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This document discusses the determination of residual stress in aluminum alloy aerospace components using the blind hole drilling method and optical interferometric measurements. The study presents experimental procedures and uncertainty analysis for measuring residual stresses in materials. The results show that the method provides accurate and reliable results with a low level of uncertainty. The document also provides a list of references related to the measurement of residual stresses, discussing various methods and their applications in different fields. [Extracted from the article]

Al alloys and aluminum matrix composites (AMCs) are characterized by high specific strength, high specific modulus, and low density. As one of the most promising advanced lightweight materials, Al alloys and AMCs are widely used in high-speed railway, aerospace, defense, and other cutting-edge fields. However, with the urgent demand for lighter and more complex structures in these high-tech fields, traditional processing methods have shown huge limitations, such as long manufacturing process, low material utilization, restricted design and structure of parts. Fortunately, the rapid development of additive manufacturing technology in recent years has greatly expanded the flexibility of design and manufacturing. As a representative technology of metal additive manufacturing, laser powder bed fusion (LPBF) has outstanding advantages such as high accuracy, high material utilization and short production cycle. LPBF of Al alloys and AMCs is an effective method for producing complex and lightweight structural parts, however, at the meantime, it also faces huge challenges. In this article, the current research status of the LPBF processed Al alloys and AMCs are reviewed with main focus on powder preparation, LPBF technology and subsequent treatments. [ABSTRACT FROM AUTHOR]

The development of high-strength cold spray deposits using amorphous/nanocrystalline aluminum high-entropy alloy (Al HEA) powder is hindered by the lack of understanding of correlations between powder microstructure and its deformation behavior. In this study, gas-atomized Al HEA powder (Al90.05-Y4.4-Ni4.3-Co0.9-Sc0.35 at.%) is devitrified at 298, 345, 362, and 450 °C to optimize strength and deformation for cold spraying. Devitrification-induced atomic rearrangement developed equiaxed Al grains and Al3Ni and Al3Sc precipitates. The amorphous content, growth of grains, hard precipitates, and reduced dislocation density increased the hardness by 16% to 515 HV at 298 °C and decreased the hardness by 55% to 190 HV at 450 °C. The compressive strength of Al HEA powder increased by 5% to 1559 MPa at 298 °C and decreased by 49% to 760 MPa at 450 °C. To enhance the limited sprayability of Al HEA powder, compressive strength is used to model optimized cold spray process maps. Helium gas with temperatures from 300 to 800 °C and a pressure of 40 bar can produce cold spray deposits with deposition efficiency greater than 70%. The scientific insights acquired from the present study provide a gateway toward developing novel lightweight and high-strength aluminum alloy deposits, thus marking an advancement in cold spray technology. [ABSTRACT FROM AUTHOR]

The efficient hydrogen-production through the Aluminum-water reaction has become a prominent subject of interest. The impediment encountered in the reaction can be effectively alleviated by Aluminum-based alloy. In this study, density functional theory (DFT) was utilized to explore the mechanism of water decomposition stage on the surface of aluminum and gallium alloy (AGA). Through surface reaction calculations of 12 stable AGA configurations, it was gradually revealed that the optimal alloy ratio was gallium-to-aluminum at 3.5:1. Analysis of the density of states (DOS) indicated that the presence of gallium amplified the activity of surface aluminum. Moreover, frontier orbital theory and charge density maps confirmed that, due to the weak interaction between Ga and ions, the presence of H 2 inhibited Ga passivation, thereby enhancing the reactivity of AGA. This paper provided valuable insights into the surface reaction mechanisms of AGA using DFT, offering theoretical support for hydrogen production processes. • Density functional theory investigated the early stages of AGA-water reaction. • Modeling AGA (Ga proportions 73.8%–81.2%) yields 12 stable configurations. • Ga:Al = 3.5:1 exhibits highest energies for O 2 , H 2 O, and co-adsorption. • Ga enhances AGA's catalytic activity, shown in DOS graphs comparisons. • AGA plays dual roles in surface hydrogen dynamics. [ABSTRACT FROM AUTHOR]

Cylindrical foam castings of Al and A356 alloy were produced using a melt foaming method with the introduction of Ca and TiH2. Foam crystallization takes place in a cooled thin-walled metal mold. Samples cut off from the foam castings are investigated by X-ray tomography, quantitative data for porosity, average pores diameter and average cells wall thickness are obtained. It is found that the porosity is mainly open. Same samples are tested in quasi-static mode and the compressive strength is determined. The influence of porosity on compressive strength is analyzed. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) emerges a broad application and development prospects in the joining of dissimilar materials. Friction stir lap welding (FSLW) of 6061-T6 aluminium (Al) alloy sheet with different depths groove pretreatment and polycarbonate (PC) sheets is investigated. Weld surface defects are studied by visual inspection. The analyses of microstructures and mechanical tensile properties of the dissimilar joints are carried out by optical microscopy (OM) and tensile tests. Results indicate that the groove depth is a significant factor affecting the welding surface morphology. Tensile strength reaches the maximum with the average value of 29.05 MPa at the groove depth of 0.2 mm, which is equivalent to 58% of the PC base material strength. Microstructure analysis indicates that the molten PC and Al alloy fragments flow along the groove at the action of the pin tool. Simultaneously, Al alloy fragments are inserted into the molten PC material. The two materials form a compact mixed structure, which improves the tensile strength. [ABSTRACT FROM AUTHOR]

Background: Residual stress development in precipitation strengthened aluminium foundry alloys has seen little attention, despite the prevalence of their use over a wide array of applications. Objective: This study aims at the evaluation of the residual stress in a cast aluminium benchmark that develops during precipitation heat treatment and determines the preferable stress relaxing techniques for such applications. Methods: The stress states in the as-cast, T4 and T6 tempers of the same AlSi7Cu0.5Mg (A356 with 0.5 wt% Cu) sample were determined through a novel application of the contour method, standard hole drilling, deep hole drilling and incremental deep hole drilling. Results: The results of all measurement techniques lie within approximately 40 MPa for all regions available for comparison, with the greatest differences occurring between the contour method and deep hole drilling for the T6 component. It is shown that the peak tensile residual stresses are almost identical between the heat-treated components (75 MPa), but the distribution and magnitude of compressive residual stress are found to be significantly different. Conclusions: Among the measurement techniques evaluated, the contour method and incremental hole drilling are found to be more suitable for T6 temper, while all techniques perform equally well for T4 temper due to its relatively low strength. It is hypothesised that the difference between the as-cast and heat-treated samples is due to solution heat treatment and quenching, while the difference in T4 and T6 tempers is attributed to the response to ageing. [ABSTRACT FROM AUTHOR]

The effects of vacuum induction melting and various concentrations (range of 0–8% by weight) of the titanium aluminium carbide (Ti2AlC) phase on the mechanical and tribological properties of Aluminium hypereutectic alloy (A390) were investigated. The addition of Ti2AlC particles enhances the strength and wear resistance of A390 alloy and also exerts a positive effect on its ductility, Moreover aerospace and automotive brake rotors deserved high strength and high wear resistance. The quick induction heating process could decrease the thermal energy degradation of the Ti2AlC particles into an Al alloy matrix alloy. The structural, microscopic and elemental analysis carried out to observe the hard precipitate components and reveal the various phases of the composites. The addition of Ti2AlC inclusions altered the morphology of eutectic silica to be globular and improved the grain size and evenly distributed within the A390 (Al-16Si) matrix. As the content of Ti2AlC reaches 8 wt% the strength and microhardness of the composites increased 74% and elongation decreased 2.1% (UTS = 285 MPa, H = 127VMH and EI = 1.1%). The tensile and fracture behaviour of the composites has been studied at 30 °C, 150 °C, and 250 °C. The Johnson-Cook model theoretically calculated the accurate flow stress of the Al-16Si/Ti2AlC composites. The negligible decrease in strength and ductility at 250 °C was observed. The root mean squared error (RMSE) and mean absolute percentage error (MAPE) values for the stress-strain curves prove the higher relationship between the theoretical and experimental values. The composites containing 8 wt% Ti2AlC reinforcement significantly enhanced the mechanical behaviour with a porosity < 2.23%.Therefore this composite exhibited appreciable tribological properties. It appeared that the wear mechanism of the composites abrasive wear at applied pressure 0.2 MPa with sliding distance 2000 m was prevailing. The ANN model addressing the parameters which influence the wear rate and friction coefficient as well as the experimental wear analysis of these composites was correlated precisely with the results of this model. [ABSTRACT FROM AUTHOR]

This document is a compilation of various research papers and articles that discuss the use of machine learning and other techniques to predict fatigue lifetimes in different materials and structures. The papers cover topics such as the use of neural networks, XGBoost, and physics-informed machine learning models for fatigue prediction. The research focuses on different materials, including aluminum alloys and lead-free solders, and explores the effects of factors such as wear, lubrication, corrosion, and stress on fatigue life. The papers provide insights into the application of machine learning techniques in predicting fatigue lifetime and offer potential solutions for improving the accuracy of these predictions. [Extracted from the article]

Additive manufacturing (AM) is a highly advanced manufacturing technology that involves metal layers deposition in order to increase the efficiency of component production and costs reduction. Current study includes examining the effects of adding aluminium as an additional alloying element to austenitic stainless-steel SS 309L. Metal Inert Gas (MIG) welding apparatus was used as a heat source for the deposition of the steel in the Wire Arc Additive manufacturing method. Simultaneously during the building process, three different percentages (0, 2.5%, and 5%) of an external aluminium alloy 4043 (E4043) cold wire was introduced into the fusion zone. The focus of the study is to highlight the influence of adding E4043 on the microstructure and mechanical properties of additively manufactured SS309L. For the microstructural investigations, optical microscopy and scanning electron microscopy (SEM) were used, whereas a Vickers microhardness test was used to investigate the effect of these additions on the local mechanical properties. On the other hand, the mechanical behavior of the deposited parts was examined using tensile test. The results of the study demonstrated that the addition of the aluminum alloy is significantly affect the mechanical properties of the deposited portions. The quantity of the added aluminum is discovered to have an influence on the microstructure, hardness, and tensile strength. Moreover, the homogenizing thermal treatment improved the samples' microstructure and overall properties. The found results highlights the importance of considering double wire feeding in additive manufacturing processes to reach the desired microstructural and mechanical properties in the final products. [ABSTRACT FROM AUTHOR]

This paper proposes a Whipple structure to enhance the impact resistance of graphene/aluminum alloy composites by varying the interlayer spacing between graphene and aluminum alloy. The increased interlayer spacing provides more deformation space for the graphene to absorb more deformation energy, and enables the formation of a debris cloud from the bullet fragments and graphene fragments, significantly reducing the impact energy per unit area of the next material. The impact limit serves as a critical metric for assessing the impact resistance of the Whipple structure. Based on molecular dynamics simulations, we developed a machine learning model to predict the protection of aluminum alloy, and quickly determined the impact limits of velocity, bullet radius, and interlayer spacing by using the machine learning model. An empirical equation for the impact limit of interlayer spacing was established. The results showed that non-zero interlayer spacing can significantly improve the impact resistance of the hybrid structure; to fully exploit the superior impact resistance of this Whipple structure, the number of graphene layers should be at least 3. Furthermore, at high impact velocities and large bullet radii, the impact limit of the interlayer spacing exhibits a substantial correlation with the number of graphene layers. These results provide valuable information for the design of the impact resistance of the graphene/aluminum alloy composites. [ABSTRACT FROM AUTHOR]

To efficiently enhance the bonding performance of aluminum lithium alloy, the surface morphology characteristics of the samples were constructed by copper chloride rapid etching method. The microstructure, roughness characteristics, wetting performance, and bonding joint strength performance of different modified surfaces were compared and analyzed. The results show that compared to the original surface and sandpaper grinding method, rapid etching can effectively enhance the surface wettability and adhesive strength of the sample. When the etching time is 5,10, and 15s, the strength of the adhesive joint of the untreated sample is increased by 217. 6%,245. 9%, and 270. 3 %, respectively. The Increase of etching time contributes to the construction of concave convex stepped morphology and the increase of surface roughness, thereby improving the actual contact area and mechanical interlocking of the bonding interface, promoting the penetration and adhesion of the adhesive on the substrate surface, and thereby improving the strength performance of the bonding joint. [ABSTRACT FROM AUTHOR]

This work investigates temperature's effect on the critical energy release rate using damage mechanics material models and the element deletion method. The energy release rate describes the decrease in total potential energy per increase in crack surface area. The critical energy release rate is widely used as the failure criterion for various elastic and plastic materials. In real-life scenarios, fractures may occur at different temperatures. The temperature dependency of the critical energy release rate for aluminum 2024-T351 and titanium Ti-6Al-4V is studied in this work. We utilized test-data-based advanced material models of these two alloys, considering the strain rate, temperature, and state of stress for plasticity and failure. These material models are used to simulate a three-dimensional fracture specimen to find the critical energy release rate at different temperatures. A new method to calculate the critical energy release rate with the element deletion method is introduced and verified with the virtual crack opening method. This method enables the calculation of the energy release rate in a classical damage mechanics simulation for dynamic cack propagation. The simulation result indicates that the critical energy release rate increases with rising temperatures for these alloys. [ABSTRACT FROM AUTHOR]

Electromagnetic treatment (EMT) plays a critical role in the manipulation of microstructures and properties in aluminum alloys. This study aims to investigate the impact of EMT on stress corrosion cracking (SCC) resistance in 7075 aluminum alloy and to reveal the underlying mechanisms from both thermodynamic and kinetic perspectives. The results demonstrate that EMT has a significant positive effect on the stress corrosion resistance of the aluminum alloy. It effectively reduces the elongation loss from 11.2 to 2.6% and the SCC susceptibility index from 3.9 to 1.4%. This improvement can be attributed to two primary mechanisms: (1) the energy supplied by the electromagnetic field lowers the thermodynamic barriers for the dissolution of precipitates, even at temperatures below the critical threshold. This facilitates the dissolution and coarsening of precipitates, ultimately reducing the alloy's susceptibility to stress corrosion in various environments. (2) The activation energy provided by the electron wind force facilitates the movement and annihilation of dislocations, leading to a reduction in residual stresses and further enhancing the aluminum alloy's resistance to stress corrosion. [ABSTRACT FROM AUTHOR]

Melting, solidification, and viscosity properties of multicomponent Fe-Cu-Nb-Mo-Si-B alloys with low aluminum addition (up to 0.42 at.% Al) were studied using an oscillating cup viscometer. It is shown that melting and solidification are divided into two stages with a knee point at 1461 K. The temperature dependences of the liquid fraction between the liquidus and solidus temperatures during melting and solidification are calculated. It has been proven that aluminum accelerates the processes of melting and solidification and leads to an increase in liquidus and solidus temperatures. In the liquid state at temperatures above 1700 K in an alloy with a low aluminum content, the activation energy of viscous flow increases. This growth was associated with the liquid–liquid structure transition, caused by the formation of large clusters based on the metastable Fe23B6 phase. Aluminum atoms attract iron and boron atoms and contribute to the formation of clusters based on the Fe2AlB2 phase and metastable phases of a higher order. [ABSTRACT FROM AUTHOR]

Direct water spraying (DWS) is an approach similar to ablation casting using direct impingement of water spray on the solidifying casting but is modified in that it no longer relies on eroding removal of the sand bound by water-soluble binders. A removable part of the sand mold is withdrawn during the process, and water is directly sprayed on the exposed casting surface. Two commercial casting Al alloys, i.e., A413 with short to zero and A356 with a wider freezing range, were processed by the DWS method. Comparison of the conventional and DWS-processed castings with respect to the microstructure and mechanical properties was evaluated via computer-aided thermal analysis, metallography, and tensile testing. The average ultimate tensile strength (UTS) increased from 126 to 193 MPa in A356 and 139–159 MPa in A413 by applying the DWS method. The elongation was increased from 2.8 to 11% in the DWS A356 and from 1.8 to 5% in the DWS A413. The secondary dendrite arm spacing (SDAS) was decreased from 80 µm in A356 to 44 µm and from 68 µm in A413 to 32 µm in the respective DWS-processed counterparts. The experimental results confirmed that a longer freezing range is more favorable with the DWS process, producing improved castings with higher tensile properties. [ABSTRACT FROM AUTHOR]

The 6061‑aluminum alloy is most used in marine engineering equipment. We used composite co-deposition to prepare a Cu/Co-Mo-Ce alloy coating on the aluminum alloy surface, which not only solved problems related to the ready corrosion of aluminum alloy in marine environments and the difficulty of directly preparing protective coatings but also solved problems associated with the fact that CoMo alloy form many holes by introducing the rare earth Ce. An exploration of the plating process revealed that when the concentration of the other main salts was unchanged and the concentration of Ce3+ was 0.012 mol·L−1, the Cu/Co-Mo-Ce had the flattest morphology, and the best corrosion resistance. The coatings were characterized and analyzed using SEM, EDS, XRD, and XPS. Finally, the ions deposition processes were tested via cyclic voltammetry and chronoamperometry and AC impedance. [ABSTRACT FROM AUTHOR]

Diffusion coefficients in the BCC phase of the Al–Nb–V ternary system are studied for the first time, including an assessment of the atomic mobilities. Ternary interdiffusion coefficients are obtained from the intersecting diffusion paths of several sets of diffusion couples that are annealed at both 1100 °C and 1200 °C. Existing experimental data from the pertinent binary systems are also employed for the assessments of atomic mobilities using the 1-parameter Z-Z-Z binary diffusion coefficient model developed by Zhong et al [1]. Interdiffusion coefficients in the BCC region of the Al–V system are also extracted through a forward-simulation analysis and incorporated into the mobility modeling. A complete description of diffusion in the BCC phase of the Al–Nb–V system is presented following the Binary and Cross-Binary Parameters Only (BCBPO) model developed by Zhong and Zhao [2]. Our data will be valuable input to diffusion-related simulation of refractory high entropy alloys containing aluminum. [ABSTRACT FROM AUTHOR]

Radiation-based gauges have been widely utilized in the industry as a dependable, non-destructive method of measuring metal layer thickness. It is only possible to trust the conventional radiation thickness meter when the material's composition is known in advance. Thickness measurement errors are to be anticipated in contexts like rolled metal factories, where the real component of the material could diverge greatly from the stated composition. An X-ray-based device was suggested in this study to measure aluminum sheet thickness and identify the type of its alloys. Transmission and backscattered X-ray energy were recorded using two sodium iodide detectors while a 150 kV X-ray tube in the described detection system was operated. Aluminum layers of varying thicknesses (2–45 mm) and alloys (1050, 3105, 5052, and 6061) were simulated to be placed between the X-ray source and the transmission detector. The development of radiation-based systems used the MCNP code as a very powerful framework to imitate the detecting architecture and the spectra acquired by the detectors. The recorded signals were transferred to the frequency domain using the Fourier transform, and the frequency characteristics were extracted from them. Two GMDH neural networks were trained using these characteristics: one to identify the alloy type and another to determine the aluminum layer's thickness. The classifier network had a 92.2% success rate in identifying the alloy type, while the predictive network had a 1.9% error rate in determining the thickness of the aluminum layer. By extracting important characteristics and using powerful neural networks, this study was able to improve the precision with which aluminum layer thickness was measured and correctly identify the alloy type. The suggested method is used to determine the thickness of aluminum and its alloy sheets and may also be applied to other metals. • An X-ray-based device was suggested to measure aluminum sheet thickness and identify the type of its alloys. • Transmission and backscattered X-ray energy were recorded using two NaI detectors. • The recorded signals were transferred to the frequency domain using the Fourier transform. • Two trained GMDH neural networks determined the alloy type and the aluminum layer's thickness. [ABSTRACT FROM AUTHOR]

The 6016 aluminum alloy has good plasticity but low strength. In this work, Al-Ti-Sc master alloy was prepared by thermite reduction method in order to obtain an effective grain refiner with a simplified preparation process and a reduced cost. The refining effects of the ternary master alloy on the 6016 aluminum alloy were checked to improve the strength and plasticity simultaneously. The chemical reactions during the preparation process of the Al-Ti-Sc master alloy was studied by thermodynamic software of HSC 6.0. The content of Sc and Ti in the master alloy reaches 2.48 wt% and 1.4 wt%, respectively, on proper experimental conditions, and the main phases of the master alloys are α-Al and Al 3 (Sc,Ti) phase. In the refined alloys, the average grain size can reach 27 μm, and the ultimate tensile strength and the elongation after fracture reaches 280 MPa and 35% in cast state, respectively. Compared to the pristine 6016 aluminium alloy, the significantly enhanced strength and good plasticity of the refined alloys contribute to the combined effects of grain refinement and precipitated phase strengthening. For the fracture of low doped alloys, originates from cleavage fracture mechanisms, and for the ones with high dosages, ductile fracture becomes dominant. [Display omitted] • A series of ternary Al-Ti-Sc master alloys were prepared by thermite reduction of Sc 2 O 3 and TiO 2. • The effects of technical factors on Sc and Ti contents were researched during the thermite reduction process. • The main second phase in Al-Ti-Sc master alloys is a well-matched Al 3 (Sc,Ti) solid-solution phase. • Both strength and plasticity of 6016-based alloys are improved significantly by addition of Al-Ti-Sc master alloys. • The strengthening mechanisms of the refined 6016-based alloys by Al-Ti-Sc master alloys were clarified. [ABSTRACT FROM AUTHOR]

This study rigorously examines the AA1060 aluminum alloy's mechanical properties across different thermal conditions (298K–77K) and orientations (RD-ND and TD-ND). Through annealing at 350 °C for 50 min followed by extensive mechanical testing at ambient and cryogenic temperatures, the study delves into the microstructural evolution and deformation mechanisms utilizing Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Findings indicate a pronounced increase in yield strength, tensile strength, and ductility with decreasing temperature. Notably, RD-ND oriented samples demonstrated enhanced mechanical strength over TD-ND oriented samples under both temperature regimes, underscoring the alloy's pronounced anisotropy. This comprehensive study illuminates the AA1060 alloy's temperature-dependent mechanical enhancements and anisotropic behavior, emphasizing the significant impact of microstructural orientation on its mechanical properties. The insights gained illuminate the AA1060 alloy's temperature-dependent and anisotropic behaviors, highlighting microstructural orientation's important role in its mechanical properties, with profound implications for aluminum alloy application across varying temperature and stress conditions. [ABSTRACT FROM AUTHOR]

• Ti6Al4V/AA2024 alloy component is fabricated based on interweaving structure. • The compressive shear strength of the Ti6Al4V/AA2024 alloy component is 86.1 MPa. • The Ti6Al4V/AA2024 alloy component's shear strength is 79 % of as-deposited AA2024. • The fracture occurs in the interweaving layer in shear tests. The presence of brittle intermetallic compounds (IMCs) can easily lead to cracks at the interface of titanium/aluminum alloy components. A novel interweaving structure was proposed and a Ti6Al4V/AA2024 dissimilar alloy component was prepared. The interlocking between Ti6Al4V and AA2024 mitigates the adverse effects of brittle IMCs on the Ti/Al interface, while the interweaving of Ti6Al4V and AA2024 avoids the generation of continuous IMCs. The average compressive shear strength of the Ti6Al4V/AA2024 alloy component is 86.1 MPa, which is 79 % of that of as-deposited AA2024. The fracture occurred in the interweaving layer in shear tests. [ABSTRACT FROM AUTHOR]

We study the phase stability of the B2 phase in a two-phase Al 0. 5 NbTa 0. 8 Ti 1. 5 V 0. 2 Zr refractory high entropy alloy. We find that the ordered phase of this alloy primarily contains Zr, Al, and Ti, where Zr and Al occupy opposite sublattices. Although the site occupancy of Ti is not conclusive from the experiments, first-principles calculations confirm the preference of Ti atoms to occupy the Zr sublattice. We also find that the B2 phase composed of Al, Zr, and Ti is unstable and that it transforms into Zr 5 Al 4 Omega, L 1 0 , or an ordered hexagonal phase depending on strain and the presence of antisite defects. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mg-Gd master alloy has a significant modification effect on eutectic silicon of Al-Si alloy. • The mechanism of modification of eutectic Si by Mg-Gd master alloy is twin groove mechanism. • The 1.0wt.%Mg-Gd master alloy can improve the mechanical properties of Al-Si alloy. In this study, the modification of eutectic Si was carried out by adding Mg-Gd master alloy to Al-10Si aluminum alloy. The influence mechanism of Mg-Gd master alloy modification Si on the morphology, size and mechanical properties were studied. The results show that the Mg-Gd master alloy has a remarkable modification effect on eutectic Si, with the average length of eutectic silicon changing from 11.71 μm to 1.95 μm. A large number of twin bands appear in eutectic Si after modification, and the modification mechanism is mainly twin plane reentrant edges. After modification, the mechanical properties are improved significantly and the fracture mode is mainly quasi cleavage fracture. [ABSTRACT FROM AUTHOR]

• Area density could be reduced by explosively welding Mg to Al. • Impact causes delamination in the clad material with a thickness ratio of Mg: Al = 0.7: 0.3. • Compared to A6061-T6, clad material with a thickness ratio of Mg: Al = 0.5: 0.5 produces less forward ejecta. • Shielding performance can be enhanced by increasing the damage area in rear wall using Mg/Al clad material. In this study, we propose the use of a clad material, created from aluminum alloy A1100P-H24 and magnesium alloy AZ31B-H24 through explosive welding, as a Whipple shield for space applications. Two kinds clad materials with thickness ratios of Mg: Al = 0.5: 0.5 and Mg: Al = 0.7: 0.3 made from explosive welding, are compared to the current standard, the 1 mm thick A6061-T6 Whipple shield utilized in the international space station. By explosive welding low density, high specific strength, and high impact strength magnesium alloy with aluminum alloy, clad materials achieved 16.8% and 23.7% reduction in area density compared to A6061-T6. In the context of space debris mitigation, we performed hypervelocity impact tests on these clad materials. Detailed comparisons were made between the impact characteristics of the explosive welded clad materials and A6061-T6 by examining the perforation hole size and shape, and by collecting and analyzing the ejecta produced during impact. The experimental results revealed that the clad material with the thickness ratio of Mg: Al = 0.7: 0.3 experienced delamination at the material interface due to the penetration of projectile. On the other hand, the Mg: Al = 0.5: 0.5 clad material exhibited a perforation hole pattern comparable to that of monolithic aluminum and magnesium alloy materials. The cumulative number distribution of ejecta indicated that the clad material with a Mg: Al = 0.5: 0.5 ratio could reduce ejecta production. To further evaluate interface delamination, post-impact ultrasonic analyses were performed on the clad materials. [ABSTRACT FROM AUTHOR]

Titanium is a highly valued material. Developing a lower-cost titanium (Ti) metal powder production process, potentially substituting the conventional Kroll-HDH method, has challenged the titanium community for decades. The ease of aluminum forming alloys with titanium and the strong chemical affinity of titanium to oxygen rule out the possibility of fabricating pure Ti metal directly by aluminum reduction of TiO 2. Based on the demonstrated enhanced deoxidation of Ti using Mg metal, this paper proposes an Al–Mg combined stepwise reduction of TiO 2 to fabricate Ti metal powder. Critical challenges overcome in this research include predicting reaction thermodynamics and preparing Ti 2 O intermediate by Al reduction of TiO 2 without significant Al alloying, which is made possible by forming mild-acid soluble Ca 12 Al 14 O 32 Cl 2 byproduct. Various Al reduction conditions were investigated and optimized. To the best of our knowledge, it is the first report to fabricate Ti 2 O powder by Al reduction of TiO 2 with a highly stable chemical composition. The difficulty of sintering the Ti 2 O intermediate before Mg deoxidation to reduce the surface oxygen contribution is mitigated by mixing a certain amount of low-oxygen titanium powder with the Ti 2 O powder. This allows the densification temperature to be lowered from 1400 °C for sintering pure Ti 2 O powder to 1100 °C. Even with as much as around 15 wt% oxygen, the sintered powder can be effectively deoxidized by Mg with the help of hydrogen. A titanium metal powder with an oxygen content of 0.134 wt%, an Al content of 0.123 wt%, and other impurities meeting the standard of pure titanium metal powder (GB/T 34486-2017 FTA1) is successfully prepared by the Al reduction-Mg deoxidation combined process. It is a promising alternative for producing titanium metal powder and its derivatives. [Display omitted] • An Al-Mg combined stepwise reduction of TiO 2 to fabricate Ti metal powder is described. • A novel Al reduction-acid picking process helped by CaO and CaCl 2 was built. • Ti 2 O powder with a low Al content was successfully prepared by Al reduction of TiO 2. • A strategy to mitigate the difficulty of direct densification of Ti 2 O was achieved. [ABSTRACT FROM AUTHOR]

The buckling behaviour of combined shells fabricated from aluminium alloy and carbon fiber–reinforced polymer (CFRP) composites subjected to external hydrostatic pressure were investigated. Three sets of combined cylindrical shells with different combinations and one set of bare aluminium alloy cylindrical shells were designed and fabricated. The wall thickness of each cylindrical shell was measured. All the cylindrical shells were tested under external hydrostatic pressure, and the buckling load and final collapsed mode were recorded. Numerical models with real imperfections were established, linear and nonlinear analyses were performed to evaluate the buckling loads of cylindrical shells. The experimental and numerical results agreed favourably. On this basis, the effects of the thickness-diameter ratio, combination method and geometric imperfection on the buckling of combined cylinders were studied. This research can provide a reference for the design of combined shells made from CFRP and metal shell. • The geometry and buckling of 8 combined cylinders were tested. • The effects of the thickness-diameter ratio, combination method and geometric imperfection on the buckling of combined cylinders were discussed. • The failure mode of carbon fiber–reinforced polymer composite combined shell was discussed. • The numerical results are in good agreement with experimental results (within 8 %). [ABSTRACT FROM AUTHOR]

The effects of pre-soaking in seawater on the corrosion behaviour of the nickel aluminium bronze alloy were examined using electrochemical and erosion-corrosion tests. The surface passive film of the alloy pre-soaked for 30 d consisted of an outer loose CuO film, a middle dense Cu 2 O film, and a denser inner Cu 2 O film contained Al 2 O 3. The corrosion properties of the sample pre-soaked for 30 d were significantly improved, with ∼71% reduction in corrosion rate at 3 m/s compared with the unsoaked sample. Strong bonding between the substrate and passive films formed during pre-soaking effectively inhibited the entry of ions from seawater. • The pre-soaked sample surface corrosion film is divided into three layers. • The middle and inner layers are composed of dense Cu 2 O and thin Al 2 O 3 for protection. • The pre-soaked corrosion film has stronger adhesion to the substrate after erosion. • Significant improvement in erosion-corrosion performance of pre-soaked film sample. [ABSTRACT FROM AUTHOR]

• Barrier layer thinning of anodic films formed on aluminum alloys is a new challenge. • A simple barrier layer thinning step was studied after a single-step anodizing. • The thinning step was carried out in galvanodynamic mode with a constant scan rate. • Using an adequate rate, barrier layer thinning is controlled at the nanometric scale. • Barrier layer drilling opens the way for new post-treatments of functionalization. Thinning the barrier layer thickness of anodic films prepared on refined aluminum substrates (4 N or 5 N) was usually performed to elaborate -after the usual two-step anodizing method- anodic aluminum oxide (AAO) templates with pores opened at both sides, allowing the subsequent nanodevices synthesis. By contrast, there is a lack of studies concerning similar barrier layer thinning for anodic films grown -by a single-step anodizing - on commercial low alloyed aluminum substrates (1XXX series) or other more complex aluminum alloys (AA 2XXX-8XXX). Yet such a need is now emerging, particularly for future applications requiring transverse electrical conductivity of usual anodic films toward the aluminum alloy substrate. This work aims to study and to master a simple and cheap method for thinning the barrier layer thickness of such anodic films on commercial aluminum alloys. Here, the thinning is studied using a current density decrease (at a constant rate) after the anodic film growth in phosphoric acid-based electrolyte, using the conjunction of in-situ accurate electrochemical follow-up and ex-situ FE-SEM morphological observations. Variation of current density scan rate highlights that fast processes lead to no barrier layer thinning, and slow ones to the detachment of the whole oxide film. However, by choosing the right scan rate range, it is possible to successfully obtain, in a straightforward manner, anodic films still supported on aluminum alloy substrates, but with barrier layer thickness tuned at the nanoscale. [Display omitted] [ABSTRACT FROM AUTHOR]

• The static shear and fatigue performance of CFRP/aluminum alloy adhesive joint was studied. • The effect of size parameters on the mechanical property and failure behavior was clarified. • The fatigue failure mechanism of CFRP/aluminum alloy adhesive joint was revealed. The size parameter is quite significant for the performance of adhesive joint. In order to investigate the effect of size parameters on the mechanical property and failure behavior of CFRP/aluminum alloy single-lap adhesive joint, T300 CFRP laminate and AA5182 aluminum alloy sheet were bonded by Sika Power 497 structural adhesive under different size parameters. The quasi-static shear test and fatigue test were implemented, and the failure behavior and failure mechanism were analyzed. Results showed that the increase of aluminum alloy sheet thickness or bonding area length could effectively improve the bonding strength of adhesive joint, when the strength of the aluminum alloy sheet or the adhesive layer was insufficient. The shear failure modes of adhesive joint mainly included adhesive failure, base material failure and mixed failure. The fatigue failure modes of adhesive joint were mainly adhesive cohesion failure and adhesive adhesion failure. At low stress levels, the aluminum alloy sheet might fracture. In addition, this work can provide a scientific guidance for the engineering application of adhesive bonding technology. [ABSTRACT FROM AUTHOR]

Electron beam physical vapor deposition (EB-PVD) with high power axial EB guns has high deposition rates and therefore is well suited for depositing comparatively thick coatings with high throughput in mass production processes. The top sliding layer on bearing shells is a well-known use case for this technology. In low-cost manufacturing, often semi-finished products such as sheets or strips are coated, from which final products with a broad range of dimensions can be manufactured. The adaptation of related processes such as pretreatment and substrate cooling of three different semi-finished products was the focus of the investigations. All process steps were optimized for high throughput. Deposition with AlSn or AlSnCu alloys was carried out at coating rates up to 1 μm/s. These alloys, containing elements with different vapor pressures, were evaporated out of one continuously fed crucible with long-term stability. The deposited coatings have finely dispersed tin clusters in the aluminum matrix. The tin clusters have linear dimensions in the range of 200 to 400 nm. This size range is a direct consequence of the high coating rate; it is thus process-specific for EB-PVD. Such coatings are highly beneficial for applications such as plain bearings. Initial load tests have impressively confirmed the advantages for EB-PVD processed bearings. • Aluminum-tin alloys were deposited by EB-PVD at a static deposition rate of up to 1 μm/s. • The pretreatment process and substrate cooling have been optimized for high throughput. • The technology has been adapted to different types of semi-finished products: bearing shells, metal sheets, and strips. • The AlSn coatings have finely dispersed tin clusters with linear dimensions ranging from 200 to 400 nm. • Initial load tests showed a high load capacity of the manufactured bearings. [ABSTRACT FROM AUTHOR]

• The laser-cladded Cu-Ni-Cr alloy coating was prepared on aluminum alloy substrate. • The shear strength of Cu-Ni-Cr alloy coating is larger than the substrate. • The Cu-Ni-Cr alloy coating has excellent resistance to galvanic corrosion with TC4. The Cu-Ni-Cr alloy coating was prepared on 5083 aluminum alloy substrate using laser cladding technology. The microstructure of the coating and its galvanic corrosion resistance in contact with TC4 alloy were studied. The results indicate that the Cu-Ni-Cr alloy coating primarily consists of Al-rich dendrite phase and Cu-rich matrix phase. The shear strength of the Cu-Ni-Cr alloy coating is 154.68 MPa, which is greater than that of the aluminum alloy substrate. The galvanic current density of the TC4/Cu-Ni-Cr couple is 0.05 μA·cm−2. The neutral salt spray corrosion test results demonstrate that the Cu-Ni-Cr alloy coating exhibits excellent resistance to galvanic corrosion. The coating can attenuate the galvanic corrosion effect when it is in contact with the TC4 titanium alloy, offering new solutions to address the galvanic corrosion challenges between titanium alloy and aluminum alloy in marine environments. [ABSTRACT FROM AUTHOR]

• The joint quality of perforated CFRP and aluminum alloy stick-self-punch riveting was studied. • The static characteristics and the failure modes of the joint were analyzed. • Results showed that the main failure mode of HH-BR joint was laminate tearing. • The reasons why HH-BR joints have better performance than H-BR and SPR joints were explained. This paper explores the new hybrid hole-drilled bonding and self-piercing riveting (HH-BR) connection technique to enhance the strength and overall performance of carbon fiber reinforced polymer (CFRP) and dissimilar metal materials at joint interfaces. The forming quality, mechanical performance, failure modes, and fracture characteristics of the CFRP and aluminum alloy joints utilizing the HH-BR procedure were analyzed in detail and compared with the joints of the hole-less adhesive-bonding self-piercing riveting (H-BR) and self-piercing riveting (SPR). At the same time, the effects of different rivet performance levels, overlap lengths, and various fiber orientation angles on joint performance were discussed. The results show that joints made by the HH-BR technique have a substantial advantage in terms of achieving superior mechanical performance and interlocking value. Firstly, HH-BR joints with bent rivets and torn fibers have connection strengths that are noticeably higher than those with CFRP laminate delamination or rivet pullout failure. The use of the HH-BR technique for joining CFRP/aluminum alloy culminated in reduced strength loss and higher energy absorption than H-BR and SPR joints, improving the joint's overall strength. Secondly, the interlock value between the rivet and the plate, is what essentially determines the strength of HH-BR joints, especially evident in connections with 0°/90° fiber orientation and more overlap lengths. The results also show that there is a strong relationship between the height of the rivet head and the joint's mode of failure, and the height of the rivet head is affected by the rivet force. Furthermore, the interlock value's magnitude, the joint's remaining bottom thickness, and the metal material's capacity for plastic deformation are all directly correlated. [ABSTRACT FROM AUTHOR]

The pitting potential, intrinsic surface acidity, point of zero charge of passive film on Al are studied using first-principles calculations to establish their relationships. Influences of alloying elements Zn, Cr, Nb, Si, Mo and Sc on adsorption of NH 3 and NaCl, pH pzc of Al 2 O 3 and pitting susceptibility of Al are investigated. The efficiency for enhancing pitting resistance of Al is evaluated, yielding the ratios Si: Zn: Cr: Mo: Nb: Sc = 1.8: − 0.3: 1: 1.9: 1.4: 0.2. A model for the dependence of pitting potential on the concentration of alloying elements in Al alloy matrix is developed, based on effects of alloying elements on the surface charge of passive film. The effects of Sc on pitting potential and pH pzc of Al oxide are predicted based on the calculated results, which are supported by electrochemical measurement, XPS analysis and contact angle titration. • Correlations between pitting potential and surface acidity, pH pzc of passive film on Al alloy are proposed. • We develop a model for the linear dependence of pitting potential on alloying element contents in Al alloy matrix. • The efficiency for Zn, Cr, Nb, Si, Mo and Sc to enhance pitting resistance of Al alloy is theoretically predicted. [ABSTRACT FROM AUTHOR]

Many additively manufactured alloys exhibit higher strengths than compositionally identical alloys processed via conventional processing routes. However, this enhancement is not consistently observed in 7xxx series aluminum alloys. These alloys present two complications when printed via Laser Powder Bed Fusion (LPBF): significant evaporation of strengthening elements from the melt pool and hot cracking during solidification. To address these issues, we introduce two modifications to the feedstock powder: (i) we increase the concentration of alloying constituents to counteract evaporation during printing, and (ii) we disperse TiC nanoparticles within the feedstock powder to promote heterogeneous nucleation and limit grain growth, thus avoiding hot cracking and improving strength. Relationships between the evaporation of alloying elements and laser energy density are quantified experimentally using inductively-coupled-plasma mass-spectrometry and are well captured by simple analytical models. The microstructures in as-printed and heat-treated conditions are characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Printing parameters have been optimized to attain minimum porosity, resulting in tensile strengths up to 650 MPa, which are in good agreement with predictions from classic models of strengthening mechanisms. [ABSTRACT FROM AUTHOR]

Effects of neutron irradiation on the microstructure and mechanical properties of CMRR (China Mianyang Research Reactor) structural material pure aluminum and 6061 alloy were studied by scanning/transmission electron microscopy (S/TEM) and tensile tests. The fast neutron (E > 0.1 MeV) fluences of 1.09–2.89 × 1022 n•cm−2 produced damage doses of 1.6–4.2 displacements per atom (dpa). Voids and faulted 1/3<111> dislocation loops were observed in both pure aluminum and 6061 alloy. In particular, voids tended to preferentially aggregate on coarse Cu-rich and fine Mg 2 Si precipitates which contributes to the higher irradiation tolerance in terms of void formation for 6061 alloy, suggesting that the uniformly distributed precipitates can act as trapping sites for defect clusters during irradiation and thus promote recombination. The size and density of Mg 2 Si precipitates showed a slight increase and Cu-rich precipitates emerged in 6061 alloy after neutron irradiation. Moreover, radiation-induced segregation was also detected along the grain boundaries. After tensile testing, the pure aluminum showed a lower yield strength and larger uniform elongation than 6061 alloy, where a moderate uniform elongation was still reserved after irradiation to 4.2dpa. The severely reduced ductility in 6061 alloy is supposed to be caused by the transmutation product silicon which contributes to the increase of dispersed multiple precipitates after irradiation. Our results indicate that precipitates especially Mg 2 Si play a decisive role in void suppression, but are not suitable in diminishing the radiation hardening. [ABSTRACT FROM AUTHOR]

Nickel aluminium bronze alloy specimens were produced using laser powder bed fusion (LPBF) and subjected to heat treatment to understand their corrosion behaviour when exposed to a 3.5 wt% NaCl solution. Electrochemical analysis, including impedance spectroscopy and polarization curves, was performed to characterize the samples after 30 days of immersion. The findings reveal that the as-built samples exhibit superior corrosion resistance compared to the heat-treated samples, primarily attributed to the lower presence of intermetallic phases, which hinder the alloy's passivation process. • NAB produced via AM exhibit lower corrosion current densities than thr heat-treated. • The microstructure and corrosion behavior of NAB is significantly influenced by fabrication methods and heat treatment. [ABSTRACT FROM AUTHOR]

• Rapid preparation of porous graphite skeletons using selective laser sintering (SLS) molding technology. • Three-dimensional bicontinuous graphite/aluminum alloy composites were prepared using vacuum pressure casting. • The three modulations of flexural strength, thermal conductivity and thermal expansion coefficient of the composite are achieved by adjusting the volume fraction of porous graphite skeleton. • When the volume fraction of porous graphite skeleton is 55 %, the bending strength of three-dimensional bicontinuous graphite/aluminum alloy composite reaches 75.8 MPa, thermal conductivity (TC) reaches 116.84 W/m K, and coefficient of thermal expansion (CTE) reaches 6.11 × 10-6 K−1, which is expected to be a potential thermal management material. In this paper, porous graphite skeletons were rapidly prepared using selective laser sintering (SLS) molding technique. After several vacuum impregnation reinforcements, carbonization, graphitization and surface modification, the porous graphite skeleton has good compressive strength and thermal-physical properties. A356 aluminum alloy was compounded with porous graphite skeleton by vacuum extrusion casting method to obtain three-dimensional bicontinuous graphite/aluminum alloy composites. The effects of vacuum impregnation reinforcement on the comprehensive properties of the porous graphite skeleton were investigated, and the bending strength, thermal conductivity (TC) and coefficient of thermal expansion (CTE) of the three-dimensional bicontinuous graphite/aluminum alloy composites were regulated by changing the volume fraction of the porous graphite skeleton. In the composites, the porous graphite skeleton bonded well with the aluminum alloy interface. The various properties of the composites showed significant anisotropy of each by the influence of the porous graphite skeleton. When the volume fraction of porous graphite skeleton is 55 %, the bending strength of three-dimensional bicontinuous graphite/aluminum alloy composite reaches 75.8 MPa, TC reaches 116.84 W/m K, and CTE reaches 6.11 × 10-6 K−1, which is expected to be a potential thermal management material. [ABSTRACT FROM AUTHOR]

The mechanical properties and stress corrosion cracking (SCC) resistance of 7xxx series aluminium alloys are significantly affected by the composition and distribution of precipitates formed during heat treatment. In particular, their quench sensitivity is related to the formation of η-phase precipitates that nucleate heterogeneously on grain boundaries at lower cooling rates after solution treatment, which has been a key factor restricting the gauge of hot rolled plates in the aerospace industry. To better understand the effects of slower cooling rates on the composition of quench-induced grain boundary precipitates (Q-GBPs) found in thick plate 7xxx alloys, plasma focused ion beam and high-resolution scanning transmission electron microscopy were used to obtain accurate composition data. The η-phase Q-GBPs have a complex- branched morphology, which develops higher aspect ratios and secondary arms as the cooling rate is reduced. Only a small change in average composition of Q-GBPs was found with cooling rate; but a large scatter was observed. This is caused by significant Zn/Cu/Al composition gradients developing along their principal growth directions in both AA7050 and AA7085 alloys. This concentration gradient did not reduce significantly after a T76 treatment. Simulations of Q-GBP growth with different cooling rates using a CALPHAD-informed phase-field model, with the η-phase represented by a two-sublattice model, gave results consistent with experimental observations. Chemical gradients were predicted to develop in the Q-GBPs due to the changing local equilibrium at the growth front during the cooling. The influence of this non-homogeneous microchemistry on the SCC behaviour of 7xxx alloys is briefly discussed. [Display omitted] [ABSTRACT FROM AUTHOR]