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Oct 14, 2024

Nanotechnology enabled casting of aluminum alloy 7075 turbines | npj Advanced Manufacturing

npj Advanced Manufacturing volume 1, Article number: 6 (2024) Cite this article 441 Accesses Metrics details Aluminum alloy 7075 is well-known for its high-performance structural systems due to its

npj Advanced Manufacturing volume 1, Article number: 6 (2024) Cite this article

441 Accesses

Metrics details

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

In light of technological advancements in industries, such as the aerospace and automotive sectors, the demand for strong, lightweight, and intricate components and systems has surged, driven by the pursuit of enhanced performance and energy efficiency. Among the materials pivotal to meeting these demands is aluminum alloy 7075 (AA7075), esteemed for its lightweight nature and one of the best strength-to-weight ratios offered by commercial alloys. However, despite its advantageous attributes, manufacturing AA7075 parts typically involves mechanical working processes1. These processes are resource-intensive and inefficient for producing complex components, often necessitating subsequent joining through welding or riveting, which can compromise structural integrity2. While casting is well-known for creating intricate, one-piece parts, there are significant challenges in casting AA7075. This alloy has a high susceptibility to hot cracking3 and limited fluidity4, which impede the casting of net-shaped products. These problems underscore the need for innovative solutions to develop novel manufacturing processes for complex AA7075 components while ensuring cost-effectiveness and structural integrity.

Previous research has elucidated the underlying causes of the hot cracking and limited fluidity observed in AA7075. During the solidification process, the significant solidification shrinkage characteristic of aluminum alloys5,6 induces void formation and thermal stress within the semisolid network. Moreover, the high alloy content of AA7075 leads to a wide freezing range, facilitating unrestricted dendrite growth. Consequently, this coarse dendritic network constrains the ability of the liquid phase to adequately fill the voids generated by shrinkage, ultimately leading to cracks5,7,8. Furthermore, investigations into aluminum alloy fluidity, both theoretical9,10 and empirical11,12 demonstrate that alloys with wider freezing ranges exhibit reduced fluidity lengths, which can be attributed to the solidification mechanism.

Although there is a comprehensive understanding of the mechanisms behind hot cracking and fluidity, achieving casting in complex AA7075 parts remains a significant challenge. Various approaches, including process design and metallurgical adjustments13, have been explored to enhance the castability and performance of this alloy. Incorporating reinforcement particulates through methods such as stir and squeeze casting has shown promise in improving strength, wear resistance, and corrosion resistance14,15,16. However, these methods are not capable of producing complex structures, particularly those with thin walls17. Die casting emerges as a promising solution for thin-wall casting18, but it faces severe challenges with AA7075 19,20,21 due to the high cooling rate of the process. No previous results have succeeded in die-casting thin-wall structures with this alloy, and investigations into fluidity are lacking. A study by Shin et al4. stands out for simultaneously addressing hot cracking and fluidity by modifying the composition of AA7075. However, potential changes in mechanical performance have not been fully explored, and no complex parts have been cast to validate these findings. Another manufacturing technique for precision casting of complex thin wall structures is investment casting, known for its superior surface quality and precision22. However, its application to AA7075 has not yet been successful due to the intrinsic low cooling rate, resulting in coarse phases23, in addition to severe hot cracks and shrinkages.

Nano-treating, by incorporating a low amount (e.g., less than 1.0 vol%) of nanoparticles into the metal matrix, has emerged as a promising technique for enhancing both the manufacturability and performance across various alloy systems24,25,26,27. This nanotechnology-enhanced manufacturing method has demonstrated success in welding28,29 and fusion-based additive manufacturing30,31,32 processes for complex AA7075 structures, tasks traditionally challenging to address solely through metallurgical or process optimization means. Recent investigations into aluminum alloy casting have further highlighted its potential to enhance the fluidity of Al-Cu-Mg and Al-Mg-Si systems33,34. Nevertheless, the impact of nano-treating on the castability of AA7075, notorious for its limited fluidity and susceptibility to hot cracking during casting, remains largely unexplored. Furthermore, there is a lack of evidence from the actual casting process substantiating the effects of nanoparticles on the castability of aluminum alloys. To address this gap, this study starts with investigating the effect of nano-treating on the castability of AA7075. Specifically, it first evaluates how TiC nanoparticles impact fluidity, hot cracking, surface roughness, and microstructure. Subsequently, turbines featuring intricate thin-wall structures, which present significant casting challenges, were fabricated using both pure and nano-treated AA7075 via investment casting.

Figure 1a illustrates the fluidity results for AA7075 alloy with 0, 0.5, and 1 vol% of TiC nanoparticles, referenced respectively as AA7075, AA7075-0.5TiC, and AA7075-1TiC. The results demonstrate an increase in vacuum pressure correlates with an extension in fluidity length. However, it is observed that the enhancement in fluidity length is more pronounced in the nano-treated alloys compared to the pure AA7075, indicating superior fluidity behavior. Specifically, AA7075-1TiC exhibits a significant increase in fluidity length as the vacuum pressure rises, while AA7075-0.5TiC displays the highest fluidity performance among the tested alloys across all pressure levels.

Fluidity length plotted against a pressure and b TiC nanoparticle content, derived from vacuum fluidity test. c Representative crack samples of AA7075 under 45 kPa vacuum pressure.

The introduction of TiC nanoparticles has a positive effect on the fluidity behavior, resulting in enhanced flow distance compared to that of pure AA7075 samples. Figure 1b illustrates the correlation between nanoparticle vol% and fluidity length under varying levels of vacuum pressure (15, 30, and 45 kPa). Notably, 0.5 vol% of TiC nanoparticle addition exhibits the highest fluidity length under all three pressure conditions among all alloys tested. Under 15 kPa pressure, AA7075-1TiC exhibited a lower fluidity length closer to pure AA7075, but as the pressure increased to 45 kPa, its fluidity length approached that of AA7075-0.5TiC. Samples without nanoparticles showed the lowest fluidity lengths. The addition of TiC nanoparticles resulted in a significant increase in fluidity length by over 20% at 15 kPa and around 40% at 30 and 45 kPa, highlighting the effectiveness of nanoparticle incorporation in enhancing fluidity characteristics of the alloy.

Furthermore, the presence of nanoparticles significantly mitigated hot cracking. Figure 1c depicts that all four fluidity test specimens of pure AA7075 under 45 kPa vacuum pressure exhibited hot cracking due to rapid cooling at higher pressure. However, through incorporating nanoparticles, the number of cracks notably decreased. While 8 out of 12 pure AA7075 samples cracked, only one sample with 0.5 vol% TiC nanoparticle addition experienced cracking under 45 kPa pressure, and none of the samples with 1 vol% TiC showed any cracking.

Analysis of displacement in slow-motion vacuum fluidity test videos (Fig. 2) provides insights into the improved fluidity of nano-treated aluminum alloy samples. Notably, nano-treated samples exhibited prolonged flow durations compared to pure AA7075. In the figure, the flow of nano-treated alloys persisted for 0.04 s longer (about a 17% increase) than pure AA7075. Regarding flow speed, the AA7075-0.5TiC alloy exhibited a relatively higher flow speed than the other two alloys, resulting in the greatest fluidity length. The AA7075-1TiC alloy exhibited the slowest average flow speed under 15 kPa pressure among the three alloys, resulting in a comparatively shorter fluidity length. However, as pressure increased to 45 kPa, the flow speed approached that of AA7075-0.5TiC, leading to a higher fluidity length.

Time–displacement curves obtained from vacuum fluidity test.

Illustrated in Fig. 3a–c are the microstructures of the three alloys, highlighting the efficacy of nano-treating in refining the grain structure of AA7075. Without nanoparticles, AA7075 exhibited large and dendritic grain structures. However, compared to pure AA7075, AA7075-0.5TiC showed smaller grains with reduced dendritic characteristics, while AA7075-1TiC displayed even finer, more granular grains. Figure 3d illustrates the results of grain size analysis. The addition of TiC nanoparticles at 0.5 and 1 vol% led to a significant reduction in grain size, by 63% and 75%, respectively. Similar results can be observed in Fig. 4, which depicts the scanning electron microscope (SEM) images of the flow tip. The grain morphology at the flow tips of the nano-treated samples demonstrates a finer and less dendritic crystal structure than pure AA7075. Figure 4d offers a closer view of the AA7075-1TiC tip, revealing a significant distribution of TiC nanoparticles both on and between the grains. The Ti signals depicted in Fig. 4e further confirm this distribution. The concentration of nanoparticles here exceeded the designed 1 vol%. Previous studies have shown that 1 vol% TiC nanoparticles are generally well-dispersed within the AA7075 matrix under standard casting conditions35,36. Therefore, the high concentration observed at the flow tip may be an unusual result specific to the fluidity test experiment.

a AA7075, b AA7075-0.5TiC, and c AA7075-1TiC; d Grain size analysis results for the three alloys.

The flow tip morphology of a AA7075, b AA7075-0.5TiC, and c AA7075-1TiC. d Shows a magnified view of TiC nanoparticle distribution at the flow tip of AA7075-1TiC, while e displays the corresponding energy dispersive spectroscopy (EDS) mapping.

The left section of Fig. 5 illustrates the surfaces of fluidity test samples for the three alloys. The pure AA7075 sample contains significant voids, whereas samples with higher vol% of nanoparticles demonstrate smoother and glossier surfaces. No evident voids are observed in the AA7075-1TiC sample. In the 3D profiles depicted on the right side of Fig. 5, the pure AA7075 sample displays larger peaks (shown in red) and valleys (in blue) compared to the AA7075-1TiC sample, where predominantly green colors indicate smoother surfaces. The roughness average (RA) for the three alloys is measured at 20.94, 15.28, and 8.50 µm, respectively. This indicates a reduction in roughness of 27% and 59% with the addition of 0.5 and 1 vol% TiC nanoparticles, respectively.

a AA7075, b AA7075-0.5TiC, and c AA7075-1TiC samples.

The turbine featured in Fig. 6a was chosen for rapid investment casting due to its intricate thin-wall design, which posed a challenge for traditional casting methods. This turbine, with 0.5 mm thick fins, served as an ideal candidate to demonstrate the enhanced fluidity achieved through nano-treating. The as-printed condition of the turbine structure for mold building is shown in Fig. 6b. Subsequently, the turbine was cast using pure AA7075 and AA7075-1TiC for comparative analysis, with the outcomes displayed in Fig. 6c, d, respectively. A 1 vol% concentration of TiC nanoparticles was selected to effectively eliminate hot cracking while maintaining fluidity comparable to that of a 0.5 vol% TiC addition under high pressure. In Fig. 6c, incomplete structures on the fins and central cylinder, resulting from inadequate filling, are evident in the pure AA7075 turbine, indicating its poor fluidity characteristics. Moreover, cracks were observed in the areas marked by red arrows. Conversely, the turbine cast with AA7075-1TiC displayed a complete structure closely resembling the original model, highlighting a notable improvement in fluidity and resistance to hot cracking due to nano-treating.

a Computer model; b As-printed condition; casting results of c AA7075 and d AA7075-1TiC.

Figure 7a, b displays the 3D reverse scanning models of the two turbines, used for comparing against the original computer model to evaluate filling percentages. In Fig. 7c, d, the blue areas indicate overlapping regions between the casting results and the original model. The analysis reveals that pure AA7075 failed to fill much of the fin structure and the top of the central cylinder. In contrast, nano-treated AA7075 exhibited predominantly blue areas, with only a few unfilled corners. Remarkably, the nano-treated casting achieved an impressive filling percentage of 96.44%, while the pure AA7075 managed only 64.06% of the turbine structure.

a AA7075 and b AA7075-1TiC turbines; The overlapping area, depicted in blue, between the original turbine model and the scanning results of c AA7075 and d AA7075-1TiC turbines.

Figure 8 illustrates the microhardness of AA7075 and AA7075-1TiC turbines in both as-cast and T6 conditions, as well as wrought AA7075 in T6. The addition of TiC nanoparticles significantly enhanced hardness compared to the pure AA7075 turbine, showing a 15% increase in the as-cast condition and a 12% increase after T6 heat treatment. Compared to the hardness of wrought AA7075, the cast samples exhibit greater variability, which may be attributed to defects introduced during the casting process. However, with nano-treatment, the hardness of the AA7075 cast turbine after T6 heat treatment approaches that of wrought AA7075-T6, indicating the significant strengthening effect of nanoparticles.

Microhardness measurements for AA7075 and AA7075-1TiC turbines in as-cast and T6 conditions, as well as for wrought AA7075 in T6.

The extended fluidity length, elimination of hot cracking, and enhanced surface quality observed in nano-treated samples can be attributed to the proven effects of nanoparticles: reduced grain size, delayed solidification, and enhanced molten alloy wettability26,34,35.

Due to the wide freezing range of AA7075, dendrite arms can grow freely through the long solidification process, forming a complex semisolid network. This network impedes the flow of the remaining liquid phase, making it difficult to fill the vacancies left by solidification shrinkage and thermal contraction. Thermal stress concentrates on this weak structure, leading to hot cracking. However, TiC nanoparticles can be effectively dispersed in molten Al due to their great wettability and suitable intermolecular forces35,37. When well-dispersed in the AA7075 alloy melt, these TiC nanoparticles act as nucleation sites, promoting rapid nucleation. Moreover, nanoparticles hinder the solidification front and restrain grain growth, resulting in a fine and granular grain structure, as depicted in Fig. 3. This fine and granular system enables easier flow of the liquid phase, facilitating the filling of voids during the final stage of solidification, and effectively eliminating hot cracking35.

Additionally, most TiC nanoparticles were pushed by the solidification front of the α-Al during the solidification process and densely packed around the small grains. Due to their lower thermal conductivity and the blocking of the diffusion path of constituents into the grain, the release of latent heat from aluminum is hindered, resulting in a slower solidification process35. Consequently, a higher liquid fraction in the melt is observed in the nano-treated sample. Sokoluk et al.35 demonstrated this through computer-aided thermal analysis (CATA). The temperature history of pure AA7075 and AA7075-1TiC during the controlled casting process was recorded and analyzed to determine the percentage of solid fraction in the melt during solidification (Fig. 9). The results indicate that the nano-treated AA7075 melt maintained a higher liquid fraction throughout the entire solidification process. At 500 °C, the terminal stage of solidification in Fig. 9b, the TiC nano-treated melt exhibits approximately 2% higher liquid fraction compared to the pure AA7075 melt. Therefore, the increased liquid fraction and the finer grains present in the final stage of solidification effectively prevent hot cracking issues in nano-treated alloys.

a Comparison of solid fraction versus temperature curves for the pure and nano-treated AA7075 melts, along with enlarged segments depicting b late-stage and c early-stage solidification processes35.

The extended fluidity length observed in the nano-treated samples can also be explained by these nanoparticle effects. The established fluidity flow stoppage mechanism9 indicates that rapid cooling leads to the formation of α-Al crystals near the flow tip, which eventually coalesce into a dendrite network, impeding flow (Fig. 10a). However, this mechanism is enhanced with the addition of nanoparticles. Firstly, nanoparticles restrict grain growth, resulting in the formation of finer, more granular grains at the flow tip, as depicted in Fig. 10b. Unlike the dendritic structure observed in alloys without nanoparticles, this system offers reduced shear resistance to the liquid flow behind it, leading to a longer fluidity length. SEM images of the flow tip (Fig. 4) further support the enhancement of the flow stoppage mechanism.

a Pure alloys and b TiC nanotreated alloys, illustrated by α-Al represented in black and TiC nanoparticles in green.

Secondly, nanoparticles delay latent heat release and slow down solidification. It has been found that a 30% solid fraction at the flow tip could cause flow cessation9. According to the CATA results from Sokoluk et al.35 in Fig. 9c, the temperature required for pure and nano-treated AA7075 melts to reach a solid fraction of 30% is about 628 °C and 623 °C, respectively. Consequently, as evidenced by the time-displacement curves in Fig. 2, the flow incorporating nanoparticles persists for an extended duration under equivalent vacuum pressure, resulting in increased fluidity length.

Previous research on the fluidity of nano-treated AA2024 and AA606333,34 has demonstrated that nanoparticles enhance the wettability between the molten material and the glass tube. This improved wettability not only enhances surface quality but also leads to a higher initial flow rate during vacuum fluidity tests, ultimately improving overall fluidity. Similar observations were made in this study on AA7075. Under 45 kPa, the nano-treated samples not only exhibit a higher initial flow speed, as illustrated in the time-displacement curves (Fig. 2), but also show a noticeably smoother surface (Fig. 5). The improved wettability of the molten material also facilitates the complete filling of the turbine fin corners, as illustrated in Fig. 6d.

A common approach to refining the grain size of aluminum alloys is the addition of grain refinement agents such as the Al–Ti–B modifier. However, excessive use of such modifiers may alter alloy composition, thus affecting fluidity behavior. Consequently, the relationship between grain refinement and fluidity remains debated, primarily due to the absence of a definitive quantitative correlation38,39. Previous research has shown that TiC nanoparticles are relatively stable in the molten AA7075 and do not change its composition26,30,36. Furthermore, merely incorporating grain refinement can rarely reach the finely granular grain structure and improved solidification behaviors achieved through nano-treating. Therefore, nano-treating presents a potentially more effective approach for enhancing fluidity, while also addressing hot cracking and improving surface quality.

Despite the advantages of nano-treating, such as slower solidification, grain refinement, and improved wettability, the addition of 1 vol% TiC does not exhibit a higher fluidity length compared to 0.5 vol% TiC at lower pressures. This could be attributed to nanoparticles being pushed by the solidification front and carried along to the flow front during the metal flow. Particularly during the long solidification process of AA7075, nanoparticles could densely accumulate around the flow tip, as evidenced by SEM images in Fig. 4d. Studies on nanofluids indicate that nano-sized particles in a liquid flow can significantly increase viscosity40. Incorporating nanoparticles into molten metal has been found to increase viscosity severalfold41,42. Hence, in the case of nano-treated AA7075 melt, the time-displacement curve indicates that under 15 kPa, the sample with 1 vol% TiC exhibits the slowest flow speed among the three alloys. However, increasing the pressure appears to mitigate the issue, as the fluidity length of the AA7075-1TiC increases most significantly with pressure. Therefore, the addition of 1 vol% TiC nanoparticle can be considered for high-pressure applications, as it most effectively addresses the issue of hot cracking and achieves the best surface quality.

Based on the vacuum fluidity test results, a concentration of 1 vol% TiC nanoparticles was selected for the AA7075 turbine investment casting experiment. The casting results (Fig. 6) revealed significant differences between the turbine cast with and without nanoparticles. In the absence of nanoparticles, the turbine exhibited incomplete shaping, with unsuccessful formation of fin structures and notable defects such as misrun and cracking. Conversely, the nano-treated AA7075 showcased exceptional fluidity, effectively filling the entire mold, including the thin fin structures. This casting outcome aligns with the findings of the vacuum fluidity test, highlighting that nano-treating enhances the castability of AA7075. It further demonstrates the capability of nano-treating to enable the casting of traditionally difficult-to-cast alloys in challenging thin-wall casting processes. Moreover, the improved hardness of the AA7075-1TiC turbine supports the previously observed strengthening effect of nanoparticles26,31,32, indicating that both strengthening and castability enhancement can be achieved simultaneously.

The following procedure was applied to produce AA7075 (Al–5.9Zn–2.8Mg–1.6Cu–0.25Cr) with 0, 0.5, and 1 vol% of TiC nanoparticles. Initially, high-purity aluminum (purity > 99%, from American Elements Inc.) was melted in a graphite crucible using an induction furnace at 820 °C under Ar gas protection. Temperature control was maintained using two k-type thermocouples to keep temperatures within a ±3 °C range. The temperature was held at 820 °C throughout the entire process to prevent any undesired reactions between the aluminum and the TiC nanoparticles43. Subsequently, an Al–3.5 vol% TiC master nanocomposite fabricated using a molten salt-assisted in-situ synthesis method44 (from MetaLi LLC) was gradually introduced to achieve the desired vol% of TiC nanoparticles. Additional amounts of pure Zn, Mg, Cu, and Cr (purity > 99.99%, from American Elements Inc.) were then added. The melt was manually stirred for 5 min using a graphite bar to ensure the uniform dispersion of the nanoparticles. The alloying content was confirmed using PerkinElmer NexION 2000 inductively coupled plasma optical emission spectrometry (ICP-OES), with the results listed in Table 1.

Fluidity testing was conducted via a vacuum setup45 (Fig. 11), where varying vacuum pressure levels (15, 30, and 45 kPa) were applied to draw the 820 °C molten metal into bent Pyrex glass tubes. The distance that the molten metal traveled along the horizontal tube section before solidification determined the fluidity length. Previous studies have confirmed the reproducibility of this setup, with detailed information provided34. Each condition underwent four rounds of testing, with the recording of metal flows using an iPhone 13 Mini in slow-motion mode. Recordings were then analyzed frame by frame to obtain the time vs. displacement data of the tip.

Vacuum fluidity test setup.

Test specimens were prepared by gently removing the glass tube, and then cutting, grinding, and polishing. Microstructures were revealed through etching with Weck’s reagent (100 mL H2O + 1 g NaOH + 4 g KMnO4). Grain size analysis was performed using the Heyn lineal intercept method as described in ASTM E112. For each sample, three locations were analyzed, with five intercepts per location, using ImageJ software to determine grain sizes. Solidification morphology and nanoparticle distribution at the top of the flow tips were examined using a Zeiss Supra 40VP SEM equipped with energy dispersive spectroscopy (EDS). Surface topology analysis of the sample side surfaces utilized a Veeco Wyco NT9300 white light interferometer. Surface quality was quantified using average roughness, calculated as the arithmetic mean of absolute profile heights over the evaluation length.

The turbine investment casting process depicted in Fig. 12 involved several steps. Initially, a turbine pattern measuring 60 mm in diameter and 30 mm in height, with 0.5 mm-thick fin structures, was printed using the ELEGOO Saturn 2 masked stereolithographic apparatus (MSLA) printer. After printing, the part was cleaned and cured under UV light before being assembled onto a wax tree. Next, a slurry was prepared by mixing investment powder (from Prestige Optima) with water at a mass ratio of 100:40. This slurry was poured into a flask with a diameter of 7.62 cm and a height of 8.89 cm, enclosing the pattern. After solidification, the investment mold was heated to 780 °C for 5 h to remove the wax tree and polymer prints. Finally, the ceramic shell was preheated to 450 °C before casting.

Turbine rapid investment casting schematic.

For the casting process, 100 g of AA7075 with 1 vol% of TiC nanoparticles was prepared using the described method and poured into the preheated mold within the VEVOR HH-CM01 investment casting machine. The machine applied a vacuum pressure of 60 kPa to the mold during casting. After cooling to room temperature, the ceramic shell was carefully removed, revealing the tree structure, and the turbine was detached. To compare the effectiveness of the TiC nano-treatment, an identical turbine was cast using pure AA7075 alloy under the same conditions. Both turbines, with and without nanoparticles, were then scanned using the Artec Space Spider 3D scanner. The resulting 3D models were compared with the original turbine model using CloudCompare software to estimate the filling percentage.

Vickers microhardness measurements were conducted using a LECO LM-800AT tester, with ten measurements taken per sample under a load of 200 gf and a dwell time of 10 s. Samples measuring 1 cm × 1 cm were extracted from the fins of both AA7075 and AA7075-1TiC turbines, polished, and then tested to determine their hardness in the as-cast condition. To evaluate hardness in the T6 condition, the as-cast samples were solutionized at 470 °C for 1 h, followed by water quenching and artificial aging at 120 °C for 16 h. Additionally, a hot-rolled AA7075-T6 sheet from McMaster-Carr was cut and polished to measure the hardness of wrought AA7075 in the T6 condition, providing a comparison with the hardness of cast samples.

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The authors would like to thank MetaLi LLC for their generous provision of equipment and raw materials.

Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, 90095, USA

Guan-Cheng Chen, Yitian Chi & Xiaochun Li

RWTH Aachen University, Aachen, 52062, Germany

Till Felix Reufsteck

Department of Materials Science and Engineering, University of California, Los Angeles, CA, 90095, USA

Xiaochun Li

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G.C. and T.F.R. developed and performed the vacuum fluidity test. G.C. performed the material characterizations. G.C. and Y.C. developed and performed the turbine investment casting. G.C. wrote the paper with the support of T.F.R. and Y.C. X.L. designed the project, provided supervision, and revised the paper.

Correspondence to Xiaochun Li.

X.L. is the founder and chief scientist of MetaLi LLC. X.L. holds patent 20210388469—-nano-treatment of high-strength aluminum alloys for manufacturing processes.

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Chen, GC., Reufsteck, T.F., Chi, Y. et al. Nanotechnology enabled casting of aluminum alloy 7075 turbines. npj Adv. Manuf. 1, 6 (2024). https://doi.org/10.1038/s44334-024-00004-x

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Received: 15 July 2024

Accepted: 22 August 2024

Published: 01 October 2024

DOI: https://doi.org/10.1038/s44334-024-00004-x

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