Search Results (214)

At present, the detection methods for the microstructure and mechanical properties of aluminum alloys are mainly based on SEM, EBSD, TEM, tensile tests, and microhardness tests, which are time-consuming and destructive. In this paper, laser ultrasonic non-destructive detection is employed to obtain ultrasonic signals from Al-Cu-Mg aluminum alloy subjected to various heat treatment processes. The results reveal empirical correlations between the characteristic values of the ultrasonic signals and the material’s state. Specifically, the characteristic values exhibit an inverse correlation with the precipitated phase content. When both the precipitated phase content and the average grain size vary significantly, distinct deviations in the characteristic values are observed, which can serve as indicators of microstructural changes. The extracted ultrasonic eigenvalues also show promising, empirically derived correlations with mechanical properties, with frequency-domain attenuation coefficients demonstrating relatively higher sensitivity based on fitting analyses within the current dataset. These observed variations are tentatively discussed as plausible consequences of grain boundary scattering and changes in matrix solid solution strengthening associated with precipitate dissolution. Overall, the findings suggest the potential of laser ultrasonics as a rapid non-destructive evaluation tool, providing a preliminary scientific basis for further development of methods to assess the microstructure and mechanical properties of Al-Cu-Mg alloys within the tested parameter space. Full article

The present study examines the influence of plastic deformation on the corrosion behavior of aluminum alloy EN AW-2024 (AlCu₄Mg) in an acidic medium (0.5 M H₂SO₄). Specimens without deformation and with a degree of plastic deformation of 25%, 33% and 50% were studied. Corrosion tests were carried out using the gravimetric method for a period of 72 h. The inhibitory effect of environmental inhibitors—ascorbic acid (vitamin C) and citric acid—was also evaluated. The results show that the degree of plastic deformation has a significant influence on the corrosion rate of the studied alloy. The lowest corrosion rate is observed at 25% deformation, while at higher degrees, the resistance decreases. It was found that citric acid exhibits the highest inhibitory effect at 33% deformation (77.27%), while vitamin C shows a better effect at 50% deformation. The results obtained show that the optimal degree of deformation in combination with a suitable inhibitor can significantly improve the corrosion resistance of EN AW-2024 alloy in acidic environments. Full article

In this work, a non-standardized hypereutectic aluminum–silicon alloy AlSi21Cu5MgCr intended for the automotive industry is presented. The modification of the alloy is performed with the conventional modifier phosphorus in an amount of 0.04 wt%. The applied metallurgical treatment is the basis for the obtained modified structure. It has been established that after conducting the T6 heat treatment, the free silicon crystals are reduced to 26.9 µm, and the eutectic silicon crystals are spherical in shape and have dimensions not exceeding 8 µm. The macrohardness of the studied alloy is 168.5HV_10/10, a value significantly higher than that required for this type of alloy, which is in the range of 95 ÷ 137 HV (90 ÷ 130 HB). The microhardness of the α-phase in the composition of the eutectic is 154 µHV_50/10, which indicates that after quenching a saturated solid solution was fixed, and during the artificial aging process secondary strengthening phases were formed and separated. A CrAlN hard coating was deposited on the alloy surface. The mechanical properties of the coating were characterized by a hardness of 14 GPa, whereas the AlSi21Cu5MgCr substrate had a hardness of 2 GPa. The results showed considerable improvement of the hardness of the new alloy and well-tuned elastic–plastic properties. The obtained adhesive properties are compatible with this class of materials. The composition of the CrAlN hard coating is homogeneously distributed on the alloy surface and the morphology is improved. The investigations showed that CrAlN hard coatings could successfully be applied for the modification of the surface of AlSIMgCu alloys. Full article

Understanding the complex relationships between processing conditions and mechanical properties in aluminum alloys remains a critical challenge in materials science. This study presents a data-driven framework using explainable artificial intelligence to quantify and interpret how different processing routes influence the strength–ductility trade-off in aluminum alloys. Using a comprehensive dataset of 1154 aluminum alloy samples with 10 distinct processing conditions, optimized XGBoost models were developed via Bayesian hyperparameter tuning to predict yield strength (R² = 0.9392), tensile strength (R² = 0.9491), and elongation (R² = 0.6767). The strength models showed high predictive accuracy, whereas elongation showed lower and less uniform reliability, with the largest relative errors in the 0–5% elongation regime. SHAP (SHapley Additive exPlanations) analysis revealed that processing condition is the most influential feature for yield strength prediction, while Cu dominates tensile strength prediction. True SHAP interaction analysis identified Processing_encoded interactions with Cu as the strongest processing-coupled contribution, followed by Mg and Al, with Zn, Si, and Li showing smaller but non-negligible interaction contributions. The decision-tree surrogate is presented as an exploratory rule-extraction tool rather than as a standalone processing-selection classifier. These findings demonstrate that explainable Machine Learning (ML) can support interpretation of processing–property relationships in aluminum alloys when predictive limitations, class imbalance, and the associative nature of SHAP explanations are explicitly considered. Full article

This study investigated how initial ingot thickness (400 mm vs. 520 mm) influences the microstructure and mechanical properties of Al–Zn–Mg–Cu alloys rolled to 80 mm. The combination of smaller initial thickness and lower total reduction (the 400-L route) results in lower dislocation density and a higher fraction of metastable η′ precipitates after T77 treatment. In contrast, the 520-L route, which involves a larger initial ingot thickness coupled with greater rolling reduction, yields higher dislocation density and a greater proportion of stable η phase. Texture also differs: the 400 mm ingot develops a strong S texture and high anisotropy, whereas the 520 mm ingot exhibits Brass texture and reduced anisotropy. Specifically, cross-rolling plus longitudinal rolling of the 520 mm ingot enhances recrystallization texture, giving a short-transverse yield strength of 528 MPa—within 6% of the longitudinal direction. This work offers valuable insights for controlling anisotropy in large 7xxx aluminum plates. Full article

Rapid solidification by melt-spinning produces aluminum alloys with extremely refined microstructures but also introduces strong structural gradients across the ribbon thickness. In this work, the microstructural evolution of a rapidly solidified Al-Cu-Li-Mg-Sc-Zr alloy was investigated during model homogenization using in situ STEM heating experiments and correlated with bulk electrical-resistivity measurements. The as-cast ribbons exhibit two distinct solidification zones: a near-contact region consisting of columnar cells containing fine Cu-rich spherical precipitates, and a central region composed of larger eutectic cells enriched in Al₂Cu and Al₇Cu₂Fe phases. Stepwise in situ STEM annealing between 200 °C and 500 °C reveals a sequence of transformations, including matrix depletion due to precipitation of strengthening phases, coarsening of primary phases, and formation of Al₃(Sc,Zr) dispersoids. Above 500 °C, rapid dissolution of Cu-rich primary phases occurs, leaving only a limited number of stable grain-boundary particles of the Al₇Cu₂Fe phase, eliminating the original two-zone structure, and resulting in a fully homogenized ribbon. Ex situ annealing confirms that the resulting microstructure is uniform across the ribbon thickness and enables consistent precipitation strengthening during artificial aging. The proposed annealing treatment is based on numerical models for homogenization of eutectic systems. The final annealing step combines homogenization and solution treatment at 530 °C for periods close to 5 min—two orders of magnitude shorter than standard holding times. Microhardness measurements from both ribbon surfaces reveal an identical peak-aged hardness of 135 HV, validating the effectiveness of the short-time homogenization strategy for rapidly solidified Al-Cu-Li-Mg-based alloys. Full article

Aluminum alloys, particularly those in the Al-Cu and Al-Mg-Si series, are extensively employed in aerospace, automotive, and structural applications owing to their favorable strength-to-weight ratio. However, optimizing their mechanical and surface properties to meet advanced performance requirements remains a critical challenge. Over the past three decades, extensive research has explored thermochemical treatments, precipitation hardening, and thermomechanical processing, yet most studies have examined these methods in isolation. This review systematically analyzes the influence of each treatment route on microstructural evolution, precipitation behavior, and mechanical performance, with emphasis on grain refinement, precipitation kinetics, surface hardening, and fatigue resistance. Particular attention is given to severe plastic deformation, advanced surface modification techniques, and aging behavior under different conditions. The review also highlights gaps in the current literature, including limited integration of hybrid treatment cycles, insufficient understanding of coupled diffusion-precipitation mechanisms, a lack of high-temperature performance data, and minimal industrial-scale validation. Future research directions are proposed to develop optimized hybrid processing strategies, predictive computational models, and scalable treatment cycles. This consolidated review provides a comprehensive foundation for advancing aluminum alloy design, aiming to achieve tailored surface-to-core property gradients suitable for next-generation aerospace and automotive applications. Full article

A comparative investigation of the corrosion behavior evolution of 15%SiCp/Al-Cu-Mg aluminum matrix composites (AMC) subjected to different heat treatments in a salt spray environment containing 5wt% NaCl was performed. Metallographic microscopy was used to observe the surface morphology of the corroded materials. Field-emission transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for microstructural evaluation and elemental analysis of the samples. Polarization curves and electrochemical impedance spectroscopy (EIS) were also employed to investigate the corrosion performance of the particle-reinforced aluminum matrix composites under different heat treatments. The test results indicate that, in addition to the influence of various grain boundary precipitates and electrochemical inhomogeneities between the precipitate-free zone (PFZ) and the aluminum matrix, differences in electrochemical properties between the SiC reinforcement particles and the aluminum alloy matrix are also a primary factor contributing to the corrosion of the aluminum-based composites in a 5wt% NaCl salt spray environment. Microstructural observations and electrochemical testing of AMC specimens at different corrosion stages indicate that under-aged samples exhibit relatively higher intergranular corrosion susceptibility. Under prolonged exposure to a salt spray environment, the over-aged specimen exhibited more pronounced galvanic corrosion phenomena, specifically, a significant decrease in Charge transfer resistance (R_ct) values and an increase in CPE values. R_ct results indicate that naturally aged AMC exhibits higher corrosion resistance than artificially aged AMC. With increased salt spray corrosion time, varying degrees of crevice corrosion occurred at the Al–SiC interface in all heat-treated samples. Full article

In nuclear power, marine engineering, and other fields, a matching system composed of duplex steel and copper alloy is a common combination for rotating components in a seawater environment. However, this system is susceptible to galvanic corrosion that seriously threatens its service safety and service life, with ZCuAl10Fe5Ni5 being the main component corroded. Additionally, current corrosion research on this system has evident gaps. Specifically, the influence of area ratio on galvanic corrosion remains insufficiently understood, and the action mechanism of Cl⁻ on the ZCuAl10Fe5Ni5-based corrosion product film in seawater, as well as the product evolution path, has not been fully revealed, which restricts the development of targeted protection technologies. This study explores the degradation mechanism of ZCuAl10Fe5Ni5 in a specific high-salinity environment (20,000 mg/L Cl⁻), characteristic of nuclear power plant service conditions. The results show that due to the significant electrode potential difference between the SAF2507 duplex steel and ZCuAl10Fe5Ni5 copper alloy, a stable galvanic couple is formed, with ZCuAl10Fe5Ni5 acting as the anode and undergoing dissolution corrosion. When the area ratio of ZCuAl10Fe5Ni5 (anode) to SAF2507 duplex steel (cathode) is 1:50, a significantly stronger galvanic effect is observed. The high concentration of Cl⁻ in seawater can damage the surface of the ZCuAl10Fe5Ni5-based corrosion product film, leading to intensified local corrosion. The ZCuAl10Fe5Ni5-derived corrosion products have a layered structure mainly comprising a mixed system of Cu-Al-Mg oxides/hydroxides, and the corrosion process is accompanied by selective aluminum depletion corrosion. This study provides insight into the corrosion mechanism and key influencing factors of ZCuAl10Fe5Ni5 in the matching system, as well as a theoretical basis and technical support for the design of compatibility metal materials in a seawater environment and the control of corrosion in ZCuAl10Fe5Ni5. Full article

Cr-based composite coatings with superior wear resistance are in growing demand for high-performance applications in the automotive, aerospace, and general manufacturing sectors. In this study, an Al10Cu alloy produced via powder metallurgy was coated with a chromium/nanodiamond (Cr/ND) composite layer using an electrodeposition process to enhance its tribological performance. The coatings were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The resulting Cr/ND layer exhibited a uniform thickness of 73.5–76.2 μm and markedly improved surface hardness (809.4 HV), representing a 15-fold increase over the uncoated alloy (53.6 HV). Pin-on-disk tribological testing under dry sliding conditions showed complete elimination of detectable mass loss (0.00 mg vs. 0.55 mg for uncoated) within the measurement system resolution, indicating excellent resistance to both abrasive and adhesive wear. XRD analysis revealed the formation of a hexagonal close-packed Cr₂H phase with incorporated nanodiamond particles. To capture and predict the temporal evolution of the friction coefficient, a customized dual-layer long short-term memory neural network—optimized with a look-back window of 3 timesteps and ReLU-activated dense layers—was implemented. The model achieved superior predictive performance on the coated system, with validation and test R² values of 0.9973 and 0.9965, respectively, demonstrating enhanced modeling accuracy for surface-engineered materials. These findings demonstrate a significant advancement in wear protection for aluminum alloys and introduce a robust data-driven approach for real-time friction prediction in engineered surfaces. Full article

Al/TiB₂ aluminum alloy laminates were fabricated using a combination of accumulative roll bonding (ARB) and cold rolling processes. The Al/TiB₂ interface and microstructure were meticulously characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties of the laminates were assessed through tensile testing. The experimental results demonstrate that with an increasing cold rolling reduction, a laminated composite sheet with a nanocrystalline structure was successfully produced. The critical strain for the onset of plastic instability was also investigated. The findings indicate that as the cold rolling reduction increases, severe necking occurs in the Al12Zn2.2Mg1.7Cu3TiB₂ layer. At a reduction of 80%, the necking region approaches fracture. Tensile results reveal that this pronounced necking has a detrimental effect on the strength of the laminate. It is proposed that the plastic instability originates from shear bands, and the mechanical property mismatch between the constituent layers is identified as the primary reason for the localized preferential deformation. Full article

The 6xxx series aluminum alloys are preferred in many industrial applications because they can achieve relatively high strength levels through heat treatment. It is known that, as in the case of the EN AW 6056 alloy, the addition of small amounts of copper to materials in this series can further enhance their mechanical properties. In the current study, the effect of artificial aging conditions on the mechanical properties of EN AW 6056 aluminum alloy has been investigated. The ratio of Mg to Si and Cu content of the alloy were 0.939 and 0.92, respectively. The aging process was conducted at temperatures of 170, 180, and 190 °C, with corresponding aging durations of 1, 2, 3, 4, 6, 8, 12, 15, 18, 21, and 24 h. The maximum hardness was obtained in samples aged at 170 °C for 12 h, corresponding to the transition to over-aging condition. In contrast, the highest tensile strength was achieved in samples aged at 190 °C for 4 h, representing the peak-aged condition. Transmission electron microscopy (TEM) analyses revealed distinct microstructural characteristics for the peak-aged and transition to over-aging conditions. In the peak-aged state, needle-shaped β″ precipitates, lath-like Q′ phases, and L phases with narrow rectangular cross-sections were observed. In contrast, lath-like L precipitates were absent in the transition to over-aging condition. Full article

7xxx series aluminum alloys are critical structural materials in aerospace applications, but their susceptibility to hydrogen embrittlement (HE) poses significant challenges to service safety and durability. The effects of Si, Er, and Zr microalloying, combined with optimized heat treatments on the HE resistance of Al–Zn–Mg–Cu alloys, were systematically investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and mechanical testing. Three alloys—1# (AlZnMgCuZr), 2# (AlZnMgCuErZr), and 3# (AlZnMgCuSiErZr)—were subjected to single-stage or two-stage homogenization, followed by solution treatments at 470 °C/2 h and 540 °C/1 h, and peak aging at 125 °C. The hydrogen charging experiment was conducted by first applying a modified acrylic resin coating to protect the gripping sections of the specimen, followed by a tensile test. Results demonstrate that alloy 3# with Si addition exhibited the lowest RA_loss, followed by the 2# alloy, which effectively improved the alloys’ hydrogen embrittlement behavior. Compared with the solution in 470 °C/2 h, the 540 °C/1 h solution treatment enabled complete dissolution of Mg₂Si phases, promoting homogeneous precipitation and peak hardness comparable to alloy 2#. Two-stage homogenization significantly enhanced the number density and refinement of L₁₂-structured Al₃(Er,Zr) nanoprecipitates. Silicon further accelerated the precipitation kinetics, leading to more Al₃(Er,Zr) nanoprecipitates, finely dispersed T′/η′ phases, and lath-shaped GPB-II zones. The GPB-II zones effectively trapped hydrogen, thereby improving HE resistance. This work provides a viable strategy for enhancing the reliability of high-strength aluminum alloys in hydrogen-containing environments. Full article

Carbon nanotubes/2Al2 composites, due to their low density, high specific strength, and high elastic modulus, are representative lightweight structural materials for next-generation aerospace applications. Traditional processing methods are inefficient and have long production cycles, making them unsuitable for the demands of efficient, rapid, and intelligent manufacturing of complex structures. This article proposes the use of metal additive manufacturing technology to solve this problem. For the first time, a 22 mm high carbon nanotube/2Al2 composite was fabricated using additive friction stir deposition, and the changes in surface morphology, microstructure, mechanical properties, and corrosion resistance of the as-deposited composite were systematically studied. After additive manufacturing, the composite exhibited a continuous and defect-free, typical onion-like structure. The as-deposited microstructure consists of uniformly equiaxed grains with an average grain size of 1.23 μm to 1.62 μm and uniformly distributed Al₂Cu particles. The tensile strength and elongation of the as-deposited composite in both the transverse and processing directions are no less than 450 MPa and 15%, respectively, superior to those of the base material. After additive manufacturing, the as-deposited composite exhibited a corrosion current density of 0.19 μA cm⁻² in the transverse direction—only 4% of that of the base material. This enhanced corrosion resistance is attributed to the uniform distribution of precipitated phases achieved through additive manufacturing, which suppresses micro-galvanic corrosion, resulting in minimal, uniform corrosion. This study provides a research foundation and technical support for the additive manufacturing of aluminum-based composites. Full article

The typical microstructure and mechanical properties of twin-roll cast (TRC) 2139 aluminum alloy were investigated and compared with mold casting (MC) 2139 alloy. This work pioneers the application of TRC to produce 2139 Al-Cu-Mg alloy, a material that is challenging for rapid solidification. The TRC process resulted in a denser dendritic structure, with the composition of intermetallic compounds, primarily Al₂Cu and Al₂CuMg, remaining largely stable throughout the casting process. After solution treatment, the recrystallized grains in the MC sheets were uniformly distributed, while the TRC sheets exhibited a more localized and refined recrystallized microstructure, particularly within coarse second-phase regions. Following heat treatments, the TRC sheets showed a significant increase in the Ω phase after T6, with a slight growth in size and a uniform distribution, while the Ω phase in T8 showed an increased density and smaller size, which diffused evenly across the material. The TRC process uniquely refines the microstructure and enhances Ω phase precipitation, yielding a 10%+ improvement in strength and ductility over conventional casting. The mechanical properties of the TRC sheets improved significantly: tensile and yield strengths increased by over 10% after T6, compared to MC sheets, with elongation slightly higher in TRC. T8 treatment further enhanced the mechanical properties of the TRC sheets, achieving an improvement in strength with only a minor trade-off in elongation. This establishes TRC as a superior industrial route for high-performance aluminum sheets, offering a promising industrial route, delivering substantial improvements in both strength and ductility over conventional casting methods. Full article