Al Alloy Research Articles

Grain Microstructure in Friction-Stir-Welded Dissimilar Al/Mg Joints of Thin Sheets with/without Ultrasonic Vibration.

Electron backscattered diffraction (EBSD) characterization was conducted on the typical regions in friction-stir-welded dissimilar Al/Mg joints of 2 mm thick sheets with/without ultrasonic assistance. The effects of ultrasonic vibration (UV) on the grain size, recrystallization mechanisms, and degree of recrystallization on both sides of the Al-Mg bonding interface and the intermetallic compounds (IMCs) were investigated. It was found that on the Mg side of the weld nugget zone (WNZ), the primary dynamic recrystallization (DRX) mechanisms were discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), with geometric dynamic recrystallization (GDRX) playing a secondary role. On the Al side of the WNZ, CDRX was identified as the primary mechanism, with GDRX as a secondary contributor. While UV did not significantly alter the DRX mechanisms in either alloy within the WNZ, it promoted the aggregation and rearrangement of dislocations. This led to an increase in high-angle grain boundaries (HAGBs) and an enhanced degree of recrystallization in the welds. The average grain size in both the Al and Mg alloys of the WNZ followed a pattern of initially increasing and then decreasing along the thickness direction, reaching a maximum in the upper-middle part and a minimum at the bottom. The influence of UV on the average grain size in the WNZ was minimal, with only slight grain refinement observed, and the minimum refinement degree was only 0.9%. The Schmid factor (SF) on the WNZ and thermo-mechanically affected zone (TMAZ) boundary regions of the advancing side (AS) indicates that the application of UV increased the likelihood of basal slip and extension twinning in the crystal structure. In addition, UV reduced the thickness of IMCs and improved the strength of the Al-Mg bonding interface. These results suggest a higher probability of fracture along the TMAZ and WNZ boundary on the AS when UV was applied.

Implications of nanomaterials reinforcement along with sub-zero temperature cooling on microstructure and mechanical properties of friction stir processed Al7075 alloy

Al 7075 surface composites (SCs) successfully fabricated with additive three different nano-scale particles multi-walled carbon nanotubes (MWCNTs), graphene (GNP), and titanium dioxide (TiO2) by friction stir processing (FSP). The consecutive two-pass FSP was executed under a controlled cooling environment at −20 °C with methanol pumped beneath the workpiece in a specially designed fixture. All of the SCs exhibited homogenous dispersion of filler nanoparticles in their microstructures. The grain size of SCs was remarkably reduced from that of the substrate. The enhancement in hardness and strength was ascribed fundamentally to the grain refinement and Zener (pinning) effect expedited by coolant circulation. The effect of second phase matrix on grain evolution and precipitate-intermetallics formed after FSP was characterized by scanning electron microscope (SEM) and XRD pattern. It has been recorded that there is around 95–110% increase in hardness values in SCs. The wear rate is also dropped in SCs owing to enhanced hardness and the formation of lubricating coating in the case of carbonaceous composites.

Easily Applicable Superhydrophobic Composite Coating with Improved Corrosion Resistance and Delayed Icing Properties

Mitigating the adverse effects of corrosion failure and low-temperature icing on aluminum (Al) alloy materials poses significant research challenges. The facile fabrication of bioinspired superhydrophobic materials offers a promising solution to the issues of corrosion and icing. In this study, we utilized laboratory-collected candle soot (CS), hydrophobic fumed SiO2, and epoxy resin (EP) to create a HF-SiO2@CS@EP superhydrophobic coating on Al alloy surfaces using a spray-coating technique. Various characterization techniques, including contact angle meter, high-speed camera, FE-SEM, EDS, FTIR, and XPS, were employed to investigate surface wettability, morphologies, and chemical compositions. Moreover, a 3.5 wt.% NaCl solution was used as a corrosive medium to evaluate the corrosion resistance of the uncoated and coated samples. The results show that the capacitive arc radius, charge transfer resistance, and low-frequency modulus of the coated Al alloy significantly increased, while the corrosion potential (Ecorr) shifted positively and the corrosion current (Icorr) decreased by two orders of magnitude, indicating improved corrosion resistance. Additionally, an investigation of ice formation on the coated Al alloy at −10 °C revealed that the freezing time was 4.75 times longer and the ice adhesion strength was one-fifth of the uncoated Al alloy substrate, demonstrating superior delayed icing and reduced ice adhesion strength performance.

Study of Helium Irradiation Effect on Al6061 Alloy Fabricated by Additive Friction Stir Deposition

Additive friction stir deposition (AFS-D) is considered a productive method of additive manufacturing (AM) due to its ability to produce dense mechanical parts at a faster deposition rate compared to other AM methods. Al6061 alloy finds extensive application in aerospace and nuclear engineering; nevertheless, exposure to radiation or high-energy particles over time tends to deteriorate their mechanical performance. However, the effect of radiation on the components manufactured using the AFS-D method is still unexamined. In this work, samples from the as-fabricated Al6061 alloy, by AFS-D, and the Al6061 feedstock rod were irradiated with He+ ions to 10 dpa at ambient temperature. The microstructural and mechanical changes induced by irradiation of He+ were examined using a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and nanoindentation. This study demonstrates that, at 10 dpa of irradiation damage, the feedstock Al6061 produced a bigger size of He bubbles than the AFS-D Al6061. Nanoindentation analysis revealed that both the feedstock Al6061 and AFS-D Al6061 samples have experienced radiation-induced hardening. These studies provide a valuable understanding of the microstructural and mechanical performance of AFS-D materials in radiation environments, offering essential data for the selection of materials and processing methods for potential application in aerospace and nuclear engineering.

Tailored porosity in additive manufacturing of 7075 aluminum alloy for crack suppression and high strength

Laser-directed energy deposition (LDED) additive manufacturing of 7075 aluminum (Al) alloy is highly challenging due to the inherent poor printability and high cracking tendency. Here, we disclose a new approach to suppress cracking in LDED-processed 7075 Al alloy by engineered porosity (about 1.14 %). The crack-free 7075 Al alloy was achieved by slightly sacrificing the densification. Further increasing the density of the material by increasing laser energy input leads to cracking. The mechanisms of minor pores in alleviating cracks are mainly reflected in three aspects: (i) pores disrupt the epitaxial growth of columnar grains; (ii) free-form surfaces surrounding pores could release the accumulated residual stress, and (iii) more dislocations near pore drive nucleation of near equiaxed grains. The LDED-processed crack-free 7075 Al alloy after heat treatment shows an ultimate tensile strength of 464 ± 12 MPa and break elongation of 9.7 ± 1.2 %, attaining a good strength-ductility synergy among many additively manufactured 7075 Al alloys in the current literature. Unlike the mainstream additive manufacturing of metallic materials, which pursues high densification to attain high-performance components, this work demonstrates the positive roles of pores in the additive manufacturing of cracking-sensitive materials. The findings of this work highlight new insights regarding the balance between pores and cracks for better manufacturability and higher mechanical performance of materials.

Tensile strength and strain energy absorption in twist extruded Al 6061-B4Cp metal matrix composites

ABSTRACT Due to its accessibility and ease of use in various sectors, the twist extrusion method is gaining significant acceptance for improving the strength and hardness of structural components. However, only a few experiments on twist-extruded MMCs of aluminium 6061 alloy reinforced with ceramic boron carbide (B4C) particles have been reported. The development of an Al-6061 alloy reinforced with 1.5–8 weight percent B4C particles and its twist extrusion, a severe plastic deformation method, are the main subject of this work. The study aimed to investigate the influence of particles and the extrusion process on the tensile strength and specific strain energy absorption of both the matrix and the composites. It was observed that the addition of B4C particles and the extrusion process increased the hardness and tensile strength of the alloy by 29.1% and 68.3%, respectively and for the composites with 8 wt.% particles, the increases were 31.8% and 62%, respectively. However, the theoretical density, ductility and absorbed strain energy decreased by 3.97%, 35.7%, and 27.9%, respectively, for the composite with 8% B4C, compared to the extruded matrix. A microscopic study determined the ASTM grain size number, which supported the observed physical and mechanical properties of both the as-cast and twist-extruded Al 6061-B4Cp composites.

Electroplasticity constitutive modeling of aluminum alloys based on dislocation density evolution

Electrical current can effectively improve the plasticity of metallic materials. The tensile deformation behavior of Al alloys under the pulsed electrical current assisted quasi-static unidirectional tension (EAT) has been investigated. Materials under the EAT exhibits periodic electro-softening and strain-hardening behaviors, i.e., a ratchet shape mechanical response. However, establishing a constitutive model to accurately predict the ratchet shape mechanical behavior, especially during the EAT interval, and accurately predicting the strain-hardening behavior of materials are critical issues that need to be solved urgently. In this study, based on the Taylor polycrystalline model, thermal activation theory and dislocation density evolution theory, a two-parameter dislocation density electroplasticity constitutive model with forward and reverse dislocation density evolution was developed to describe the periodic coupling effect of the electro-thermal-mechanical fields during EAT. The tensile deformation behaviors of AA 6061-T6 and AA 7075-T6 under the effect of a pulsed electrical current were quantitatively predicted using the proposed constitutive model. The results show that the correlation coefficient between the predicted and experimental results of the constitutive model can reach 0.84–0.99, implying that the proposed constitutive model can accurately predict the complex electroplasticity behavior of Al alloys during EAT.

Microstructural evolution and deformation mechanisms of superplastic aluminium alloys: A review

Aluminium alloy is one of the earliest and most widely used superplastic materials. The objective of this work is to review the scientific advances in superplastic Al alloys. Particularly, the emphasis is placed on the microstructural evolution and deformation mechanisms of Al alloys during superplastic deformation. The evolution of grain structure, texture, secondary phase, and cavities during superplastic flow in typical superplastic Al alloys is discussed in detail. The quantitative evaluation of different deformation mechanisms based on the focus ion beam (FIB)-assisted surface study provides new insights into the superplasticity of Al alloys. The main features, such as grain boundary sliding, intragranular dislocation slip, and diffusion creep can be observed intuitively and analyzed quantitatively. This study provides some reference for the research of superplastic deformation mechanism and the development of superplastic Al alloys.

Al(Si)/Al2O3 and NiAl(Si)/Al2O3 co-continuous composites obtained by low temperature Reactive Metal Penetration of dense silica preforms.

Interpenetrating network Al(Si)/Al2O3 composites, obtained by a reactive metal penetration process, where pure aluminum metal reacts with a dense amorphous silica preform, are an interesting class of metal/ceramic composites, with two continuous networks of metal (Al-Si alloy) and ceramic (Al2O3). These composites have high stiffness and hardness, while retaining acceptable toughness and good thermal and electrical conductivity, and can be used in wear or thermal management applications. A second infiltration step with nickel allows to substitute the Al(Si) alloy with an intermetallic, obtaining an interpenetrating network NiAl(Si)/Al2O3 composite, with very high hardness and melting point. While in the standard process the temperature for obtaining the Al(Si)/Al2O3 composites is in the 1100-1200 °C range, in this paper we studied instead the 700-1000 °C temperature range and its effect on the microstructure of the final NiAl(Si)/Al2O3 composite. After the first infiltration step, the microstructure of Al(Si)/Al2O3 composites depends on both temperature and time of the treatment. At 700-800 °C and for reaction time of 1-2 hours, the grain size is completely sub-micrometric. When temperature and time of reaction increase, islands with a coarser microstructure, of micrometric size, form, reaching a fully micrometric coarser microstructure at 1100-1200 °C. The islands formation is due to the transformation from transition aluminas, formed at low temperature and low reaction time, to α-alumina, while at high temperature α-alumina forms directly. In a second step, the Al(Si) metal network was replaced with an intermetallic one, by contacting the composite with liquid nickel, that reacted with the Al(Si) alloy forming an Al-Ni-Si intermetallic. The temperature and duration of the first infiltration step strongly influences not only the microstructure of the Al(Si)/Al2O3 composite but also of the final NiAl(Si)/Al2O3 one, that is finer when the first step (reaction of aluminum with silica) occurs at lower temperature.

Effect of dimensional stabilization treatment on mechanical properties of 45% SiCp/Al composites

Abstract With 14μm SiC particles and 2024Al alloy as raw materials, 45% SiCp/Al composites were prepared by hot isostatic pressing method to study the effect of dimensional stabilization treatments on the mechanical properties of composites. The dimensional stabilization treatments used were divided into annealing heat treatment and cold and thermal cycle treatments, and the research method found that the primary annealing treatment decreased the bending strength from 694MPa to 639MPa, and the secondary annealing treatment decreased the bending strength from 863.69MPa to 605MPa. The bending strength decreased from 694 MPa to 639 MPa after the second annealing treatment, and further to 605 MPa after the second annealing treatment. The bending strength of the composites also decreased from 863.69 MPa to 836.16 MPa, and then to 855.54 MPa after solution aging due to the cold and thermal cycle treatments of 120°C to −20°C and 190°C to −196°C, respectively. The micro yield strength increased from 356.57 MPa to 402.66 MPa, and then to 476.03 MPa. The dimensional stabilization treatments included heat treatment, as well as cold and thermal cycle treatments. The cold and thermal cycle treatments further increased the brittleness of the composites after solution aging. Both annealing and cold and thermal cycling reduce the density of the composite, with the annealing resulting in a smaller reduction than the cold and thermal cycling.

Dispersoid evolution in Al–Zn–Mg alloys by combined addition of Hf and Zr: A mechanistic approach

Coherent Al3X-type L12-structured dispersoids have the potential of effectively stabilizing the grain structure and increasing strength. This concept has been successfully demonstrated for non-hardenable and rapidly solidified Al alloys. In precipitation-hardened Al alloys, effective dispersoid addition requires both controlling their high-temperature stability and minimizing their impact on precipitation hardening. The current study focuses on dispersoid-modified AlZn5.0 Mg1.2 alloys, which exhibit MgZn precipitation upon age-hardening and include less than 1 wt% of Zr and Hf for dispersoid formation. Heat treatments between 350 °C and 500 °C for varying times were applied to evaluate dispersoid formation, thermal stability and the related strengthening potential. The microstructure was assessed using transmission electron microscopy (TEM) and atom probe tomography (APT), and the mechanical response was evaluated by hardness testing. TEM after heating at 500 °C reveals Ostwald ripening for the dispersoids. APT results on the dispersoids reveal a core–shell structure development upon longer annealing times. The Zr–Hf-modified alloy exhibits a higher initial strength than the Zr-modified alloy but the latter displays greater strength retention even after prolonged exposure to 500 °C. This effect is attributed to a destabilization of the mixed Zr–Hf dispersoids that arises from lower enthalpic benefits of Al3Hf formation over Al3Zr.

PDA-modified sol-gel coating for long-lasting corrosion protection on Al alloy 3003

Within the realm of corrosion protection methods for Al alloys, sol-gel technique has garnered increasing attention. However, conventional sol-gel methodologies cannot provide adequate long-lasting corrosion protection to Al alloys when exposed to chloride-rich solutions. This paper introduces an innovative approach to substantially augment the corrosion resistance of aluminum alloys through utilization of polydopamine (PDA)-modified sol-gel films. Effort was made to fabricate a PDA-modified sol-gel coating and a systematic investigation was conducted thereof. Long-term corrosion performance of this coating in 3.5 wt.% NaCl solution was evaluated through electrochemical impedance spectroscopy (EIS). Results show that the low-frequency impedance of the PDA-modified sol-gel coating remains significantly high at 7.9 × 105 Ω·cm2, even after 36 d of immersion in 3.5 wt.% NaCl medium, indicative of excellent protective properties. It notably surpasses low-frequency impedance of the unmodified coating, which registers at 2.5 × 104 Ω·cm2. The incorporation of PDA into the sol-gel coating, facilitated by adsorption and diffusion mechanisms, serves to fill micrometer- and nanometer-scale defects of the coating, thereby markedly enhancing their compactness. Furthermore, despite its modest thickness of 9 μm, the PDA-modified coating exhibits enduring corrosion protection capabilities.

Electrolyte Solution Stirring Effect on Deposition Rate, Crystallographic Orientation, and Electrochemical Behaviour of Ni Film

Abstract Stirring the electrolyte meanwhile electrodeposition process is running may influence the properties of the forming films. In this work, the electrodeposition of copper (Cu) over aluminium (Al) alloy was performed. Subsequently, the electrodeposition of nickel (Ni) onto the formed Cu layer was conducted. In order to enhance the films properties, some various stirring speeds then are implied on the plating solution of the Ni electrodeposition process. The synthesized of Ni films were analysed by means of both X-ray diffraction (XRD) and a potentiostat equipment. The sample made shows different physical properties before and after electrodeposition based on sample weighed to examine the deposition rate. XRD patterns confirmed that all samples have a face-centered cubic (fcc) crystal structures with a space group of Fm-3m. Stirring speed play an important role of an inverse relationship with deposition rate, crystallite size, lattice strain, and corrosion rate. The sample that was made using the highest stirring speed yield a better corrosion resistance at around 0.239 mmpy due to less lattice strain.

Enhancing wear resistance of aluminum 6061 composites with fly ash: A sustainable approach for industrial applications

This study investigated the benefits of adding fly ash as a reinforcement material. The benefits included cost-effectiveness, improved quality, isotropic behavior, and environmental advantages. To improve self-lubrication and wettability behavior, Al6061 alloy composites were fabricated with different amounts of fly ash (0%, 2%, 4%, 6%, and 8% by weight), along with a fixed amount of graphite (3wt.%) and magnesium (2wt.%). Wear tests were conducted using Taguchi’s Design of Experiment (DoE) approach on the composites. The optimized composition with 6% fly ash exhibited the least wear rate under the test conditions of load = 10 N, sliding velocity = 3 m/s, and sliding distance = 2 km. SEM images revealed a uniform distribution of fly ash and graphite reinforcement in the matrix, contributing to enhanced wear resistance. The composites exhibited fewer scratches and plastically deformed surfaces, indicating a decrease in wear rate and increased wear resistance with higher fly ash content. ANOVA were used, and four parameters were identified to be critical, Composition at 34%, Sliding Distance at 27%, load at 23%, and Sliding Velocity at 12% contribution with a statistical confidence of 95%. This research contributes to developing cost-effective and environmentally sustainable materials with improved mechanical properties. It makes them suitable for various industrial applications, such as the automotive industry, where wear resistance is essential.

Toolpath and Tool Design Innovations in Deformation Machining for Superior AA-7075 T6 Fins

Abstract A hybrid manufacturing process, deformation machining (DM) combines subtractive manufacturing with incremental forming. Monolithic components with complex profiles are created through the hybridization of manufacturing technologies, which also reduces the wastage of raw materials. The properties of geometry and surface quality of the fin made from the aluminum alloy Al-7075 T6 using the DM process’s bending mode was examined in this research, as were the effects of various approaches, toolpath methods, and tool design. To achieve the desired shape for the machined fin, various combinations of arcuate and slanting fin toolpath techniques were explored utilizing both top-down and bottom-up methods. The bottom-up method and the arcuate toolpath strategy were used to investigate various tool profiles. Using the best combination of toolpath strategy and tool profile, named as the T3 tool profile, which has a 0.6 mm nose radius and a circular sector, bottom-to-top (BTT)technique, and arcuate toolpath method, components with better geometrical features and surface roughness (SR) were produced. The analysis of the forming force in the bending approach of the DM progression was further carried out using this optimal combination.

Microstructure and strength-conductivity synergy of Al-Mg-Si-Cu alloy sheets prepared via vacuum melting and thermo-mechanical treatment

This work has investigated the response of microstructural evolution on the strength and electrical conductivity (EC) of vacuum melted Al-Mg-Si-Cu alloys during T6 heat treatment, cold rolling (CR) and re-aging (RA). The precipitation behavior of nano-scaled precipitates during thermo-mechanical treatment was revealed. The strength- conductivity improvement mechanisms of the alloy were discussed. The results showed that compared with the non-vacuum melting alloy, there were superior enhancements in the strength and EC of the alloy prepared by vacuum melting due to the high compactness. After T6 heat treatment, nanoscale β", Q' and L phases were precipitated in the alloy sheet. Owing to the increased dislocation density and precipitate dissolution during CR, the strength of the alloy sheet was improved, followed by a decrease in EC. After RA, a good combination of strength and EC of the alloy sheet was obtained, i.e., ultimate tensile strength and EC were 350MPa and 57.48% IACS, respectively, which was associated with the formation of nano-sized precipitates and the decrease in solute atom concentration. The precipitates volume, dislocation density, grain refinement and solid solubility during thermo-mechanical treatment were the main factors determining the strength and EC of the alloy. This work provides a strategy for the preparation of high strength-conductivity Al alloys.

Development of Automotive and Marine Appliable Aluminium Composite by Utilizing Agro-Waste Material as Performance Enhancement Particles

Aluminium-based materials are lightweight materials used for producing automotive and aircraft components. However, aluminium materials diminish in performance on exposure to degrading environments, which limits their areas of usage and applications. The degrading effect results in poor resistance to wear and corrosion, reduced properties and defective microstructure. In this work, 6063 aluminium alloy was reinforced with particles of agricultural waste (walnut shell) to produce six samples with five samples of reinforced and a control (unreinforced) sample. Each of the samples of the reinforced alloy was moulded into a 25 mm diameter by 130 mm height using the stir casting method using an industrial pit furnace. The samples were thereafter machined to a diameter of 20 mm and cut into a thickness of 10 mm for characterizations. The potentiodynamic polarization method was used to test for the samples’ corrosion resistance properties following the ASTM G102 standard in 3.65% NaCl test medium. The hardness property was investigated using the Brinell hardness machine following the ASTM A-370 standard, while the microstructure and crystallographic phase studies were carried out using SEM/EDS and XRD profiles, respectively. The unreinforced 6063 Al alloy sample exhibited the highest corrosion rate (Cr) of 0.7321 mm/year and the lowest hardness of 104.94 kgf/mm2. The 10% wt. walnut shell particles (WSP) reinforced 6063 Al alloy sample exhibited the lowest corrosion rate (Cr) of 0.1336 mm/year and the highest hardness of 109.24 kgf/mm2. This indicated that the walnut shell particles enhanced the corrosion and indentation resistance of the alloy. In addition, the SEM images indicated that the agricultural waste (walnut shell particles) reinforced samples exhibited more refined microstructure, lower porosity and smoother morphology compared to the unreinforced (control) sample. Also, the XRD profile of samples revealed some high peak intensity crystallites such as Al(ZnS), Al2O3 and (FeMn)SiO2. These high peak intensity crystallites indicated that these reinforced samples possessed chemical and microstructural homogeneity, high stability and good surface texture.

Gradient structured Al alloy with a synergistic improvement of strength-ductility obtained by friction stir processing

One Al 6061 with gradient microstructure is prepared by friction stir processing (FSP). Microscopic characterization indicates that the regulation of grain size gradient could be achieved by adjusting the process parameters of FSP. The mechanical property test indicates that one gradient Al 6061 combines an ultimate tensile strength of 266 MPa with a uniform elongation of 27 %, and the other comes 258 MPa with 29 %, which provides an excellent combination of strength and ductility. Moreover, the molecular dynamics (MD) method is employed to reconstruct and simulate the mechanical behavior of the gradient region and the dynamic evolution of the microstructure. When the stacking faults (SFs) with antisymbolic Burgers vector meet and detwinning occurs, grain refinement will induce localized strengthening. When the Shockley partials occur cross-slip, numerous sessile dislocations obstruct the dislocation motion more facilitate strain hardening. Meanwhile, a unique interaction mechanism between shear bands (SBs) and intergranular cracks in Al 6061 is discovered in plastic deformation. The coarse net-like SBs in the small-grain region are highly susceptible to catastrophic fracture of the material, and the large cracks formed within the severely band-like SBs in the large-grain region weaken the strength substantially. However, the formation of sessile dislocations in the gradient region effectively mitigates strain localization and inhibits the nucleation of large cracks. The results interpret the dynamic evolution process of gradient microstructure prepared by FSP and the mechanism of strengthening and toughening and provide process and theoretical references for the research and development of new engineering materials.

Inhibition of microbiologically influenced corrosion of Al alloy 5083 in the presence of Pseudomonas aeruginosa by Artemisia annua L

Microbiologically influenced corrosion (MIC1MIC, Microbiologically Influenced Corrosion1) of Al 5083 caused by P. aeruginosa was inhibited by A. annua aqueous extract (AAE2AAE, A. annuaAqueous Extract.2). Electrochemical measurements revealed that the adsorption of AAE on the electrode surface protected Al 5083 from MIC in a simulated marine environment with inhibition efficiency of 78 %. The adsorption layer was formed due to ionized chlorogenic acid interacting with charged Al 5083 surface, preventing bacterial adhesion and growth. Adding AAE promoted the formation of a protective Al2O3, and decreased the surface layer porosity. The pitting corrosion reduced considerably when AAE was added to biotic seawater, supporting the ICP-OES results.

Overview on aluminium alloys as sinks for end-of-life vehicle scrap

Abstract A fundamental principle in metallurgy is that the higher the purity of metals and alloys, the more favourable their properties will be. However, as the recycling of materials in production becomes increasingly significant, the levels of impurities are also on the rise. In the case of aluminium, the consequences can be detrimental due to the low solubility of most elements in this metal, which leads to the formation of brittle intermetallic phases (IMPs). Moreover, once impurities have entered aluminium, it is difficult to remove them. In 2017, almost 100 million cars were produced worldwide. Historically, vehicle design prioritised performance, resulting in a multi-material mix to utilise the best materials for each application. This included over 40 different wrought and cast aluminium alloys, Cu-based materials for electrics, and steels for high-strength applications. In the recycling of end-of-life vehicles (ELVs), high purity wrought Al alloys are today down-cycled to low purity cast engine blocks. However, recent advancements show that the drawback of increase IMP-fractions can be turned into benefits through the strategic design of heterostructured alloys. A first successful alloy example from this approach enables interesting forming properties, previously only found in 5xxx series wrought aluminium alloys, in combination with a matrix composition and age-hardening potential known from 6xxx series wrought aluminium alloys. A second examples reviews compositions directly resulting from ELV scrap. By manipulating IMPs it is feasible to create heterostructures with an interesting balance of strength and ductility. These approaches challenge traditional views, allowing for a greater volume fraction of intermetallic phases. Understanding the formation and role of intermetallic particles is crucial. This work gives an overview to the current problem and the state of the art and addressed the potential of upcycled aluminium alloys that tolerate high impurity levels by using intermetallic phases as impurity sinks.