Liquid Aluminum Research Articles

Material efficiency at the component level: how much metal can we do without?

Global production of steel and aluminium is a major driver of greenhouse gas emissions. Various processes might allow continued primary production of the two metals, but all depend on emissions-free electricity or carbon storage, and global capacity of these two key resources will be below demand for decades to come. As a result, zero-emissions steel and aluminium will mainly come from recycling, but supply will be lower than demand. This motivates demand reduction, and for the first time, this article estimates the inefficiency in current metal use by component type. The results demonstrate that around 80% of steel and 90% of aluminium liquid metal produced today may be unnecessary. Around 40% of liquid steel and 60% of liquid aluminium are never used in final components as they are removed along the supply chain of manufacturing. Of the metal that enters final service, approximately one-third could be saved by avoiding component over-specification. A further third could be saved, where the properties of metal are not used to their limits. These results point to specific opportunities for innovation in design and manufacturing technology, of which the highest priority is to re-think the use of sheet metal in construction.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Architecture of a remelted layer with the nano-lamellar structure at the surface of Fe[sbnd]B materials via laser remelting to resist liquid aluminum corrosion

In this work, a significant enhancement of corrosion resistance of Fe-B materials in liquid Al (750 °C), with a corrosion rate one order of magnitude lower than that of H13 die steel, has been achieved by constructing nano-lamellar structures in the matrix. Results indicate that the nano-lamellar structure can not only effectively obstruct the interdiffusion between the Al and Fe atoms, restricting the growth of corrosion layers, but also accommodate sufficient growth and thermal stresses, suppressing the spallation of corrosion products. Furthermore, the ceramic nanoparticles in-situ formed in the nano-lamellar structure can inhibit the inward diffusion of Al atoms, greatly enhancing the corrosion resistance of α-Fe matrix. Besides, they also provide a robust pinning effect on the corrosion interface, improving the adhesion strength of corrosion products with the matrix. The architecture of nano-lamellar structure with nanoparticles may provide a novel strategy against liquid Al corrosion and shed new light on the development of corrosion-resistant materials.

Study on the wetting characteristics of liquid-Al/ SiO2 interface with Si content in liquid-Al

Aiming to address the issue of aluminum slag adhering to the interior walls of vacuum lifting ladles in the aluminum electrolysis industry, Molecular dynamics simulations are employed to investigate the wetting behavior and adhesion characteristics of aluminum droplets on silica surfaces. Our findings indicate that with an increase in silicon content within the droplets, wetting diminishes and complete wetting of the silica substrate by aluminum droplets is not achieved. The presence of silicon reduces both the melting point temperature and surface tension of aluminum droplets, leading to a significant increase in contact angle and a corresponding decrease in wettability. Moreover, an elevated silicon content within molten aluminum droplets substantially decreases their interaction energy with the substrate surface. The virtual wall method is applied to examine average separation force and work of separation for detaching aluminum droplets from the substrate, revealing that adhesion characteristics are predominantly governed by mutual adhesive forces. This paper presents an atomic-level analysis elucidating how silicon as an alloying element influences adhesion between liquid aluminum and solid surfaces.

Liquid Phase-Made Aluminum Nanoparticles and Their Hydrogen Sorption as Aluminum/LiH Composite

Liquid Phase-Made Aluminum Nanoparticles and Their Hydrogen Sorption as Aluminum/LiH Composite

Nanotechnology enabled casting of aluminum alloy 7075 turbines

Aluminum alloy 7075 is well-known for its high-performance structural systems due to its lightweight and excellent mechanical properties. However, its susceptibility to hot cracking and limited fluidity hinder its casting suitability, posing challenges in manufacturing near-net-shaped structures economically, especially for thin and intricate aerospace components. This paper presents experimental results based on nano-treating, an emerging nanotechnology-enabled manufacturing method by incorporating a low fraction of nanoparticles in liquid aluminum, to allow the casting of complex aluminum alloy 7075 parts. Vacuum fluidity tests demonstrated that nano-treating of aluminum alloy 7075 with only 0.5 vol% TiC nanoparticles increased the fluidity of aluminum alloy 7075 by more than 20%, effectively eliminating hot cracking and enhancing surface quality. Through the Rapid Investment Casting process, nano-treated aluminum alloy 7075 can be successfully cast into turbines with 0.5 mm thick blades. In contrast, aluminum alloy 7075 without nano-treating failed to produce good casting quality due to poor filling and severe cracks. The manufacturing trials highlight the significant improvement in castability achieved through nano-treating, opening a novel pathway for the cost-effective production of complex aluminum alloy 7075 structures for numerous 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.

Impregnation of Graphite with Aluminum under High Pressure

To impregnate graphite of the GMZ brand with liquid aluminum alloy D16, a high-pressure method and apparatus previously used for impregnating carbon frames with liquid coal pitch in the isostatic technology for the production of carbon-carbon composite materials were used. The graphite blank and the amount of aluminum alloy calculated from the initial porosity of graphite were placed in a thin-walled container, degassed in a vacuum furnace, after which the container with the contents was sealed. Thermobaric treatment was carried out at a temperature of 750°C and pressure of 100 and 200 MPa. After finishing the treatment, the density and porosity of the obtained metallographic composites, as well as their compressive strength, were determined. As a result of these thermobaric treatments, the density and compressive strength of the obtained composites increased significantly, and the porosity decreased markedly.

Molten Aluminum-Induced Corrosion and Wear-Resistance Properties of ZrB2-Based Cermets Improved by Sintering-Temperature Manipulation.

During the hot dip aluminum plating process, components such as sinking rollers, pulling rollers, and guide plates will come into long-term contact with high-temperature liquid aluminum and be corroded by the aluminum liquid, greatly reducing their service life. Therefore, the development of a material with excellent corrosion resistance to molten aluminum is used to prepare parts for the dipping and plating equipment and protect the equipment from erosion, which can effectively improve the production efficiency of the factory and strengthen the quality of aluminum-plated materials, which is of great significance for the growth of corporate profits. With AlFeNiCoCr as the binder phase and ZrB2 as the hard phase, ZrB2-based ceramic composites were prepared by spark plasma sintering (SPS). SEM, EDS and XRD were used to characterize the microstructure and properties of the sintered, corroded, and abraded material samples. The density, fracture toughness, corrosion rate and wear amount of the composite material were measured. The results show that ZrB2-AlFeNiCoCr ceramics have compact structure and excellent mechanical properties, and the density, hardness and fracture toughness of ZrB2-AlFeNiCoCr increase with the increase in sintering temperature. However, when the composite material is at 1600 °C, the relative density of the sintering at 1600 °C decreases due to the overflow of the bonding phase. Therefore, when the sintering temperature is 1500 °C, the high entropy alloy has the best performance. The average corrosion rate of ZrB2-1500 at 700 °C liquid aluminum is 1.225 × 10-3 mm/h, and the wear amount in the friction and wear test is 0.104 mm3.

Study on the Effect of Al-Ti-B-RE Refiner on the Refining Effect of A356 Aluminum Alloy after Different Melt Treatments

Abstract The A356 aluminum alloy treated with conventional flux purification and impurity removal flux purification was refined using Al-Ti-B-RE refiner. The aluminum liquid treated with impurity removal flux purification had a better refining effect, with a reduction in grain size of 25.26% and a significant improvement in strength and elongation. Due to the higher purity of the aluminum liquid purified by the impurity removal flux, the stability of the refinement effect is better maintained during the later insulation process, providing good conditions for the transportation and casting of the aluminum liquid.

Minitab 20 and Python based-the forecasting of demand and optimal inventory of liquid aluminum sulfate supplies

In a company, inventory management is crucial due to the significant impact on various aspects of the business. Similarly, the Indonesian water supply company (PDAM) requires effective inventory management to ensure the supply of liquid aluminum sulfate chemicals. The probabilistic statistical inventory control (SIC) model is commonly used for inventory management. However, previous research on chemical inventory models in PDAMs often relied on simple linear regression to forecast demand data, which fails to capture the inherent volatility in demand. Therefore, this research aimed to predict demand data using the seasonal autoregressive integrated moving average (SARIMA) method and determine the optimal policy for supplying liquid aluminum sulfate chemicals. The results showed that the best demand forecasting model was SARIMA (2,1,2) (1,1,0)12 with a mean absolute percentage error (MAPE) value of 8.19%. The finding of the optimal inventory policy showed a safety stock value of 11,922.35 kg, a reorder point value of 49,511.20 kg, and an order quantity of 21,526.59 kg, leading to a total cost of IDR 11,132,034,145.45. The sensitivity test also showed that variations in lead time, price, μ, and σ parameters directly influence changes in total cost, reorder point, and safety stock. These calculations were conducted using Minitab and Python software.

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.

The wettability of pure liquid aluminum on oxide substrates

AbstractOxide particles are considered to be one of the reasons for the stability of cellular porous Al foam. Thus, the contact angle (ө) of molten pure aluminum on oxide substrates, including Al2O3, CaO·2Al2O3 (CA2), CaO·6Al2O3 (CA6), mullite (3Al2O3·2SiO2), and SiO2 was measured in a vacuum heating microscope at a temperature of 950°C to determine the value of wettability of molten aluminum on various oxides. Thereafter, the measured contact angles followed the tendency as mullite (155°) > CA6 (152°) > MgAl2O4 (151°) > Al2O3 (149°) > SiO2 (124°) > CA2 (100°). Furthermore, the cross‐sectional area between molten aluminum and substrates was thoroughly analyzed, and the reaction products, such as the Al2O3 layer at the interface, have been detected. Thermo‐Calc, with the combination of available databases, was used to perform thermodynamic simulations and to discuss and predict possible reactions under the current experimental conditions.

Thin-walled aluminium waste remelting in circulation circuit with magnetodynamic pump

Modern technologies for remelting thin-walled aluminium waste are considered, and a new method to implement such process is proposed. This made it possible to increase the yield of a suitable remelted product to 83% from the mass of the initial remelting portion. The main idea is to use indirect heating of the charge. This will allow to significantly reduce the irreversible loss of metal due to burning which can reach 60%. In the proposed process, solid waste is melted by overheated melt stream. The movement of such stream is provided by the action of electromagnetic field. For the practical implementation of the offered idea, there was used a magnetodynamic pump (MDP) designed in the Physico-Technological Institute of Metals and Alloys of National Academy of Sciences of Ukraine. The MDP has a significantly higher heat and power factor than electromagnetic pumps of travelling magnetic field which are often used in similar technologies. Mathematical model of the remelting process of aluminium thin-walled and fine charge due to convective heat transfer was developed. On the basis of this model, an engineering calculation of the specific process of remelting used aluminium cans in the liquid aluminium stream was also carried out. The obtained results were used at further conducting a full-scale experiment. There is designed and successfully practically tested the experimental two-chamber circulation circuit with MDP for remelting thin-walled aluminium waste. Recommendations for further development of the proposed process were formulated.Graphical abstract

Arc erosion characteristics of cables with heatproof insulations in AC series circuits at low pressure

Abstract The droplet diameter, dripping frequency, and arc bead appearances vary significantly with pressure. This study investigated the arc erosion characteristics of copper-core cable with mica insulation (HC0) and aluminum-core cable with PI insulation (HA0) at different pressures. During arcing of HC0, the diameters of dripping droplets decrease as pressure decreases, but the dripping frequency exhibits an increasing trend. The primary arc beads (PABs) of HA0 at atmospheric pressure are mainly globular arc beads. HA0 PABs at 60 kPa are mostly coral arc beads, which is attributed to the slow oxidation rate and easier outflow of liquid aluminum through cracks at low pressure. HA0 PABs have the characteristics of coral arc beads and gradual necking, which broadens the previous theory in accident investigations that coral arc beads and gradual necking are considered as physical evidences of fire globules and short-circuit melted marks. Besides, the influence of pressure on arc duration of HC0 and HA0 is revealed. This study could provide support for fire accident investigation and arc accident prevention.

Conversion of Aluminum to Hydrogen: A Metallurgical Point of View

Transition to the Net‐Zero economy requires new sources of energy. Hydrogen is one of the promising candidates to replace carbohydrates. Emission‐free technologies for hydrogen production are pivotal for this transition. However, the existing technologies to produce hydrogen are either polluting or energy‐intensive. In recent years, a reaction of aluminum with water generating hydrogen has attracted a lot of attention. Most of the research is done with solid aluminum and analyzed mostly from the chemical and energy points of view. In this overview paper, rarely mentioned metallurgical aspects of this reaction are considered, as well as potential integration of the related technology into a green aluminum production cycle. The advantages of using liquid aluminum as well as related safety aspects are highlighted.

Unidirectional self-actuation transport behavior of metallic aluminum nanodroplets on SiO2/Fe surfaces

To address the issue of adhesion between liquid aluminum and the inner wall of the vacuum ladle during aluminum electrolysis production, molecular dynamics simulations are used to study the self-actuation behavior of aluminum droplets on the refractory materials SiO2 or Fe. Aluminum droplets are separated from the SiO2 surface by their self-actuation behavior in order to solve the issue of aluminum liquid adhesion to the inner wall. Furthermore, the impact of temperature, size, and wedge angle on the self-actuation behavior of droplets is investigated. The results show that droplet self-actuation is not possible when the droplet temperature is below 900 K. However, when the droplet temperature exceeds 900 K, the speed of droplet motion increases with the temperature rise. Within the radius range of 25 Å–32.5 Å, smaller droplet sizes are more advantageous for the self-actuation behavior of the droplets. The displacement of a droplet on a wedge-shaped wetting gradient substrate is significantly greater than on a rectangular wetting gradient. Additionally, the initial velocity of the droplet's motion increases with the wedge angle. However, a larger wedge angle leads to a decrease in the final displacement of the droplet. The results of the study will offer a new method to address the issue of adhesion between liquid aluminum and the inner wall of the vacuum ladle.

Research on hot cracking in laser welding of Al-contaminated CoCrFeMnNi high-entropy alloys

To study the thermal cracking susceptibility of laser-welded CoCrFeMnNi high-entropy alloys, stainless steel and aluminum alloy plates were each used as backing for welding. The microstructure of the weld and morphology of the fracture were examined. In addition, the chemical compositions of the fractures, the interfacial tension between the CoCrFeMnNi high-entropy alloy and liquid aluminum alloy, and the linear expansion coefficient of the CoCrFeMnNi high-entropy alloy were determined. The results show that when stainless steel is used as the base plate, no cracking is apparent in the weld, and the microstructure is made up of dendrites and equiaxed crystals. Conversely, when an aluminum alloy plate is adopted, solidification cracks are seen at the center of the weld, and the microstructure consists of bright polygonal dendrites scattered in a dark gray matrix. In the later stage of solidification, the contact angle between the Al-dominated low-melt liquid metal and the CoCrFeMnNi high-entropy alloy is about 14.6°, which is distributed in the form of a liquid film between the dendrite of the CoCrFeMnNi high-entropy alloy weld, and the linear expansion coefficient of the high-entropy alloy is 23 × 10−6-25 × 10−6 K−1 in the temperature range of 900–1100 K, which is higher than the thermal expansion coefficient of austenitic stainless steel in this range, and the solidification temperature range is 1000–1400K. Therefore, thermal cracks tend to occur during the solidification process.

Evaluation of Fe Content on the Fluidity of A356 Aluminum Alloy by New Fluidity Index

AbstractElements that are deliberately added to aluminum alloys or are incorporated into the alloy later depending on the production process affect the final product properties. In addition, liquid metal cleaning is important in minimizing undesirable elements. Considering the production process, one of the most harmful impurities that is likely to pass into the alloy via diffusion for aluminum is the element, Fe. It is known that this is due to the fact that although Fe is highly soluble in liquid aluminum and its alloys, it has very little solubility in solids. Depending on the Fe content, mechanical properties, porosity and fluidity properties are affected in aluminum alloys. In this study, stainless and carbon steel rods were dipped into the melt at 700 °C and 750 °C for 1, 2 and 5 h. Castings were performed before and after degassing. Four-channel fluidity mold with different section thickness was used in the trials. Additionally, microstructure characterization was performed under varying casting conditions. Fluidity Index was proposed which is a single value measured from all fluidity values in different sections. When the results were examined, it was determined that the diffusion material, holding time, casting temperature and liquid metal cleanliness had an effect on the fluidity. Due to the increase in diffusion time, a decrease in fluidity was observed in both carbon steel and stainless steel. It was found that fluidity was significantly reduced when using stainless steel.

Effect of Ti3AlC2 addition on the densification and high- temperature erosion resistance of TiB2 composite ceramics fabricated by SPS

TiB2-Ti3AlC2 composite ceramics were fabricated by spark plasma sintering (SPS) technique. The effects of Ti3AlC2 additive on the densification, mechanical properties and resistance to high-temperature aluminum liquid erosion of composite ceramics were investigated, and the mechanisms of densification and erosion resistance were highlighted, respectively. At sintering temperature of 1800 °C, pressure of 40 MPa, and holding time of 10 min, TiB2 composite ceramic with 40 wt% Ti3AlC2 acquired 98.9 % densification, 98.2 % thermal shock resistance, and 13.71 MPa∙m1/2 fracture toughness. The in-situ decomposition of Ti3AlC2 was clearly observed during the sintering process, and the generated liquid Al induced the liquid phase sintering mechanism, promoting the densification of composite ceramics. Besides, the simultaneous in-situ generation of TiC phase strengthened the TiB2 matrix and induced a mixed toughening mechanism of transgranular fracture and intergranular fracture, resulting in superior mechanical properties and better resistance to high-temperature erosion of TiB2-Ti3AlC2 composite ceramics.

Wettability and reactivity of liquid aluminium and highly deformed steel

The high-temperature liquid Al - solid S355J2N steel interaction was studied using a modified wettability test. A sessile drop method with a capillary purification procedure was employed for the first time, involving non-contact aluminium isothermal heating followed by the dropping of a pure liquid Al drop onto the severely deformed steel substrate and isothermal contact heating of Al with steel. The calculated contact angles and wetting kinetics curves demonstrated a good spreading and wetting of the investigated system. Scanning electron microscopy investigations played an important role in interpretation of the microstructural characteristics of the specimen, especially those located at the drop/substrate interface. The electron backscattered diffraction measurements allowed to characterize the microstructure of the interface zone to obtain more detailed information about the grain size, type of the intermetallic phases: θ-Al13Fe4, Fe2Al5, FCC Al and ferrite and their distribution in the neighborhood of the interface zone. These intermetallics were also confirmed via transmission electron microscopy studies coupled with energy-dispersive X-ray spectroscopy analysis of the drop/substrate interface. Research findings provide valuable insights into the liquid Al and steel interaction during the explosive welding process, where the local melting of metal takes place at the interface of colliding plates, strongly deformed due to the collision.