Upcycled High-Strength Aluminum Alloys from Scrap through Solid-Phase Alloying

Upcycled High-Strength Aluminum Alloys from Scrap through Solid-Phase Alloying | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Letter Upcycled High-Strength Aluminum Alloys from Scrap through Solid-Phase Alloying Xiao Li, Tianhao Wang, Zehao Li, Tingkun Liu, Xiang Wang, Arun Devaraj, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4011560/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Dec, 2024 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract 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 novel 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 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 offers a new paradigm of metals reuse, with the option for on-demand upcycling of a variety of metallic materials from scrap sources. Physical sciences/Materials science/Structural materials/Metals and alloys Physical sciences/Engineering/Mechanical engineering Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Main Aluminum (Al) stands as the most extensively utilized non-ferrous metal globally [ 1 , 2 ], and the Al industry contributes 3% of all greenhouse gas emissions [ 3 ]. This is because the Hall–Héroult process used to produce primary Al from ore emits a significant amount of CO 2 [ 4 ]. Using 100% scrap aluminum feedstocks could theoretically reduce energy and carbon emissions by up to 95% compared to primary aluminum production [ 5 , 6 ]. Nevertheless, this level of reduced environmental impact has not been achieved because scrap inevitably contains undesirable impurities, requiring the addition of primary Al in a process known as “purifying and diluting” [ 3 , 7 – 10 ]. Also, the traditional production of secondary Al through recycling involves a number of energy-intensive steps ( Fig. 1 a). The reliance on primary Al additions, combined with the requirement for high-temperature melting and other processing steps, results in a recycled product that still has a relatively high energy and carbon intensity [ 3 ]. In this letter, we report friction extrusion as a solid-phase alloying method to both recycle and upcycle Al scrap to directly produce high-performance Al wrought extrudate in a single step, with a much lower carbon footprint (Fig. 1 b). For upcycling, 6063 Al scrap and alloying sources—copper (Cu) powder, zinc (Zn) powder, and ZK60 magnesium (Mg) ribbon—are first physically blended and then subjected to friction extrusion, removing the requirement for bulk melting to incorporate the alloying elements into the Al matrix. The thermo-mechanical nature of the friction extrusion process results in the production of a fine-grained aluminum microstructure with a high-density of strengthening nanoclusters in the extruded product. Because this solid-phase process allows aluminum scrap to be upcycled into high-performance aluminum products without the need for either the addition of primary aluminum or melting, it has the potential to significantly reduce CO 2 emissions [ 11 , 12 ]. As previously described, the precursor materials used in this work (Fig. 2 a) include 6063 Al scrap, with alloying additions of Cu, Zn, and ZK60 Mg. The products of the upcycling process are benchmarked against a recycled 6063 alloy manufactured using the same friction extrusion approach. For the recycled alloy, cold compacted 6063 scrap was friction extruded to produce a void free, 5 mm diameter rod (Fig. 2 b). For the upcycled product, the mixture of 6063 scrap and alloying additions were friction extruded under similar process conditions to produce a void-free rod (Fig. 2 c) with a composition close to that of a standard 7075 Al alloy. The recycled rod has an average grain size of 43.1 µm, as shown in the electron backscatter diffraction-inverse pole figure (EBSD-IPF) map in Fig. 2 d. The upcycled rod, on the other hand, shows pronounced grain refinement, with an average grain size of 7.7 µm (Fig. 2 e). A comparison of the tensile stress-strain curves for the recycled 6063 Al alloy, the upcycled 6063 Al alloy, and a conventional wrought 6063 Al alloy (Fig. 2 f), highlights the pronounced increase in yield strength and ultimate tensile strength for the upcycled material. Specifically, upcycling results in a > 200% increase in both the yield strength (from 87 MPa to 263 MPa) and the ultimate tensile strength (from 147 MPa to 443 MPa), when compared to the recycled alloy. Examining the microstructural evolution during the upcycling process provides insight into the origins of the differences in mechanical properties between recycled and upcycled materials. Optical microscopy of the longitudinal cross-section of the extruded rod and remnant disc (scrap/powders mixture) from the upcycling process (Fig. 3 a ) reveals four distinct processing zones: an unprocessed region consisting of the compacted scrap/alloying additions (Zone A); a transition region (Zone B); a processed region (Zone C); and the extruded rod (Zone D). Process temperatures increase exponentially from Zone A to Zone C, where the highest processing temperature is reached, The colling process begins Zone D. In the present study no forced cooling was applied. Higher magnification scanning electron microscopy (SEM) images, combined with energy dispersive spectroscopy (EDS) maps, from Zones A–D are also included in Fig. 3 b. These images show that in Zone A, the 6063 Al scrap is surrounded by Zn powders, ZK60 Mg alloy ribbons, and Cu powders, which are tightly compacted. In Zone B, the alloying additions undergo severe shear deformation and are highly strained, elongated, and fractured. In Zone C, further refining promotes dispersion and diffusion of the alloying additions into the Al matrix, prior to extrusion. In Zone D the extruded product has similar microstructural features to those observed in Zone C. It is clear from these images that the additional alloying elements Zn, Mg, and Cu become progressively more homogeneously distributed in the microstructure as the material is processed from Zone A to B, to C, and finally to D. In other words, these alloying elements are refined and mixed into the Al matrix during the friction extrusion process that took less than a minute to complete, while the Al scrap was simultaneously consolidated into the extrudate [ 13 , 14 ]. These observations are supported by a hardness map (inset in Fig. 3 a ) , which shows the variation in hardness that results from the above described changes in microstructure. This type of microstructure evolution during friction extrusion has been reported in our previous work on the 7075 Al alloy system [ 15 ], and can be attributed to gradients in strain and temperature fields as the material is processed [ 16 , 17 ]. To confirm homogneity of the microstructure and chemistry of the upcycled and recycled rods, additional microscopy was conducted on both transvere and longitudinal cross-sections, with illustrative results provided in Fig. S1 (Supplementary Material Section 1). Hardness testing on the cross-sections of both recycled and upcycled rods reveals an average hardness of 43 HV for the recycled rod versus an average hardness 116 HV for the upcycled rod ( Fig. S2 , Supplementary Materials Section 2). Further microstructural characterization of the recycled and upcycled specimens pinpoints the reason for the substantial strengthening achieved as a result of the upcycling process. X-ray diffraction (XRD) (Fig. 4 a) indicates that Mg 2 Si is the dominant precipitate phase in the recycled material. In the upcycled material, η'/Mg(CuZn) 2 is present in addition to Mg 2 Si. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) reveals the presence of numerous Guinier-Preston (GP) zones along with several ordered precipitates within the Al matrix (Fig. 4 b). A high-magnification bright field (BF) image, also shown in Fig. 4 b, confirms that the structure of the ordered precipitates is consistent with that of the η' phase[ 18 , 19 ]. Interestingly, we also found evidence that reaction occurs between pre-existing Mg 2 Si particles and dissolved alloying elements Cu and Zn. As shown in Fig. 4 c, new phases (rich in Cu and Zn) form next to Mg 2 Si particles. High-resolution transmission electron microscopy reveals that the newly formed phases are amorphous Mg(ZnCu), with crystalline η' phase/Mg(CuZn) 2 within the amorphous phase. More detailed information is provided in Fig. S3 (Supplementary Material Section 3) Three-dimensional atom maps of Al, Zn, Mg, and Cu distributions in the upcycled sample (Fig. 4 d) reveal fluctuations in the Zn and Mg atom distributions within the Al matrix. The frequency distribution of the second nearest neighbor (2NN) distance ( Fig. S4a ) reveals the presence of clusters consisting of Zn, Mg, and Cu atoms. Figure 4 e shows various crystallographic poles observed from the desorption map of the Atom Probe Tomography (APT) dataset. The stacking of ( \(\text{11}\stackrel{\text{-}}{\text{1}}\) ) atomic planes are clearly resolved in the Al map along the [111] crystallographic pole (Fig. 4 f). The Mg, Zn, and Cu map (Fig. 4 g) shows spherical (green arrow) and elongated (red arrow) precipiates on the ( \(\text{11}\stackrel{\text{-}}{\text{1}}\) ) planes, which correspond to Guinier-Preston I (GPI) and GPII zones [ 20 – 22 ], respectively. The number density of the GP zones is calculated to be ~ 1.6 × 10 24 m − 3 ( Fig. S4b ). These results provide strong evidence that solid-phase alloying is achieved during the upcycling process. Typically, the development of GP zones within an Al matrix relies on two key factors: first, the matrix must be in a supersaturated solid solution state, usually achieved through a combination of solution heat treatment and rapid quenching. Second, there should be a low-temperature artificial aging [ 23 ] or room-temperature natural aging [ 24 ], during which GP zones nucleate and grow. However, subjecting the material to plastic deformation after attaining a supersaturated solid solution state can significantly expedite the aging process. This acceleration is attributed to dislocations generated during plastic deformation serving as nucleation sites for GP zone formation [ 25 , 26 ]. Recent research has demonstrated that continuous plastic deformation can facilitate the direct formation of GP zones without the need for further aging steps. For instance, cyclic deformation of a supersaturated aluminum alloy at room temperature results in the dynamic precipitation of solute clusters (GP zones) by continuously introducing vacancies into the matrix [ 27 ]. Similar observations have been made in supersaturated magnesium alloys, where equal channel angular extrusion generates excess vacancies, leading to solute segregation and direct GP zone formation [ 28 ]. In the current study, the precursor materials are not in a supersaturated condition. Consequently, we hypothesize that two processes occur essentially simultaneously during the upcycling process: (1) dissolution of alloying additions into the matrix to create a supersaturated solid solution, and (2) formation of GP zones due to the continuous generation of vacancies through severe plastic deformation. The disparity in strength between recycled and upcycled materials (Fig. 2 f ) arises from the observed microstructural variations which can activate various strengthening mechanisms, such as grain boundary strengthening, solid solution strengthening, dislocation strengthening, and precipitate strengthening. Differences in grain size contribute to the strength increase, specifically with \({\sigma }_{gb}\) (grain boundary strengthening) values of 43.2 MPa for upcycled materials and 13.1 MPa for recycled materials (refer to Supplementary Material Section 4 for detailed calculations). Alloying content variations also play a significant role in the strength difference, leveraging both solid solution strengthening and precipitate strengthening mechanisms. In particular, \({\sigma }_{ss}\) (solid solution strengthening) values for upcycled and recycled materials are 46.8 MPa and 7.4 MPa, respectively (detailed calculations in Supplementary Material Section 5). The assessment of precipitate strengthening relies on the 3D atom probe analysis findings depicted in Fig. 4 d. Notably, the presence of η’ precipitates is considered insignificant for strength calculations. However, the presence of GP zones has a significant effect. The 3D atom probe analysis provides details on the average size and volume fraction of GP zones in the upcycled specimen, with strength contributions ( \({\sigma }_{Orowan}\) ) from GP zones amounting to 115.9 MPa. Note that the strength attributed to GP zones (coherent to the Al matrix) is anticipated to result from a dislocation shearing mechanism ( \({\sigma }_{CS}\) ) rather than an Orowan dislocation bypassing mechanism ( \({\sigma }_{Orowan}\) ). However, the calculation revealing \({\sigma }_{Orowan}\) to be smaller than \({\sigma }_{CS}\) implies that Orowan dislocation bypassing is the operative mechanism for GP zones in this case. A comprehensive description of the calculation is provided in Section 6 of the Supplementary Material. It is crucial to note that the recycled specimen lacks GP zones, making the determined \({\sigma }_{Orowan}\) from GP zones in the upcycled specimen an indicative measure for the precipitate strength contrast between the recycled and upcycled specimens. The variation in dislocation density does not significantly influence the strength difference, with ( \({\sigma }_{d}\) ) (dislocation strengthening) values of 52.3 MPa for upcycled and 56.7 MPa for recycled specimens (refer to Supplementary Material Section 7 for detailed calculations). In total, theoretical calculations predict a yield strength improvement of 181 MPa in the upcycled aluminum, versus the recycled aluminum, in good agreement with the measured difference of 176 MPa. In summary, a high-performance Al alloy is obtained by upcycling 6063 scrap with copper, zinc, and magnesium in a single-step, solid-phase alloying process. The yield and ultimate tensile strength of the upcycled material is increased by > 200% compared to the recycled material, due primarily to the formation of GP zones. These results demonstrate that low-strength and low-cost Al alloy scrap can be upcycled to high-strength and high-value Al alloy products by incorporating alloying elements via scalable solid-phase processing (friction extrusion), without the need to melt the precursor materials. Severe shear deformation imposed during friction extrusion refines the alloy additions and facilitates their uniform dispersion in the Al matrix, leading to the formation of fine GP zones and η'/Mg(CuZn) 2 . Of larger significance, these results provide a first demonstration of a novel approach to alloy design and manufacturing that creates value from waste, reduces the energy footprint and environmental impact of metals production, and offers a pathway to entirely new alloys and composites that cannot be produced by conventional melt-based proesses. Methods Base materials and tooling 6063 Al alloy scrap, Zn powders, Cu powders, and ZK60 Mg alloy ribbons were used as feedstock materials in this study. The chemical compositions of the 6063 Al alloy and ZK60 Mg alloy are provided in Table 1 . A ZK60 Mg alloy was selected instead of pure Mg to avoid flammability issues. The chemical composition of the target 7075 Al alloy is also listed in Table 1 . Friction extrusion tooling was made of H-13 tool steel. Spiral grooves were machined into the die face to facilitate material flow into the extrusion orifice, with a diameter of 5 mm. Die temperature was measured during processing using a type-K thermocouple (TC) spot-welded approximately 0.5 mm back from the die face. Table 1 Nominal chemical composition of 6063 scrap, additional alloying powders and ribbons, mixed precursor, and standard 7075 [ 29 ]. Material Chemical composition (wt. %) Al Mg Si Zn Cu Fe Zr 6063 scraps Bal. 0.45 0.4 0.02 0.02 0.2 - Cu powders - - - - 100 - - Zn powders - - - 100 - - - ZK60 ribbons - Bal. - 5–5.5 - - 0.57 Mixed precursor Bal. 2.5 0.4 5.6 1.6 0.2 0.01 Standard 7075 Al Bal. 2.1–2.5 0–0.5 5.6–6.1 1.2–1.6 0–0.5 0 • Friction extrusion process The manufacturing process for the recycled and upcycled rods is illustrated in Fig. 5 . First, precursor scrap and alloying elements were weighed out according to the chemical compositions shown in Table. 1 . Based on the amount of 6063 scrap and the additional additives, the final weight percentages of Mg, Cu, and Zn in the upcycled material were approximately 2.5%, 1.6%, and 5.6%, respectively. Second, the precursor materials were loaded into a plastic bottle, and the bottle was sealed and placed on a roller mixer for 1 hour. Third, the premixed precursor was loaded into a billet container and cold compacted with ~ 110 MPa using a hand press. Then, the liner with the pre-compacted precursor was loaded for friction extrusion into a ShAPE™ machine manufactured by Bond Technologies. Critical friction extrusion parameters, such as starting and steady-state spindle speed and plunge speed are listed in Table 2 . Table 2 Critical friction extrusion parameters for recycling and upcycle processes. Process Starting material Spindle speed (RPM) Plunge speed (mm/min) Recycle 6063 Al alloy scrap From 300 to 100 From 6 to 4 and 2 Upcycle 6063 Al alloy scraps + Zn powders + Cu powders + ZK60 Mg alloy ribbons From 300 to 100 From 6 to 4 and 2 • Sample preparation Friction extrusion specimens were cut along the transverse cross-section and longitudinal cross-section using a diamond blade. Specimens for microstructural analysis were mounted in epoxy and polished to a final surface finish of 0.05 µm using colloidal silica. Three mini-tensile specimens were machined from the 5 mm diameter extruded rods for both the recycled and upcycled materials. The round bar specimens had a 38.1 mm total length and 15.88 mm gage length, following the ASTM-E8 standard. • Microstructural characterization Optical microscopy was performed using an Olympus BX-51 fluorescence motorized microscope. Scanning electron microscopy (SEM) was performed using a Thermo Fisher Scientific Quanta 200 focused ion beam (FIB)-SEM outfitted with an Oxford Instruments X-ray energy dispersive spectroscopy (EDS) system for compositional analysis. Electron backscatter diffraction (EBSD) was done using a Thermo Fisher Scientific Apreo 2S SEM with an Oxford Instruments EBSD detector operating at 20 kV and step size of 0.2 µm. The EBSD results were analyzed using ZtecCrystal EBSD processing software. Transmission electron microscopy (TEM) specimens were prepared by following the routine lift-out and thinning procedure of the FIB technique on a Thermo Fisher Scientific Quanta 200 FIB-SEM or a Thermo Fisher Scientific Helios 5 Hydra Dual Beam plasma focused ion beam milling scanning electron microscopy (PFIB-SEM). TEM/scanning TEM (STEM) observations were performed on an FEI (now Thermo Fisher Scientific) Titan 80–300 Environmental Cs-corrected TEM equipped with an EDS system. High-angle annular dark field (HAADF) and bright field (BF)-scanning transmission electron microscopy (STEM) images were captured on a JEOL GrandARM-300F operating at 300 kV with a convergence semi-angle of 29.7 mrad. The collection angles for HAADF-STEM were between 75 and 515 mrad. X-ray diffraction analysis was performed using a Rigaku D/Max Rapid II microdiffraction system. Diffraction data recorded on a two-dimensional image plate were integrated for diffraction angles between 20° and 150° using the manufacturer's software (2D Data Processing Software v.1.0, Rigaku, 2007). 3D atom probe (3DAP) analysis was performed using a local electrode atom probe (CAMECA LEAP 6000 XR) in voltage pulse mode with a pulse fraction of 20% at a temperature of 40 K. Sharp needle-like specimens for the 3DAP analysis were prepared by the FIB lift-out and annular milling techniques using an FEI Helios 5 Hydra UX. The statistics and chemistry of precipitates in the selected volume without the Al poles were analyzed using a maximum separation algorithm in the AP Suite ™ 6.3 software. The parameters of separation distances ( d max = 0.58), minimum number of solutes ( N min = 12), envelop distances ( L = 0.58), and erosion distances ( d erosion = L) were selected based on the nearest neighbor approach described elsewhere [ 30 ]. • Mechanical property characterization Hardness values for the recycled and upcycled materials were measured on the cross-section using a Vickers microhardness tester at 200 g load, with a dwell time of 12 s. Tensile tests were carried out on an MTS mechanical testing machine using a constant rate of 0.08 mm/min along with digital image correlation analysis measuring deformation strain. Declarations Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgments Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated by Battelle for the DOE under Contract DEAC05-76RL01830. Current work was supported by the Laboratory Directed Research and Development (LDRD) program at PNNL as part of the Solid Phase Processing Science Initiative (SPPSI). The authors are grateful for the efforts of Anthony Guzman for the preparation of specimens for microstructural characterization. This work was performed, in part, at the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. Department of Energy, Biological and Environmental Research program located at PNNL. Funding This work was supported by the Laboratory Directed Research and Development program at PNNL as part of the SPPSI. References Totten, G.E. and D.S. MacKenzie, Handbook of aluminum: vol. 1: physical metallurgy and processes . Vol. 1. 2003: CRC press. Ungureanu, C., S. Das, and I. 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Raabe, The maximum separation cluster analysis algorithm for atom-probe tomography: Parameter determination and accuracy. Microscopy and Microanalysis, 2014. 20 (6): p. 1662-1671. Additional Declarations There is NO Competing Interest. Supplementary Files Supplementary.docx SUPPLEMENTARY data Cite Share Download PDF Status: Published Journal Publication published 10 Dec, 2024 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4011560","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Letter","associatedPublications":[],"authors":[{"id":278988384,"identity":"11b340da-1d41-404d-a655-663c8ef42475","order_by":0,"name":"Xiao Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYDACZhBRICEHJBkPkKDFQMIYRBGpBQwMGBIbiNZicJz54QMGA4v07dK9Bw4w/LIB68ULJJvZjA2ADsvdOedcwgHGvjTCWviZGcwkQFo23MgxOMDYc9iYoMPYmNm/gbSkGxCthZ+ZB2xLAlgLw4/DcgS1SDbzFBskGEgY7pwB1JLYkEZYi8H54xsffKiokzeXyDF88OGPDQ9BLWCQANILYiS2EacBah2Y/EOKllEwCkbBKBgpAAD/hjaDKAw5vgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-2096-298X","institution":"Pacific Northwest National Lab","correspondingAuthor":true,"prefix":"","firstName":"Xiao","middleName":"","lastName":"Li","suffix":""},{"id":278988385,"identity":"91bf02fc-e56b-43e9-85a4-4ba52e3c6f16","order_by":1,"name":"Tianhao Wang","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Tianhao","middleName":"","lastName":"Wang","suffix":""},{"id":278988386,"identity":"4467b0ae-5087-439e-bb9e-00e56253616a","order_by":2,"name":"Zehao Li","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Zehao","middleName":"","lastName":"Li","suffix":""},{"id":278988387,"identity":"adad392a-dc4b-4f53-9d52-ffa3519dd122","order_by":3,"name":"Tingkun Liu","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Tingkun","middleName":"","lastName":"Liu","suffix":""},{"id":278988388,"identity":"5e186f42-1a32-42ec-a959-d6dbfaa1c407","order_by":4,"name":"Xiang Wang","email":"","orcid":"https://orcid.org/0000-0002-9629-3084","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Xiang","middleName":"","lastName":"Wang","suffix":""},{"id":278988389,"identity":"1fe3f560-74b9-4602-89b1-8b5b7feb770c","order_by":5,"name":"Arun Devaraj","email":"","orcid":"https://orcid.org/0000-0003-1314-6212","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Arun","middleName":"","lastName":"Devaraj","suffix":""},{"id":278988390,"identity":"8db6a9fb-ff64-47e7-ade8-fff6fbb12df6","order_by":6,"name":"Cindy Powell","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Cindy","middleName":"","lastName":"Powell","suffix":""},{"id":278988391,"identity":"217dc57b-e08e-4fdf-b92a-2d80b5f4abca","order_by":7,"name":"Jorge F. dos Santos","email":"","orcid":"","institution":"Pacific Northwest National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Jorge","middleName":"F. dos","lastName":"Santos","suffix":""}],"badges":[],"createdAt":"2024-03-04 11:17:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4011560/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4011560/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-024-53062-2","type":"published","date":"2024-12-10T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":53365922,"identity":"167e01fb-b2a2-484f-ba6b-58461d67c25a","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":229220,"visible":true,"origin":"","legend":"\u003cp\u003eAluminum life cycle and the upcycle workflow.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. Traditional secondary Al recycling and manufacturing route: sorting, melting and casting, transportation, rolling/extrusion, and semi-finished products (rod, bar, and sheet). \u003cstrong\u003eb\u003c/strong\u003e. Solid-phase processing directly recycles or upcycles scrap into extrudate via friction extrusion and reduces energy consumption by avoiding energy-intensive steps.\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/e6ae40a1ec4d54f567489660.jpeg"},{"id":53365923,"identity":"2cec9056-732c-494c-838f-43f55dca541c","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":419935,"visible":true,"origin":"","legend":"\u003cp\u003eFriction-extruded rods and their respective mechanical properties\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. Al scrap and alloying additions used in friction extrusion recycling and upcycling, from top to bottom: 6063 Al scrap, copper powder, zinc powder, and ZK60 magnesium alloy ribbons. \u003cstrong\u003eb\u003c/strong\u003e. Recycled Al rod made only from cold compacted 6063 Al scrap. \u003cstrong\u003ec\u003c/strong\u003e. Upcycled Al rod made from a mixture of 6063 Al scrap with alloying additions. \u003cstrong\u003ed\u003c/strong\u003e. EBSD-IPF showing the grain morphology of a recycled Al rod. \u003cstrong\u003ee\u003c/strong\u003e. EBSD-IPF showing the grain morphology of the upcycled Al rod. \u003cstrong\u003ef\u003c/strong\u003e. Stress-strain curves of friction-extruded samples: recycled Al rod and upcycled Al rod, compared with a commercial wrought 6063 Al alloy.\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/baf5d640d0ce5c0862c44cd9.jpeg"},{"id":53365927,"identity":"aa965000-75f5-4429-a317-7732279cefbc","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":399985,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructural evolution during solid-phase alloying\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. Optical image displaying four distinct regions from bottom to top—Zone A: compacted scrap, powders, and ribbons; Zone B: deformed materials transition from compacted microstructure to processed microstructure; Zone C: mixed and alloyed microstructure; Zone D: extruded microstructure. Note the hardness map inset in \u003cstrong\u003eFig. 3a\u003c/strong\u003e, covering the span from Zone A to Zone D. \u003cstrong\u003eb\u003c/strong\u003e. SEM and EDS mapping of Al, Zn, Mg, and Cu (from top to bottom) at Zone A, Zone B, and Zone D (from left to right).\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/ae40626f920d3a9be1b6b1fa.jpeg"},{"id":53365926,"identity":"6a295e70-b340-4c00-a12d-357e7c53fe78","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":668825,"visible":true,"origin":"","legend":"\u003cp\u003ePhase identification and microstructure of the recycled and upcycled Al via solid-phase process\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e. XRD analysis on the recycled and upcycled Al indicated that new Mg(CuZn)\u003csub\u003e2\u003c/sub\u003e phases were formed in the upcycling process. \u003cstrong\u003eb\u003c/strong\u003e. HAADF and BF images on the upcycled specimen reveal the existence of GP zone and η' phase nanoclusters. \u003cstrong\u003ec\u003c/strong\u003e. Transmission electron microscopy and EDS analysis on pre-existed Mg\u003csub\u003e2\u003c/sub\u003eSi particles reacting with newly dissolved Zn and Cu. They show potential reaction products next to pre-existing Mg\u003csub\u003e2\u003c/sub\u003eSi particles. \u003cstrong\u003ed\u003c/strong\u003e. 3D atom maps of Al, Zn, Mg, and Cu in the upcycled specimen. \u003cstrong\u003ee\u003c/strong\u003e. The desorption map of the entire atom probe tomography dataset with indexed crystallographic poles. \u003cstrong\u003ef \u003c/strong\u003eand\u003cstrong\u003e g\u003c/strong\u003e. Sliced atom maps of Al, Zn, Mg, and Cu along the [111\u003csup\u003e-\u003c/sup\u003e] pole of a selected volume with dimensions of 30 × 30 × 30 nm\u003csup\u003e3\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/3505b3c31166d6d683e6b5ae.jpeg"},{"id":53365925,"identity":"8b45aa8d-ca2a-410c-ac8e-0bda5514819c","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":569181,"visible":true,"origin":"","legend":"\u003cp\u003eExperiment procedures for both recycling and upcycling from weight measurement of chips and powders to compaction and friction extrusion.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/119c9c77e3440a85fa5a34a5.png"},{"id":71106929,"identity":"dab4877b-c97a-4664-b962-82b5276134ee","added_by":"auto","created_at":"2024-12-11 08:06:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2694577,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/742df6c0-1b3f-4ccd-8040-379d1cdc5950.pdf"},{"id":53365924,"identity":"e7ee5bf5-ddae-4a6b-a395-bfbdbfa932d4","added_by":"auto","created_at":"2024-03-25 06:28:19","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2555138,"visible":true,"origin":"","legend":"\u003cp\u003eSUPPLEMENTARY data\u003c/p\u003e","description":"","filename":"Supplementary.docx","url":"https://assets-eu.researchsquare.com/files/rs-4011560/v1/3d9edc6223b6aaa405f19782.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Upcycled High-Strength Aluminum Alloys from Scrap through Solid-Phase Alloying","fulltext":[{"header":"Main","content":"\u003cp\u003eAluminum (Al) stands as the most extensively utilized non-ferrous metal globally [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e], and the Al industry contributes 3% of all greenhouse gas emissions [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e]. This is because the Hall\u0026ndash;H\u0026eacute;roult process used to produce primary Al from ore emits a significant amount of CO\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e]. Using 100% scrap aluminum feedstocks could theoretically reduce energy and carbon emissions by up to 95% compared to primary aluminum production [\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e]. Nevertheless, this level of reduced environmental impact has not been achieved because scrap inevitably contains undesirable impurities, requiring the addition of primary Al in a process known as \u0026ldquo;purifying and diluting\u0026rdquo; [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e]. Also, the traditional production of secondary Al through recycling involves a number of energy-intensive steps \u003cstrong\u003e(\u003c/strong\u003eFig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea). The reliance on primary Al additions, combined with the requirement for high-temperature melting and other processing steps, results in a recycled product that still has a relatively high energy and carbon intensity [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e]. In this letter, we report friction extrusion as a solid-phase alloying method to both recycle and upcycle Al scrap to directly produce high-performance Al wrought extrudate in a single step, with a much lower carbon footprint (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eb). For upcycling, 6063 Al scrap and alloying sources\u0026mdash;copper (Cu) powder, zinc (Zn) powder, and ZK60 magnesium (Mg) ribbon\u0026mdash;are first physically blended and then subjected to friction extrusion, removing the requirement for bulk melting to incorporate the alloying elements into the Al matrix. The thermo-mechanical nature of the friction extrusion process results in the production of a fine-grained aluminum microstructure with a high-density of strengthening nanoclusters in the extruded product. Because this solid-phase process allows aluminum scrap to be upcycled into high-performance aluminum products without the need for either the addition of primary aluminum or melting, it has the potential to significantly reduce CO\u003csub\u003e2\u003c/sub\u003e emissions [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eAs previously described, the precursor materials used in this work (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea) include 6063 Al scrap, with alloying additions of Cu, Zn, and ZK60 Mg. The products of the upcycling process are benchmarked against a recycled 6063 alloy manufactured using the same friction extrusion approach. For the recycled alloy, cold compacted 6063 scrap was friction extruded to produce a void free, 5 mm diameter rod (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb). For the upcycled product, the mixture of 6063 scrap and alloying additions were friction extruded under similar process conditions to produce a void-free rod (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec) with a composition close to that of a standard 7075 Al alloy. The recycled rod has an average grain size of 43.1 \u0026micro;m, as shown in the electron backscatter diffraction-inverse pole figure (EBSD-IPF) map in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed. The upcycled rod, on the other hand, shows pronounced grain refinement, with an average grain size of 7.7 \u0026micro;m (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee). A comparison of the tensile stress-strain curves for the recycled 6063 Al alloy, the upcycled 6063 Al alloy, and a conventional wrought 6063 Al alloy (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ef), highlights the pronounced increase in yield strength and ultimate tensile strength for the upcycled material. Specifically, upcycling results in a\u0026thinsp;\u0026gt;\u0026thinsp;200% increase in both the yield strength (from 87 MPa to 263 MPa) and the ultimate tensile strength (from 147 MPa to 443 MPa), when compared to the recycled alloy.\u003c/p\u003e\n\u003cp\u003eExamining the microstructural evolution during the upcycling process provides insight into the origins of the differences in mechanical properties between recycled and upcycled materials. Optical microscopy of the longitudinal cross-section of the extruded rod and remnant disc (scrap/powders mixture) from the upcycling process (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea\u003cstrong\u003e)\u003c/strong\u003e reveals four distinct processing zones: an unprocessed region consisting of the compacted scrap/alloying additions (Zone A); a transition region (Zone B); a processed region (Zone C); and the extruded rod (Zone D). Process temperatures increase exponentially from Zone A to Zone C, where the highest processing temperature is reached, The colling process begins Zone D. In the present study no forced cooling was applied. Higher magnification scanning electron microscopy (SEM) images, combined with energy dispersive spectroscopy (EDS) maps, from Zones A\u0026ndash;D are also included in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb. These images show that in Zone A, the 6063 Al scrap is surrounded by Zn powders, ZK60 Mg alloy ribbons, and Cu powders, which are tightly compacted. In Zone B, the alloying additions undergo severe shear deformation and are highly strained, elongated, and fractured. In Zone C, further refining promotes dispersion and diffusion of the alloying additions into the Al matrix, prior to extrusion. In Zone D the extruded product has similar microstructural features to those observed in Zone C. It is clear from these images that the additional alloying elements Zn, Mg, and Cu become progressively more homogeneously distributed in the microstructure as the material is processed from Zone A to B, to C, and finally to D. In other words, these alloying elements are refined and mixed into the Al matrix during the friction extrusion process that took less than a minute to complete, while the Al scrap was simultaneously consolidated into the extrudate [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. These observations are supported by a hardness map (inset in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea\u003cstrong\u003e)\u003c/strong\u003e, which shows the variation in hardness that results from the above described changes in microstructure. This type of microstructure evolution during friction extrusion has been reported in our previous work on the 7075 Al alloy system [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e], and can be attributed to gradients in strain and temperature fields as the material is processed [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eTo confirm homogneity of the microstructure and chemistry of the upcycled and recycled rods, additional microscopy was conducted on both transvere and longitudinal cross-sections, with illustrative results provided in \u003cstrong\u003eFig. \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/strong\u003e (Supplementary Material Section 1). Hardness testing on the cross-sections of both recycled and upcycled rods reveals an average hardness of 43 HV for the recycled rod versus an average hardness 116 HV for the upcycled rod (\u003cstrong\u003eFig. S2\u003c/strong\u003e, Supplementary Materials Section 2).\u003c/p\u003e\n\u003cp\u003eFurther microstructural characterization of the recycled and upcycled specimens pinpoints the reason for the substantial strengthening achieved as a result of the upcycling process. X-ray diffraction (XRD) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea) indicates that Mg\u003csub\u003e2\u003c/sub\u003eSi is the dominant precipitate phase in the recycled material. In the upcycled material, \u0026eta;'/Mg(CuZn)\u003csub\u003e2\u003c/sub\u003e is present in addition to Mg\u003csub\u003e2\u003c/sub\u003eSi. High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) reveals the presence of numerous Guinier-Preston (GP) zones along with several ordered precipitates within the Al matrix (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb). A high-magnification bright field (BF) image, also shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb, confirms that the structure of the ordered precipitates is consistent with that of the \u0026eta;' phase[\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e]. Interestingly, we also found evidence that reaction occurs between pre-existing Mg\u003csub\u003e2\u003c/sub\u003eSi particles and dissolved alloying elements Cu and Zn. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec, new phases (rich in Cu and Zn) form next to Mg\u003csub\u003e2\u003c/sub\u003eSi particles. High-resolution transmission electron microscopy reveals that the newly formed phases are amorphous Mg(ZnCu), with crystalline \u0026eta;' phase/Mg(CuZn)\u003csub\u003e2\u003c/sub\u003e within the amorphous phase. More detailed information is provided in \u003cstrong\u003eFig. S3\u003c/strong\u003e (Supplementary Material Section 3) Three-dimensional atom maps of Al, Zn, Mg, and Cu distributions in the upcycled sample (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ed) reveal fluctuations in the Zn and Mg atom distributions within the Al matrix. The frequency distribution of the second nearest neighbor (2NN) distance (\u003cstrong\u003eFig. S4a\u003c/strong\u003e) reveals the presence of clusters consisting of Zn, Mg, and Cu atoms. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ee shows various crystallographic poles observed from the desorption map of the Atom Probe Tomography (APT) dataset. The stacking of (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{11}\\stackrel{\\text{-}}{\\text{1}}\\)\u003c/span\u003e\u003c/span\u003e) atomic planes are clearly resolved in the Al map along the [111] crystallographic pole (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ef). The Mg, Zn, and Cu map (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eg) shows spherical (green arrow) and elongated (red arrow) precipiates on the (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\text{11}\\stackrel{\\text{-}}{\\text{1}}\\)\u003c/span\u003e\u003c/span\u003e) planes, which correspond to Guinier-Preston I (GPI) and GPII zones [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e], respectively. The number density of the GP zones is calculated to be ~\u0026thinsp;1.6 \u0026times; 10\u003csup\u003e24\u003c/sup\u003e m\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e (\u003cstrong\u003eFig. S4b\u003c/strong\u003e). These results provide strong evidence that solid-phase alloying is achieved during the upcycling process.\u003c/p\u003e\n\u003cp\u003eTypically, the development of GP zones within an Al matrix relies on two key factors: first, the matrix must be in a supersaturated solid solution state, usually achieved through a combination of solution heat treatment and rapid quenching. Second, there should be a low-temperature artificial aging [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e] or room-temperature natural aging [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e], during which GP zones nucleate and grow. However, subjecting the material to plastic deformation after attaining a supersaturated solid solution state can significantly expedite the aging process. This acceleration is attributed to dislocations generated during plastic deformation serving as nucleation sites for GP zone formation [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. Recent research has demonstrated that continuous plastic deformation can facilitate the direct formation of GP zones without the need for further aging steps. For instance, cyclic deformation of a supersaturated aluminum alloy at room temperature results in the dynamic precipitation of solute clusters (GP zones) by continuously introducing vacancies into the matrix [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Similar observations have been made in supersaturated magnesium alloys, where equal channel angular extrusion generates excess vacancies, leading to solute segregation and direct GP zone formation [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. In the current study, the precursor materials are not in a supersaturated condition. Consequently, we hypothesize that two processes occur essentially simultaneously during the upcycling process: (1) dissolution of alloying additions into the matrix to create a supersaturated solid solution, and (2) formation of GP zones due to the continuous generation of vacancies through severe plastic deformation.\u003c/p\u003e\n\u003cp\u003eThe disparity in strength between recycled and upcycled materials (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ef\u003cstrong\u003e)\u003c/strong\u003e arises from the observed microstructural variations which can activate various strengthening mechanisms, such as grain boundary strengthening, solid solution strengthening, dislocation strengthening, and precipitate strengthening. Differences in grain size contribute to the strength increase, specifically with \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{gb}\\)\u003c/span\u003e\u003c/span\u003e (grain boundary strengthening) values of 43.2 MPa for upcycled materials and 13.1 MPa for recycled materials (refer to Supplementary Material Section 4 for detailed calculations). Alloying content variations also play a significant role in the strength difference, leveraging both solid solution strengthening and precipitate strengthening mechanisms. In particular, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{ss}\\)\u003c/span\u003e\u003c/span\u003e (solid solution strengthening) values for upcycled and recycled materials are 46.8 MPa and 7.4 MPa, respectively (detailed calculations in Supplementary Material Section 5). The assessment of precipitate strengthening relies on the 3D atom probe analysis findings depicted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ed. Notably, the presence of \u0026eta;\u0026rsquo; precipitates is considered insignificant for strength calculations. However, the presence of GP zones has a significant effect. The 3D atom probe analysis provides details on the average size and volume fraction of GP zones in the upcycled specimen, with strength contributions (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{Orowan}\\)\u003c/span\u003e\u003c/span\u003e) from GP zones amounting to 115.9 MPa. Note that the strength attributed to GP zones (coherent to the Al matrix) is anticipated to result from a dislocation shearing mechanism (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{CS}\\)\u003c/span\u003e\u003c/span\u003e) rather than an Orowan dislocation bypassing mechanism (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{Orowan}\\)\u003c/span\u003e\u003c/span\u003e). However, the calculation revealing \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{Orowan}\\)\u003c/span\u003e\u003c/span\u003e to be smaller than \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{CS}\\)\u003c/span\u003e\u003c/span\u003e implies that Orowan dislocation bypassing is the operative mechanism for GP zones in this case. A comprehensive description of the calculation is provided in Section 6 of the Supplementary Material. It is crucial to note that the recycled specimen lacks GP zones, making the determined \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{Orowan}\\)\u003c/span\u003e\u003c/span\u003e from GP zones in the upcycled specimen an indicative measure for the precipitate strength contrast between the recycled and upcycled specimens. The variation in dislocation density does not significantly influence the strength difference, with (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\sigma }_{d}\\)\u003c/span\u003e\u003c/span\u003e) (dislocation strengthening) values of 52.3 MPa for upcycled and 56.7 MPa for recycled specimens (refer to Supplementary Material Section 7 for detailed calculations). In total, theoretical calculations predict a yield strength improvement of 181 MPa in the upcycled aluminum, versus the recycled aluminum, in good agreement with the measured difference of 176 MPa.\u003c/p\u003e\n\u003cp\u003eIn summary, a high-performance Al alloy is obtained by upcycling 6063 scrap with copper, zinc, and magnesium in a single-step, solid-phase alloying process. The yield and ultimate tensile strength of the upcycled material is increased by \u0026gt;\u0026thinsp;200% compared to the recycled material, due primarily to the formation of GP zones. These results demonstrate that low-strength and low-cost Al alloy scrap can be upcycled to high-strength and high-value Al alloy products by incorporating alloying elements via scalable solid-phase processing (friction extrusion), without the need to melt the precursor materials. Severe shear deformation imposed during friction extrusion refines the alloy additions and facilitates their uniform dispersion in the Al matrix, leading to the formation of fine GP zones and \u0026eta;'/Mg(CuZn)\u003csub\u003e2\u003c/sub\u003e. Of larger significance, these results provide a first demonstration of a novel approach to alloy design and manufacturing that creates value from waste, reduces the energy footprint and environmental impact of metals production, and offers a pathway to entirely new alloys and composites that cannot be produced by conventional melt-based proesses.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eBase materials and tooling\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003e6063 Al alloy scrap, Zn powders, Cu powders, and ZK60 Mg alloy ribbons were used as feedstock materials in this study. The chemical compositions of the 6063 Al alloy and ZK60 Mg alloy are provided in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. A ZK60 Mg alloy was selected instead of pure Mg to avoid flammability issues. The chemical composition of the target 7075 Al alloy is also listed in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eFriction extrusion tooling was made of H-13 tool steel. Spiral grooves were machined into the die face to facilitate material flow into the extrusion orifice, with a diameter of 5 mm. Die temperature was measured during processing using a type-K thermocouple (TC) spot-welded approximately 0.5 mm back from the die face.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eNominal chemical composition of 6063 scrap, additional alloying powders and ribbons, mixed precursor, and standard 7075 [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003eMaterial\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"7\" align=\"left\"\u003e\n\u003cp\u003eChemical composition (wt. %)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eAl\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eMg\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSi\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eZn\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eCu\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eFe\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eZr\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6063 scraps\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBal.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.45\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.02\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.02\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eCu powders\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eZn powders\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eZK60 ribbons\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBal.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u0026ndash;5.5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.57\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMixed precursor\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBal.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5.6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.01\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eStandard 7075 Al\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBal.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2.1\u0026ndash;2.5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u0026ndash;0.5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5.6\u0026ndash;6.1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1.2\u0026ndash;1.6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u0026ndash;0.5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003e\u0026bull; Friction extrusion process\u003c/h2\u003e\n\u003cp\u003eThe manufacturing process for the recycled and upcycled rods is illustrated in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. First, precursor scrap and alloying elements were weighed out according to the chemical compositions shown in \u003cstrong\u003eTable. 1\u003c/strong\u003e. Based on the amount of 6063 scrap and the additional additives, the final weight percentages of Mg, Cu, and Zn in the upcycled material were approximately 2.5%, 1.6%, and 5.6%, respectively. Second, the precursor materials were loaded into a plastic bottle, and the bottle was sealed and placed on a roller mixer for 1 hour. Third, the premixed precursor was loaded into a billet container and cold compacted with ~\u0026thinsp;110 MPa using a hand press. Then, the liner with the pre-compacted precursor was loaded for friction extrusion into a ShAPE\u0026trade; machine manufactured by Bond Technologies. Critical friction extrusion parameters, such as starting and steady-state spindle speed and plunge speed are listed in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eCritical friction extrusion parameters for recycling and upcycle processes.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eProcess\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eStarting material\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eSpindle speed (RPM)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003ePlunge speed (mm/min)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eRecycle\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6063 Al alloy scrap\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFrom 300 to 100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFrom 6 to 4 and 2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eUpcycle\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6063 Al alloy scraps\u0026thinsp;+\u0026thinsp;Zn powders\u0026thinsp;+\u0026thinsp;Cu powders\u0026thinsp;+\u0026thinsp;ZK60 Mg alloy ribbons\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFrom 300 to 100\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eFrom 6 to 4 and 2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003e\u0026bull; Sample preparation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eFriction extrusion specimens were cut along the transverse cross-section and longitudinal cross-section using a diamond blade. Specimens for microstructural analysis were mounted in epoxy and polished to a final surface finish of 0.05 \u0026micro;m using colloidal silica.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eThree mini-tensile specimens were machined from the 5 mm diameter extruded rods for both the recycled and upcycled materials. The round bar specimens had a 38.1 mm total length and 15.88 mm gage length, following the ASTM-E8 standard.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003e\u0026bull; Microstructural characterization\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eOptical microscopy was performed using an Olympus BX-51 fluorescence motorized microscope.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eScanning electron microscopy (SEM) was performed using a Thermo Fisher Scientific Quanta 200 focused ion beam (FIB)-SEM outfitted with an Oxford Instruments X-ray energy dispersive spectroscopy (EDS) system for compositional analysis. Electron backscatter diffraction (EBSD) was done using a Thermo Fisher Scientific Apreo 2S SEM with an Oxford Instruments EBSD detector operating at 20 kV and step size of 0.2 \u0026micro;m. The EBSD results were analyzed using ZtecCrystal EBSD processing software.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eTransmission electron microscopy (TEM) specimens were prepared by following the routine lift-out and thinning procedure of the FIB technique on a Thermo Fisher Scientific Quanta 200 FIB-SEM or a Thermo Fisher Scientific Helios 5 Hydra Dual Beam plasma focused ion beam milling scanning electron microscopy (PFIB-SEM).\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eTEM/scanning TEM (STEM) observations were performed on an FEI (now Thermo Fisher Scientific) Titan 80\u0026ndash;300 Environmental Cs-corrected TEM equipped with an EDS system. High-angle annular dark field (HAADF) and bright field (BF)-scanning transmission electron microscopy (STEM) images were captured on a JEOL GrandARM-300F operating at 300 kV with a convergence semi-angle of 29.7 mrad. The collection angles for HAADF-STEM were between 75 and 515 mrad.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eX-ray diffraction analysis was performed using a Rigaku D/Max Rapid II microdiffraction system. Diffraction data recorded on a two-dimensional image plate were integrated for diffraction angles between 20\u0026deg; and 150\u0026deg; using the manufacturer's software (2D Data Processing Software v.1.0, Rigaku, 2007).\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003e3D atom probe (3DAP) analysis was performed using a local electrode atom probe (CAMECA LEAP 6000 XR) in voltage pulse mode with a pulse fraction of 20% at a temperature of 40 K. Sharp needle-like specimens for the 3DAP analysis were prepared by the FIB lift-out and annular milling techniques using an FEI Helios 5 Hydra UX. The statistics and chemistry of precipitates in the selected volume without the Al poles were analyzed using a maximum separation algorithm in the AP Suite\u003csup\u003e\u0026trade;\u003c/sup\u003e 6.3 software. The parameters of separation distances (\u003cem\u003ed\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e = 0.58), minimum number of solutes (\u003cem\u003eN\u003c/em\u003e\u003csub\u003emin\u003c/sub\u003e = 12), envelop distances (\u003cem\u003eL\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.58), and erosion distances (\u003cem\u003ed\u003c/em\u003e\u003csub\u003eerosion\u003c/sub\u003e = \u003cem\u003eL)\u003c/em\u003e were selected based on the nearest neighbor approach described elsewhere [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003e\u0026bull; Mechanical property characterization\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eHardness values for the recycled and upcycled materials were measured on the cross-section using a Vickers microhardness tester at 200 g load, with a dwell time of 12 s.\u003c/p\u003e\n\u003c/li\u003e\n\u003cli\u003e\n\u003cp\u003eTensile tests were carried out on an MTS mechanical testing machine using a constant rate of 0.08 mm/min along with digital image correlation analysis measuring deformation strain.\u003c/p\u003e\n\u003c/li\u003e\n\u003c/ul\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated by Battelle for the DOE under Contract DEAC05-76RL01830. Current work was supported by the Laboratory Directed Research and Development (LDRD) program at PNNL as part of the Solid Phase Processing Science Initiative (SPPSI). The authors are grateful for the efforts of Anthony Guzman for the preparation of specimens for microstructural characterization. This work was performed, in part, at the William R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. Department of Energy, Biological and Environmental Research program located at PNNL.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Laboratory Directed Research and Development program at PNNL as part of the SPPSI.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTotten, G.E. and D.S. MacKenzie, \u003cem\u003eHandbook of aluminum: vol. 1: physical metallurgy and processes\u003c/em\u003e. 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Choi, and D. Raabe, \u003cem\u003eThe maximum separation cluster analysis algorithm for atom-probe tomography: Parameter determination and accuracy.\u003c/em\u003e Microscopy and Microanalysis, 2014. \u003cstrong\u003e20\u003c/strong\u003e(6): p. 1662-1671.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4011560/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4011560/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAlthough 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 novel 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 high density of Guinier-Preston zones and uniformly precipitated nanoscale η'/Mg(CuZn)\u003csub\u003e2\u003c/sub\u003e strengthening phases, enhances both yield and ultimate tensile strength by \u0026gt;\u0026thinsp;200%. By delivering high-performance products from scrap that are not just recycled but \u003cem\u003eupcycled\u003c/em\u003e, this scalable manufacturing approach offers a new paradigm of metals reuse, with the option for on-demand upcycling of a variety of metallic materials from scrap sources.\u003c/p\u003e","manuscriptTitle":"Upcycled High-Strength Aluminum Alloys from Scrap through Solid-Phase Alloying","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-25 06:28:14","doi":"10.21203/rs.3.rs-4011560/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e91ab90e-2ff9-4199-86c7-9a2b52b9d76b","owner":[],"postedDate":"March 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":29381459,"name":"Physical sciences/Materials science/Structural materials/Metals and alloys"},{"id":29381460,"name":"Physical sciences/Engineering/Mechanical engineering"}],"tags":[],"updatedAt":"2024-12-11T08:06:12+00:00","versionOfRecord":{"articleIdentity":"rs-4011560","link":"https://doi.org/10.1038/s41467-024-53062-2","journal":{"identity":"nature-communications","isVorOnly":false,"title":"Nature Communications"},"publishedOn":"2024-12-10 05:00:00","publishedOnDateReadable":"December 10th, 2024"},"versionCreatedAt":"2024-03-25 06:28:14","video":"","vorDoi":"10.1038/s41467-024-53062-2","vorDoiUrl":"https://doi.org/10.1038/s41467-024-53062-2","workflowStages":[]},"version":"v1","identity":"rs-4011560","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4011560","identity":"rs-4011560","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}