Aluminum Melt Research Articles

Effects of Multiple Factors on the Compressive Strength of Porous Ceramsite Prepared from Secondary Aluminum Dross

Aluminum is one of the most in-demand nonferrous metals in the world. The secondary aluminum dross (SAD) produced during aluminum smelting is a type of solid waste that urgently requires disposal. SAD, municipal solid waste incineration fly ash, and bottom slag were used as raw materials to prepare porous ceramsite in a laboratory in this study. Multi-factor design experiments were then used to explore the influence of the sintering condition on the compressive strength to provide a basis for ceramsite preparation using SAD. The results showed that, within a certain variation range, the levels of each factor showed overall positive correlations with the ceramsite compressive strength. The contributions of the ceramsite particle size, the silicon–aluminum ratio (Si/Al), the sintering temperature, and the sintering time to the compressive strength of the porous ceramsite then decreased. The factors had a synergistic effect. The interactive effect of multiple factors on the porous ceramsite compressive strength rose with an increase in the particle size and Si/Al ratio. The average compressive strength of the porous ceramsite prepared in this study was 4.06 ± 3.71 MPa, and the maximum compressive strength was 14.13 MPa. The highest ceramsite compressive strength was achieved under a sintering temperature of 1270 °C, a particle size of 2 cm, a sintering time of 30 min, and a silicon–aluminum ratio of 1.5. In addition, there was a reaction relationship between the multiple factors involved in the sintering of the SAD-based porous ceramsite. Pilot or industrial tests should be conducted in the future based on these experiments and the intended ceramsite use.

Viability of Flax Fiber-Reinforced Salt Cores for Aluminum High-Pressure Die Casting in Experiment and Simulation

AbstractParts with undercuts or hollow sections exploit the maximum lightweight potential due to efficient material usage. However, such geometries are often challenging to produce with ordinary tooling technology, especially in aluminum high-pressure die casting (HPDC). In order to close this gap, this paper investigates flax fiber-reinforced salt made by wet compression molding as a new lost core material that can be removed with water. Three-point bending tests and HPDC experiments characterized the material. The 2D and 3D simulations with aluminum melt and compressible air were carried out in ANSYS Fluent 2023R1. The outlet vent boundary condition is characterized separately to address the geometric features of the outlet vent. Combined with a two-phase flow filling simulation, it allows assessing the actual loads on the lost core material. The simulations show an excellent agreement between the proposed one-dimensional, analytical outlet model and the computational fluid dynamics (CFD) results. The 2D filling simulations are helpful to prove mesh convergence and model simplifications but overestimate the loads. A 3D simulation predicts stress peaks up to 33 MPa for an ingate speed of 64 m/s. Conventional, brittle salt cores with a bending strength of 15 MPa fail under these conditions in the HPDC experiment. In contrast, fiber-reinforced salt cores with bending strengths between 11 and 37 MPa are viable thanks to their toughness, which was demonstrated by a eight to 31 times higher energy absorption than the unreinforced benchmark in the three-point bending tests. With the new robust lost core material, a foundry gains a technology advantage that opens up new markets, e.g., in the mobility sector.

Formation of aluminum nitride in dross by contact-diffusion reaction during aluminum recycling

Secondary aluminum dross is a solid waste after aluminum extraction from the slag produced during aluminum recycling. It is classified as a hazardous waste due to the high content of active aluminum nitride (AlN). This work studied the thermodynamics and kinetics of AlN formation in aluminum dross. Aluminum tends to react with N2 to form AlN, when the partial pressure of nitrogen (N2) is much greater than that of oxygen (O2) (PN2≫PO2) in thermodynamics. Additionally, the reaction between aluminum and N2 is accelerated with the increasing temperature. Approximately 36.37 wt% of aluminum was transformed into AlN at 700°C according to kinetic analysis. Aluminum recycling involves smelting, refining, and dross processing. The dross produced from these different processes has various compositions and hazardous properties. The formation mechanism of AlN from the three processes was revealed based on the thermodynamic and kinetic analyses. The reaction mechanisms in these processes were identified as surface contact reaction, internal and surface contact reaction, and rotational surface contact reaction between the aluminum melt and N2, respectively. X-ray diffraction (XRD) and electron probe microanalysis (EPMA) analyses were used to determine the phase and composition of the aluminum dross. The nitrogen content in the aluminum dross from smelting, refining, and dross processing was found to be 3.3 wt%, 5.2 wt%, and 9.6 wt%, respectively. The monthly dross production were 276.3 tons, 22.7 tons, and 318.2 tons, respectively, according to statistics. It was calculated that the nitrogen generated in the three process was 9.12 tons, 1.18 tons, and 20.25 tons, respectively. Therefore, dross processing is the primary source of AlN. A rapid dross processing method with small-scale vertical stirring was proposed to shorten the reaction between the aluminum melt and N2, thereby reducing AlN formation. This work could provide guidance for reducing hazardous AlN in aluminum dross and optimizing the aluminum recycling process.

Microbial communities of urban and industrial polluted soils in the Russian Arctic

The Russian Arctic presents a unique environment for studying the effects of anthropogenic pressure on soil microbial communities under severe climatic conditions. This study investigated the impact of chemical pollution on soil microbial properties by comparing urban and industrially polluted soils in Murmansk region with natural Podzols. Urban soils exhibited significant alterations, including shifts in pH and increased carbon and nutrient contents compared to natural soils. Industrially polluted soils near the copper‑nickel smelter were characterized by elevated heavy metal concentration, while those near the aluminum smelter showed high fluorine and aluminum content. In both cases, carbon content and pH remained similar to natural soils. Industrial emissions significantly changed the soil microbiome, with effects varying depending on the pollution source and chemical composition of the emissions. Soils near the copper‑nickel smelter showed a decline in bacterial gene copies and actinomycete mycelium length, with a predominance of Chloroflexii and Ascomycota. Conversely, soils near the aluminum smelter exhibited less pronounced changes, with Proteobacteria and Basidiomycota being prevalent. Despite these differences, both industrially impacted sites displayed reduced microbial diversity, regardless of the composition of the emissions. In contrast, urban soils demonstrated increased microbial diversity, likely attributed to the emergence of new, favorable ecological niches. Microbial communities in both cities were similar, dominated by Proteobacteria and Ascomycota, and displayed an increase in bacterial gene copies compared to natural soils. These findings highlight the contrasting influences of urban and industrial development on soil microbial communities. While industrial activities suppress microbial life, urbanization fosters the creation of new niches, promoting microbial diversity. This underscores the potential of urban soils to support diverse microbial communities, which is crucial for sustainable development and ecological strategies in Arctic cities.

Energy Flexibility in Aluminium Smelting: A Long-Term Feasibility Study Based on the Prospects of Electricity Load and Photovoltaic Production

This paper investigates the economic feasibility of utilising energy flexibility in aluminium production as a viable solution to leverage electricity surpluses arising from the increasing number of photovoltaic (PV) system installations. Future trends suggest that the generation capacity of PV systems will soon surpass consumption, leading to significant electricity surpluses, particularly during the summer. This surplus electricity, which is anticipated to be available at low prices, offers a unique opportunity to evaluate different investment and utilisation scenarios for aluminium production while simultaneously decreasing its environmental impact. The results demonstrate that, despite their high initial investment cost, large-scale PV power plants can potentially deliver maximum economic gains over a ten-year period. Conversely, the direct utilisation of surpluses without substantial investment can yield savings of up to EUR 17 million within the same time frame for Slovenia’s case with an aluminium smelter, which has a maximum power usage of 60 MW. The findings of this study have significant implications in terms of shaping future energy strategies and policies, emphasizing the value of integrating renewable energy sources and industrial processes for enhanced economic and environmental outcomes.

Study on the mechanism of aluminum melt corrosion of Fe-SG series metals

This paper investigates the corrosion behavior of Fe-SG series metals with different graphite nodule counts to molten Al by using the ultrasonic vibration hot-dip aluminum experimental method. Fe-SG series metals to aluminum melt exhibited a much better corrosion resistance compared to H13 tool steel. As the graphite nodule count increases, the hot melting loss rate of Fe-SG series metals gradually decreases, indicating an improvement in corrosion resistance to aluminum melt. Scanning and EDS analysis of the samples after hot-dip aluminum testing revealed that the thickness of the product layer increased progressively with the extension of hot-dip aluminum time. Through the analysis of the structure and composition of the product layer, it was found that the corrosion products in H13 steel were composed of Fe2Al5 and FeAl3. In addition to the two phases, the product layer of the Fe-SG series metals also contained granularly distributed Fe–Al–Si intermetallic compounds within the Fe2Al5 phase. This resulted in a better corrosion resistance to aluminum melt.

Hybrid numerical 3D model of electromagnetic levitation of molten metal

This paper introduces a new and efficient methodology for the numerical modeling of electromagnetic levitation. The model requires transferring the time-varying geometry of the molten metal from the hydrodynamic submodel to the electromagnetic submodel. The developed methodology combines a geometry transfer of the conductivity distribution of the metal/air system, and the accompanying conditional reconstruction of the electromagnetic submodel. The proposed solution strategy enables a computationally efficient simulation of the coupled process accounting for any evolution of the molten metal geometry. The developed methodology can be generalized to any magnetohydrodynamic process with the presence of a free surface of liquid metal. The method was applied to the 3D modeling of a classic example of low-scale levitation melting of aluminum.

Selective Processing of the Kaolinite Fraction of High-Silicon Bauxite

When processing low-quality gibbsite–kaolinite bauxites, technologies that involve different methods of mechanical and chemical enrichment with the separation of a difficult-to-utilize fine kaolinite fraction for disposal are used. Before production, problems related to waste storage and disposal arise. To solve the problem of utilization, it is necessary to develop an effective technology for the selective processing of the kaolinite fraction. The efficiency of the technology will depend on the quality of pretreatment of raw materials prior to processing for Al2O3 extraction. Preliminary preparation of kaolinite fraction is associated with the maximum removal of excess silica during chemical enrichment by treatment with an alkaline solution. The presence of silica reduces the quality of final alumina products and requires a large consumption of reagents during the desiliconization of aluminate solutions. During the chemical enrichment of kaolinite fraction in alkaline solution, a serious problem of the co-dissolution of Al2O3 with silica arises. The solution to this problem can be the transformation of phase composition with the transformation of kaolin into a chemically resistant compound corundum, which will create conditions for the selective removal of silica. Kazakhstan’s alumina refinery, Pavlodar Aluminum Smelter, processes low-quality gibbsite–kaolinite bauxite from the Krasnogorsk deposit. To improve the quality of bauxite, preliminary gravity enrichment is carried out to separate the kaolinite fraction to a quantity greater than 50%. The purpose of this work was to study the possibility of the selective processing of the kaolinite fraction via various techniques, including preliminary thermal transformation, through sintering, chemical enrichment, autoclave leaching in a circulating aluminate solution, and low-temperature desiliconization, to obtain a solution for decomposition. As a result of this study, the possibility of obtaining a corundum phase after sintering at a temperature of 900–1000 °C was established, which made it possible to obtain 58.8% chemical enrichment through the extraction of SiO2 into solution. Further use of the enriched kaolinite fraction in autoclave leaching in a circulating aluminate solution with low-temperature desiliconization made it possible to obtain an aluminate solution with a caustic modulus of 1.65–1.7, which is suitable for decomposition.

Comparison of urinary 3-hydroxybenzo(a)Pyrene (3-OHBaP) and trans-anti-7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydrobenzo(a)Pyrene (TetraolBaP) as biomarkers of exposure to carcinogenic BaP

IntroductionBiomonitoring of exposure to carcinogenic Benzo(a)Pyrene is generally based on measurement of urinary 3-hydroxybenzo(a)pyrene (3-OHBaP), but its analysis is complex and only reflects the BaP detoxification pathway. TetraolBaP, another BaP metabolite resulting from the metabolic activation pathway, is now available but has not yet been studied in occupational settings or compared with 3-OHBaP. MethodsBiomonitoring was carried out on 118 subjects working in the aluminium smelting industry. 3 urine samples were collected from each subject at the beginning and end of the working week. Pyrene metabolite (1-hydroxypyrene) and the two BaP biomarkers (3-OHBaP and TetraolBaP) were analysed using LC-Fluorescence and GC-NCI-MS-MS. ResultsThe workers studied were found to be highly exposed, with 1-OHP and 3-OHBaP frequently exceeding maximum recommended values in occupational settings. Maximum concentrations were measured at end of shift+16h for all biomarkers, highlighting dermal exposure and/or temporary storage. Correlations were strong between 1-OHP and 3-OHBaP (r = 0.68–0.75) as well as between 3-OHBaP and TetraolBaP (r = 0.67–0.78), and moderate between 1-OHP and TetraolBaP (r = 0.59–0.76). While TetraolBaP levels were higher at low PAH exposures, TetraolBaP increased much more slowly at high exposures, indicating progressive saturation of the bioactivation pathway. The [3-OHBaP]/[TetraolBaP] ratio was found to be significantly lower in chronically exposed workers. Urinary TetraolBaP levels corresponding to 1-OHP (2.5 μg/L or 1 μmol/mol creatinine) or 3-OHBaP (0.4 nmol/mol creatinine) guidance values were found to range between 0.84 and 0.95 nmol/mol creatinine. ConclusionsTetraolBaP, resulting from carcinogenic BaP's metabolic activation pathway, was shown to be a diagnostically specific and sensitive biomarker for determining subjects' toxic internal exposure to PAHs in different contexts (occupational settings, environment) and assessing health risks.

Al-Ti-C (CNTs) master alloys improve room temperature and high-temperature mechanical properties of ZL205A alloy

The insufficient high-temperature properties of Al-Cu alloys represent a significant obstacle to their further development. The use of master alloy refiners can enhance the mechanical properties while refining the grains. This paper describes the preparation and characterization of Al-Ti-C (CNTs) master alloys containing submicron TiC particles through the aluminum melt reaction method, utilizing graphite powders (GPs) and (CNTs) as carbon sources,respectively.The effects of these two types of intermediate alloys on the microstructures and high-temperature mechanical properties of the ZL205A alloy were investigated at varying additive amounts. The results indicate that the Al-Ti-C (CNTs) master alloys contain TiC particles measuring up to 183 nm and 480 nm, respectively, with the Al-Ti-CNTs demonstrating a superior effect on the refinement of the ZL205A alloy. The optimal mechanical properties were achieved upon the addition of 0.3 wt% of the master alloy to the ZL205A alloy. The mechanical properties improved from 341.53 MPa (yield strength), 371.68 MPa (tensile strength), and 3.3 % elongation without the addition of master alloys to 413.20 MPa, 471.82 MPa, and 11.2 % with the addition of Al-Ti-CNTs and to 440.85 MPa, 492.61 MPa, and 10.8 % with the addition of Al-Ti-C, respectively.At a high temperature of 300°C, the mechanical properties of the ZL205A alloy improved from 144.0 MPa and 10.8 % (Al-Ti-C) to 174.87 MPa and 11.2 %, and 195.1 MPa and 13.8 % (Al-Ti-CNTs). The TiC particles generated in situ under a different carbon sources demonstrated distinct mechanisms in the grain refinement of the ZL205A alloy. TiC (GPa) with a larger size primarily impeded the further growth of grains, while TiC (CNTs) promoted the formation of crystalline nuclei and heterogeneous nucleation sites, thereby achieving grain refinement. Large-sized TiC particles prepared using graphite as the carbon source hindered further grain growth, whereas TiC produced using carbon nanotubes promoted the formation of nuclei and heterogeneous nucleation sites, resulting in grain refinement. In addition, both types of TiC particles contribute to the densification and strengthening of the ZL205A alloy through fine grain strengthening, precipitation strengthening, Orowan strengthening, load transfer strengthening, the pinning effect, and thermal mismatch strengthening. However,TiC(CNTs) exhibits a greater contribution to strength due to its high quantity and small size.

Effect of SF6 circuit breaker parameters on switching overvoltages evaluated based on nominal modes of converter transformers

In this work, we set out to investigate the influence of operating currents of SF6 circuit breakers on the magnitude of overvoltages during switching of converter transformers. The experience of electrical equipment operation is analyzed with a focus on the problems associated with the natural aging of insulation, overloads, and switching overvoltages. The methods of equipment diagnostics were used. According to statistical data, at present, about 37% of short circuits between phases and 42% of single-phase earth faults in electrical networks of industrial enterprises occur due to switching overvoltages. The conducted tests showed that the overvoltages emerging during switching by SF6 circuit breakers of converter transformers, which are used in aluminum smelters, may reach a three-fold rated voltage of the network. This threatens the insulation of transformer windings, cable line, and the switch itself. It was established that an increase in operating currents of an LF2 circuit breaker, not exceeding 27.8% of the rated current of the switch, leads to an increase in overvoltages during switching of converter transformers. At a further increase in the operating currents of the circuit breaker by more than 27.8% of the rated current of the circuit breaker, a sharp decrease in the value of switching overvoltages is observed. Therefore, the operating currents of SF6 circuit breakers were established to affect the level of switching overvoltages of converter transformers. The underlying mechanism of this phenomenon was determined, which should be taken into account when improving the reliability of power supply of converter transformers and, consequently, the reliability of aluminum production. The feasibly of resistive-capacitive dampers as the most effective means for limiting overvoltages during switching of converter transformers was confirmed.

FROM ENERGY INTENSITY TO SUSTAINABILITY: AN ANALYSIS OF TRENDS IN THE ALUMINIUM INDUSTRY

The article analyses trends in the aluminium industry from the point of view of sustainable development and energy efficiency. The significant impact of industrial enterprises on the environment is discussed, particularly, the high level of greenhouse gas emissions caused by energy consumption in aluminium smelting. Possibilities of reducing the negative impact due to the use of renewable energy sources, such as hydropower, as well as the implementation of energy-efficient practices, have been identified. A taxonomic analysis was used to assess the sustainable development of aluminium enterprises due to its advantage in identifying problems and directions for production improvement. The proposed method of analysis is based on the system of factors that influence the development of the industry and correspond to the concept of sustainable development. Based on the available data of the International Aluminium Institute (IAI), the analysis was carried out using the following factors: economic (volume of production, energy intensity of primary aluminium smelting, total energy consumption of production, labour productivity, impact of energy intensity on emissions), environmental (emissions of greenhouse gases and energy consumption of aluminium smelting using different energy sources), social (million hours reported worked, lost time accident rate, restricted work/medical treatment accident rate). Approbation of the proposed methodology on the example of international statistical data makes it possible to determine the biggest gaps in ensuring the sustainable development of aluminium industry production, including the use of various energy sources. Based on the results of the analysis, it was found that none of the factors used in monitoring the activities of aluminium producers reach the reference values. In the block of economic factors, the taxonomic indicator varies between 0.18 and 0.38 (the worst efficiency is observed in terms of total production volumes). Environmental factors have taxonomic values in the range of 0.07–0.36 (the largest reserves exist in ensuring the efficiency of energy consumption using hydropower, as well as reducing greenhouse gas emissions in the process of primary aluminium production). Among the social factors, the biggest problems are labour safety and lost working hours; as a result, the taxonomic indicator for this block is in the range of 0.04 - 0.33. The obtained results indicate the need for constant improvements in the production of aluminium, which is one of the main producers of greenhouse gases due to the high energy intensity of production. The proposed approach for conducting an analysis can be improved depending on the available statistical data and the goals of the analysis. In any case, it is valuable for obtaining information on the most critical areas in supporting the sustainable development of the industry.

Effective reduction of iron impurities in recycled aluminium-silicon alloy type LM-6 through sedimentation and filtration with synthesized Mn, Cr and Zr transition metal powders

Abstract In secondary aluminium recycling, impurity reduction, especially of iron, is a significant challenge as it deteriorates the material quality in the aluminium melt. Recycled aluminium alloys are widely used in various industries, including automotive, marine, and structural engineering. Specifically, LM-6 aluminium alloy is commonly used in automotive engine parts and transmission cases. This research focused on reducing the excessive iron content in LM-6 alloy scrap. Elements like manganese (Mn), chromium (Cr) and zirconium (Zr) were added to the melt in form of synthesized powders to form intermetallic compounds. These powders will also act as grain refiners, neutralizers and reducing the detrimental effects on the alloys. The powders were synthesized using the ball milling method with a ball to powder ratio of (5:1) to enhance mixing and amalgamation with the melt. The melt was held at an optimized temperature of 640 ± 10 °C to promote the formation of intermetallic sludge, encouraging the sedimentation of aluminium-iron (Al-Fe) intermetallic phases. XRD confirmed the formation of AlMn, AlCr, AlZr with other phases. After sedimentation, a glass fabric mesh with a pore size of 200 μm was used to effectively filter out β-iron during the filtration process. This technique reduced iron impurity in the melt by 50%–60%. As a result, the mechanical properties of the recycled aluminium improved significantly: hardness increased by 14%, and tensile strength increased by 36%. The wear and corrosion resistance of the material also improved due to the incorporation of the synthesized powders. SEM analysis revealed the plate-like formation of iron structures and confirmed the presence of the manganese, chromium, and zirconium powders in the metallographic analysis.

Electrochemical performance of graphene oxide synthesized from graphitic spent potlining for energy storage application

The hazardous nature of spent pot lining (SPL) generated from aluminum smelters poses environmental challenges due to its high fluoride and cyanide content. However, techniques and recent studies have shown that SPL can be converted into valuable carbon-based materials through innovative recycling with potential applications in energy storage devices. This work presents an electrochemical performance evaluation of graphene oxide (GO) electrodes derived from acid-treated SPL for supercapacitor applications. The SPL-derived graphene oxide (SPL-GO) was synthesized via a facile and scalable improved Tour method. SPL-GO electrodes were fabricated by drip-coating SPL-GO/PVDF/DMF suspension on nickel foams. The morphology, structure, and chemical composition of the SPL-GO were characterized using advanced techniques such as energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). The electrochemical properties of the SPL-GO in 3 M KOH were characterized with a three-electrode system using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The results demonstrate that SPL-GO exhibits a relatively high specific capacitance of 762.90 F/g at 1 A/g with corresponding power and energy densities of 502 W/kg and 106.60 Wh/kg, respectively. Additionally, excellent cycling stability of 85.4 % was achieved after 10,000 cycles with a coulombic efficiency of 95.23 %. These results suggest a superior rate capability of SPL-GO, rendering it a viable candidate for supercapacitor applications. Furthermore, this work sets the foundation for the sustainable use of industrial waste in energy storage devices, suggesting a novel, eco-friendly material for practical supercapacitor applications.

Ab initio molecular dynamics investigation on hydrogen diffusion behavior in liquid aluminum alloy melts

In this work, ab initio molecular dynamics (AIMD) simulations under both NVT and NPT ensembles were performed to study the influence of alloying elements of Mg, Fe, Si, Ti, Cu, Zn, F, and Cl on the H diffusion behavior in liquid aluminum melt. It is found that the diffusion coefficient of H simulated by AIMD under the NVT model is highly consistent with the reported experimental results. Specifically, the addition of Cu, Cl, Si, and Zn is inclined to increase the diffusion coefficient of H in the melt, whereas the opposite result is observed with the addition of F, Fe, and Ti. Moreover, it is proved that the H diffusion coefficients are positively correlated with the H-Al bond lengths and the coordination number of H in a constant volume system. The obtained results deepen the understanding of the diffusion of H atoms in Al melts and contribute to the optimization of existing melt purification technologies.

Silicon Refining by Growing Crystallites in a Hypereutectic Melt of Aluminum with Silicon

Silicon Refining by Growing Crystallites in a Hypereutectic Melt of Aluminum with Silicon

Anisotropic corrosion behavior of laser-based direct energy deposited H13 steel in molten ADC12 aluminum alloy

The immersion corrosion experiment of laser-based direct energy deposited H13 steel in ADC12 aluminum alloy melt was conducted to evaluate the demands for corrosion resistance after mold repair. The effect of the anisotropic microstructure of the deposited H13 steel on corrosion behavior was elucidated by characterizing the microstructure before and after corrosion. The results show that the microstructural heterogeneity affects the initiation, development and stabilization process of corrosion. Corrosion tends to initiate near the heat-affected zone due to the heterogeneous distribution of grain size, carbides, and dislocation density. Planes with weak microstructural heterogeneity are less likely to develop cracks in the intermetallic compounds (IMCs) layer during the corrosion development stage, thus exhibiting a slower corrosion rate. The IMCs layer of plane with weak microstructural heterogeneity stabilizes more quickly during the corrosion stabilization stage. The plane perpendicular to the build direction exhibits the highest corrosion resistance due to fewer corrosion initiation locations and the weakest microstructural heterogeneity. Furthermore, the composite structure of carbide core + Si phase shell, generated during corrosion, contributes to improving localized corrosion resistance. This study provides insights into understanding the influence of the heterogeneous microstructure from additive manufacturing on the reaction-diffusion process and offers guidance on direction selection when preparing components for applications in contact with aluminum melts using additive manufacturing techniques.

Global primary aluminum smelters' CO2 mitigation potential and targeted carbon-neutral pathways

The expansion of aluminum smelter capacity generates high CO2 emissions, exhibiting spatiotemporal diversity due to diverse processing routes and technologies. Despite extensive discussions on macro abatement options, facility-specific mitigation potentials and decarbonization strategies remain unclear, which cumulatively affects the progress towards global 1.5 °C and 2 °C warming control targets. This study develops a carbon footprint inventory of 163 primary aluminum smelters in 2022 and analyzes current emission structures concerning location, age, production, and input-output. Then adjust available technologies and efficiencies to match global plant-level decarbonization routes. The potential contributions of each strategy are finally quantified, accounting for significant geographic variations in emissions, thereby supplementing tailored technology transformation pathways for smelters across nine focus regions. The results show that: (1) Young smelters, predominantly in developing regions, are crucial for abatement. Rapid retrofits ahead could save CO2 budgets by 0.6–28.56 Gt, potentially delaying excess emissions under climate targets, particularly with comprehensive retrofits. (2) The paramount technical retrofitting for carbon neutrality differs regionally and evolves. Smelters in developing countries should prioritize renewable energy investment in the immediate future, succeeded by the optimization of power generation infrastructures. To liberate more emission allowances, developed countries ought to contemplate the decommissioning of aged smelters or upgrading through emerging supply-side technologies. (3) Available retrofits can facilitate the aluminum industry's contribution to the 2 °C climate target, whereas addressing the 1.5 °C target will necessitate the adoption of more innovative technologies and materials. This paper endeavors to assist global and regional smelters in developing more targeted decarbonization pathways.

Study on the Effect of Al-10Sr Intermediate Alloy on the Modification of A356 Aluminum Alloy after Different Purification Treatments

Abstract For three different purification treatment methods of aluminum melt: untreated (UT), conventional purification treatment (CPT), impurity removal flux purification treatment (IRF), and Al-10Sr intermediate alloy was applied for modification treatment. The results showed that due to the highest purity of aluminum liquid treated with IRF, the secondary dendrite spacing decreased by 31.32% after modification, and the eutectic silicon phase was in a granular and dispersed distribution. The tensile fracture exhibited ductile fracture characteristics, effectively improving the mechanical properties of the alloy. At the same time, it was found that reducing the Sr content did not decrease the modifying effect, indicating good purity of aluminum liquid can provide superior melt conditions for subsequent modification treatment.

Investigation into the effects of Na2B4O7 on the removal of titanium and vanadium from aluminium matrix

ABSTRACT This study proposes a method of adding Na₂B₄O₇ to remove titanium and vanadium impurities from primary aluminium. The effect of Na₂B₄O₇ to the aluminium melt on the removal of titanium and vanadium impurities was investigated, with a focus on the influence of varying addition amounts and holding times. According to the results, the chemical reaction occurring within the melt was postulated and a thermodynamic calculation was conducted. At 750°C and holding times of 30 min, the impurity contents of titanium and vanadium gradually decrease with an increase the amount of Na₂B₄O₇. At an addition of 0.8 wt.%, the removal rates were observed to be 53.3% and 76.3%, respectively. The impurity removal effect exhibited a positive correlation with the holding times. Holding for 90 min, the content of titanium and vanadium impurities decreased from 15 and 97 ppm to 1 and 6 ppm, with removal rates of 93.3% and 93.8%, respectively. Thermodynamic calculation results indicate that B undergoes spontaneous reaction with titanium and vanadium, forming TiB₂ and VB₂, which precipitate at the bottom, thereby explaining the observed decrease in impurities. This study provides ideas and data reference for the removal of titanium and vanadium impurities in aluminium matrix.