 and VB2 compounds, the chemical reaction AlB2 + V = VB2 + Al within the operating temperatures of electrolysis and casting of primary aluminum of 650–950°С and the conditions of immersion of boron-containing flux into the melt to a ladle depth of 0.5, 1.0, 1.5 and 2 m, i.e. within the pressure range of 102.39–148.99 kPa. Thermodynamic analysis showed that the Gibbs energy (ΔGT) values in the entire range of operating temperatures of the electrolysis and casting of primary aluminum for VB2 are significantly lower than AlB2, therefore, they will be formed predominantly in this temperature range. The order of stability also suggests that vanadium can be easily removed from aluminum melts by adding boron. The results obtained allow us to conclude that chemical reactions of primary aluminum purification from vanadium impurities can occur due to boron additives.