Aluminum Structures Research Articles

Molecular dynamics study of the dissolution of crystalline and amorphous nickel nanoparticles in aluminium

Abstract The dissolution of a nickel nanoparticle in aluminium under the conditions of the crystalline and amorphous state of aluminium and nickel, which can be achieved, in particular, with severe plastic deformation of the powders of the initial mixture (mechanoactivation), was studied by means of molecular dynamics. It is shown that the state of the aluminium structure (crystalline or amorphous) has a relatively small effect on the intensity of mutual diffusion of Ni and Al up to the melting temperature of aluminium. This is due to the formation of a crystalline aluminium layer around the crystalline particle, which repeats the Ni lattice. In the case of the amorphous state of the nickel particle and the aluminium matrix, dissolution occurred much faster than in the crystalline state of nickel. That is, mutual diffusion occurs significantly more strongly in the case of the amorphous state of nickel compared to the case of amorphous aluminium at the same constant temperature. The diameter of the nickel nanoparticle in the considered range from 4 to 12 nm did not affect the temperature at which the mutual diffusion of Ni and Al sharply accelerated with varying temperature. This was due to the fact that the melting point of aluminium did not change when simulating particles of different sizes.

Vapour phase deposition of phosphonate-containing alumina thin films using dimethyl vinylphosphonate as precursor.

Phosphorous-containing materials are used in a wide array of fields, from energy conversion and storage to heterogeneous catalysis and biomaterials. Among these materials, organic-inorganic metal phosphonate solids and thin films present an interesting option, due to their remarkable thermal and chemical stability. Yet, the synthesis of phosphonate hybrids by vapour phase thin film deposition techniques remains largely unexplored. In this work, we present successful deposition of phosphonate-containing films using dimethyl vinylphosphonate (DMVP) as a phosphonate precursor. Two processes have been studied, being a three-step process comprising alternating exposure to trimethylaluminum (TMA), water (H2O) and DMVP (ABC process), and a four-step process with an extra O3 step following the DMVP pulse (ABCD process). The O3 treatment is employed for in situ functionalisation of the adsorbed phosphonate precursor, transforming the vinyl group into a carboxylic acid end group. For both processes, good precursor saturation was found, with the ABCD process exhibiting a more stable growth per cycle (0.54-0.38 Å per cycle) in the investigated temperature range (100-250 °C). Phosphonate features were visible in FTIR spectra for both films, with the ABCD films also exhibiting a carboxylate signal. XPS showed a higher P incorporation in the ABCD films deposited at 250 °C, although still moderate (P/Al = 0.27), consistent with an alumina structure with phosphonate inclusions. The film stability upon immersion in water was tested, showing a slow oxidation over the course of a week. Finally, annealing experiments in air demonstrated stable films up to 400 °C.

EFFECT OF CALCINATION TEMPERATURE ON THE PHASE COMPOSITION AND MAGNETIC PROPERTIES OF THE BOEHMITE WITH ADSORBED FERROCENE

The effect of calcination temperature in air of finely dispersed boehmite powders with ferrocene adsorbed at room temperature from n-hexane solution on X-ray diffraction patterns and EPR spectra of calcined samples was studied. It has been shown that calcination in air of boehmite samples with adsorbed ferrocene leads to the decomposition of ferrocene molecules, stabilization of two types of magnetic centers in the structure of boehmite (at 200 and 400°C) and aluminum oxide (at 600°C) caused by two types of magnetic centers -Fe3+ ions with g-factor values, equal to 4.3 and 2.0. The signal at g = 4.3 is attributed to isolated Fe3+ ions in the structure of boehmite and aluminum oxide in a local field of oxygen anions with a rhombic environment. The signal at g = 2.0 is most likely due to Fe3+ ions bound by dipole interaction for samples with a low concentration of supported ferrocene (<0.1 wt.%) and superpara/ferromagnetic FeOx particles for samples of the calcination product of boehmite with a high content (>0.1 wt.%) of ferrocene. With increasing content of adsorbeded ferrocene, concentrations of Fe3+ ions with g-factor values equal to 4.3 and 2.0 grow disproportionately, and mainly the growth of the concentration of superpara/ferromagnetic FeOx particles on the oxide surface is observed.

High-strength aluminum matrix composites with strong bonding interfaces via in-situ amorphous alumina and plainification strategy

Silicon carbide particle (SiCp) reinforced aluminum matrix composites have potential applications for components under severe service conditions. However, their performance is commonly limited by challenges such as insufficient interfacial bonding strength, agglomeration and brittle interfacial reaction products. In this paper, the ultra-fine grained aluminum and in-situ formed amorphous alumina were fabricated, and the as-formed powder metallurgy SiCp/Al composites achieved excellent properties, with a high yield strength of 471 MPa and an ultimate tensile strength of 505 MPa, respectively. We systematically investigated the structures of the amorphous alumina, which bonds the SiCp and matrix together, improving the interfacial bonding strength and simultaneously suppressing the interfacial reactions. Notably, the proposed fabrication method is suitable for economic production of large-scale components and applicable for aluminum matrix composites with other types of reinforcements.

Crashworthiness Performance Study of 3D-Printed Multi-Cell Tubes Hybridized with Aluminum Under Axial Quasi-Static Testing

This study investigates the crashworthiness performance of 3D-printed hybrid tubes, fabricated using PLA and PACF filaments with varying shell thicknesses (1, 1.5, and 2 mm). The hybrid tubes, composed of a shell, aluminum, and multi-cell structure, were subjected to axial quasi-static testing. Results indicate that both shell thickness and filament type significantly influence crashworthiness. PLA specimens with a shell thickness of 2 mm absorbed 504 J of energy, whereas PACF specimens with the same thickness absorbed only 342.9 J. The deformation mode analysis revealed mixed deformation patterns, including diamond, fracture, and fragmented modes. The study also evaluated specific energy absorption (SEA) and crushing force efficiency (CFE). The PLA specimen with a 2 mm shell thickness exhibited the highest SEA value of 18.61 J/g among all specimens. In contrast, the PACF specimen with the same shell thickness demonstrated the highest CFE value of 0.82 among the tested specimens. Overall, this research contributes insights into the design optimization of 3D-printed hybrid tubes for enhanced crashworthiness.

Delamination and thrust force analysis in GLARE: Influence of tool geometry and prediction with machine learning models

The multi-layered (fiber/metal) structure of glass fibre aluminium reinforced epoxy (GLARE) makes it difficult to obtain acceptable damage-free holes that meet aerospace standards. This paper investigated the effects of tool geometry and drilling parameters on reducing delamination damage and uncut fibers at the hole exit surface in drilling GLARE. The hole surfaces were examined by scanning electron microscope (SEM) at various magnifications. In addition, deep neural network (DNN) and long-short-term memory (LSTM) machine learning models were used to predict delamination (Fda), uncut fiber (UCF), and thrust forces using experimental data. No positive contribution of the special geometry tool was observed, while the standard geometry tool was found to be ideal for drilling conditions. Analysis of variance (ANOVA) revealed that feed rate contributed 57.83% to delamination damage, while tool geometry contributed 74.31% and 92.33% for uncut fiber and thrust force, respectively. SEM analysis revealed high deformation zones in the aluminum layers and fiber fracture and separation in the glass fibre reinforced polymer (GFRP) layers. DNN and LSTM models were found to provide accurate predictions with R2 values greater than 95% and 98%, respectively.

Multimodal defect analysis and application of virtual machining for solid-state manufactured aluminium structure

AbstractAdditive friction stir deposition (AFSD) is an emerging solid-state non-fusion additive manufacturing (AM) technology, which produces parts with wrought-like material properties, high deposition rates, and low residual stresses. However, impact of process interruption on defect formation and mechanical properties has not yet been well addressed in the literature. In this study, Al6061 aluminium structure with two final heights and deposition interruption is successfully manufactured via AFSD and characterised. Defect analysis conducted via optical microscopy, electron microscopy, and X-ray computed tomography reveals > 99% relative density with minimal defects in centre of the parts. However, tunnel defects at interface between substrate and deposit as well as kissing bonds are present. Edge of deposit contains tunnel defects due to preference for greater material deposition on advancing side of rotating tool. Virtual machining highlights the ability to remove defects via post-processing, avoiding mechanical performance impact of stress concentrating pores. Electron backscatter diffraction revealed regions with localised shear bands that contain 1–5 µm equivalent circular diameter grains. Kissing bonds are exhibited in areas separated by large grain size difference. Meanwhile, Vickers hardness testing reveals hardness variation with deposit height. This work advances the understanding of complex microstructure development, material flow, and mechanical behaviour of AFSD Al6061 alloy.

ETHos – A Swiss‐Made Open‐Source Modular Photoreactor for Laboratory‐Scale Photochemical Reactions

AbstractThe emergence of photoredox chemistry has enabled the development of previously inaccessible synthetic transformations. Despite the popularity of photoredox chemistry, commercial photoreactors remain expensive. As a result, most academic research groups resort to self‐built, not easily replicable reactor designs, jeopardizing the reproducibility and accessibility of photochemical research. To address these issues, this work introduces an easily replicable and modular open‐source photoreactor optimized for lab‐scale photochemical synthesis. The reactor is operationally simple, operates consistently and reproducibly, and is inexpensive to manufacture. Our design integrates active temperature regulation, an exchangeable vial rack, and customizable light sources into a hybrid structure of machined aluminum, 3D‐printed parts, and commercially available components. The open‐source reactor with detailed 3D CAD files on GitHub is designed to make research in the field of photochemistry more accessible and reproducible.

A novel electromagnetic self-pierce upsetting riveting with flat die for joining ultra-high strength steel and aluminum structures

A novel electromagnetic self-pierce upsetting riveting with flat die for joining ultra-high strength steel and aluminum structures

Steel‑aluminum clinched joints mechanical properties and strength prediction under different geometric parameters

With the evolution of modularization and prefabrication in construction, there is a growing adoption of prefabricated thin-wall steel and aluminum structures for lightweight buildings and interior decoration. Clinching emerges as a proficient method for achieving heterogeneous metal connections, offering benefits such as streamlined processes, reduced material usage, environmental friendliness, and potential for automation. This study focuses on high-strength steel DP590 and aluminum alloy AW5754-H22, exploring various process parameters (including punch diameter, punch fillet radius, extensible die diameter, and extensible die depth) tailored for clinching experiments on thin steel and aluminum plates. The research analyzes how these process parameters affect the geometric characteristics of the joints and investigates their mechanical properties through static shear tests. Findings indicate that interlocks exceeding 0.29 mm lead to neck cracks during the clinching process. Additionally, the energy absorption of the specimens in button separation exceeds that in neck fracture by 44 % under comparable maximum failure loads in static shear. Optimal process parameters identified are SR5605-SR60310, achieving a maximum failure load of 4.14kN and an energy absorption value of 12.37 J in static shear tests. Finally, a method is proposed to calculate the shear strength of steel‑aluminum clinched joints based on the transmission dynamics of infectious diseases model (SIR model), accounting for the influence of geometric parameters on the static performance of the joints. This approach accurately describes the load-displacement curve trend and predicts the static shear strength of steel‑aluminum clinched joints effectively.

Analysis of the Influence of Adhesive, Geometry, and Manufacturing Processes on Mixed Mode Stress Ratio in Single Lap Shear Adhesive Joint Structures of Aluminum and Composite Plates

In aircraft structures, composite plate joints often present significant challenges. Mechanical fastenings such as pins, bolts, or rivets require holes to be drilled in the plates, which reduces the strength of the laminate due to stress concentrations around the hole edges. These joints frequently become sources of structural failure in aircraft. Therefore, the design of composite plate joints is crucial to maintain structural integrity. Adhesive joints offer several advantages over mechanical joints, including the ability to join two different materials, more uniform stress distribution along the joint, and reduced weight since no bolts or rivets are needed. The most common adhesive joint design is the Single Lap Joint (SLJ), which is popular due to its simple geometry and high structural efficiency. However, the main drawback of the SLJ is load eccentricity, which leads to secondary bending and undesirable normal stresses along the adhesive edges. The hypothesis of this study is that SLJ conditions with optimal shear strength can be achieved through the right combination of adhesive type, bond surface preparation, and joint configuration. This study analyzes the influence of various adhesive materials, joint designs, and manufacturing methods using numerical modeling methods, validated with analytical approaches and ASTM standard testing. Numerical modeling is conducted using the finite element method with a cohesive zone model (CZM) approach to examine stress distribution in various cases, such as the impact of geometry, adhesive thickness, and joint length. The normal and shear stress distribution along the joint is found to significantly affect the strength of the SLJ, highlighting the importance of careful design and material selection in these applications.

Formation Efficiency of Anodic Alumina in Acidic Electrolyte Containing Amino Acid

Anodic porous alumina films, which are formed by anodization in acidic solution, provide hardness, wear resistance and corrosion resistance for the surface of aluminum used for automobile and aircraft parts. For instance, to increase the hardness of anodic films on aluminum, the anodization is industrially carried out at low temperature to avoid chemical dissolution of the film during anodization. From a perspective of energy conservation and decarbonization, an important objective are to reduce energy costs and improve work efficiency. Our group has reported that the addition of alcohol (e.g., methanol, ethanol, and ethylene glycol) to an electrolyte improves the formation efficiency and hardness of the film at 20 °C 1, 2). In this study, we focused on amino acids that having inhibitability of aluminum corrosion by adsorbing on the surface of aluminum in a mixed acid containing chloride ion 3). The effects of types and concentrations of amino acids on the anodization voltage, formation efficiency (coating ratio) and structure of the porous alumina were investigated. The sulfuric acid and oxalic acid were used as electrolytes, each containing various amino acids (e.g., glycine, α-alanine, and β-alanine). The electrolyte was maintained at a constant temperature of 20 °C using a thermostat and gently stirred at 300 rpm using a magnetic stirrer to accelerate the diffusion of the heat evolved during the anodization.For example, anodization was conducted in 1.5 mol dm–3 sulfuric acid at 100 A m–2. After anodization for 60 min, the final voltage was 15 V. Even when 100 mmol glycine was added to sulfuric acid, the final voltage was almost the same as sulfuric acid alone. For sulfuric acid containing 800 mmol glycine, however, the final voltage (22 V) was higher than that for sulfuric acid alone. When the concentration of amino acid became high, the viscosity of the electrolyte increased, while the conductivity decreased. Even in the oxalic acid-based electrolyte, the tendency of amino acid concentration dependence of voltage was the same as that of sulfuric acid-based electrolyte. These results indicate that the increased final voltage can be attributed to the high solution resistance of the electrolyte used for anodization. The formation efficiency (coating ratio) and hardness of anodic film formed in acidic electrolyte containing amino acids will also be discussed.1) Matsumoto, H. Hashimoto, H. Asoh, J. Electrochem. Soc., 167, 041504 (2020).2) Asoh, T. Sano, J. Electrochem. Soc., 168, 103506 (2021).3) Ashassi-Sorkhabi, Z. Ghasemi, D. Seifzadeh, Appl. Surf. Sci., 249, 408–418 (2005).

Galvanic and Local Corrosion of Aluminum Alloy 6061-T6 Coupled to Non-Passivating and Passivating Alloys

Marine and aerospace structures sometimes combine lightweight aluminum alloys with dissimilar metals to optimize mechanical performance and reduce costs. Unfortunately, the exposure of such dissimilar couples in a harsh environment can cause severe corrosion damage to the aluminum structure due to its position in the galvanic series. Corrosion of Aluminum Alloy (AA) 6061-T6 coupled to non-passivating and passivating alloys was studied to elucidate galvanic effects on local corrosion. In this work, local and galvanic corrosion were quantified, the effects of cathode material on local electrolyte pH were explored, and a relationship between pH and local-corrosion of AA6061-T6 was established.Experimental studies quantified local and galvanic corrosion of AA6061-T6 coupled to 316 stainless steel, copper, titanium alloy Ti6Al4V, and 316 stainless steel coated with titanium nitride, chromium nitride, and a sol-gel nano-coating. Galvanic couples were misted with 3.15 wt.% sodium chloride solution and exposed in a controlled temperature-humidity chamber. Galvanic currents were measured during exposure, and the total mass loss of the aluminum alloy was determined to quantify the corrosion damage. Exposure tests showed that galvanic corrosion decreases over time and accounts for less than 15% of the total corrosion of AA6061-T6. Therefore, most aluminum corrosion damage was caused by local corrosion. In addition, immersion experiments of AA6061-T6 galvanic couples in gelled 3.15 wt.% NaCl solutions showed that galvanic coupling influences the evolution of electrolyte pH leading to severe acidification at the aluminum anode surface and alkalization around the cathode. The solution pH at the aluminum surface was decreased by galvanic action and severity of pH decrease depends on galvanic couple materials and design. To quantify the effect of acidity on local corrosion of AA6061-T6, potentiodynamic polarization tests were performed in aerated and deaerated 3.15 wt.% NaCl solution adjusted to different pH values. Anodic dissolution reactions and cathodic oxygen reduction reactions show significantly higher anodic and cathodic currents for more acidic solutions due to the instability of the passive oxide film of aluminum. This film is stable in near-neutral solutions and unstable in highly acidic solutions. As a result, the breakdown of the passive film increases the effective area contributing to anodic or cathodic currents resulting in enhanced local corrosion.The series of experimental results show that galvanic interaction leads to a decrease of pH at the aluminum anode, and therefore increasing local corrosion of the aluminum surface. The increase of local corrosion induced in a galvanic couple depends on the cathode material and underlines the importance of accounting for local corrosion and pH-dependent corrosion kinetics when predicting the galvanic compatibility of aluminum alloys.

On the role of local reinforcement in an adhesively bonded AL/CFRP energy absorber under axial loading: A theoretical investigation and optimization

AbstractThis paper aims to develop a novel theoretical model that incorporates the effects of local composite reinforcement using adhesive bonding on the energy absorption of aluminum structures under axial loading. The goal is to optimize energy absorption prior to any connection failures and to prevent uneven structural deformation. Moreover, it strives to reduce the structure's weight and material usage, achieving superior results compared to traditional global reinforcement techniques. The theoretical model was validated through experimental testing and finite element analysis, demonstrating good agreement with the predicted results. The results reveal that increasing the CFRP fiber angle, layer thickness, and number of layers generally leads to improved energy absorption capacity. An optimization analysis was performed to determine the optimal design parameters, yielding a fiber angle of 80°–90°, composite thickness of 1.5 mm, and aluminum thickness of 2.5 is the best configuration, offering the highest specific energy absorption and adequate peak load capacity for maximized energy absorption. The proposed model offers significant improvements over existing approaches, enhancing the predictive capabilities and practical applicability of energy absorption predictions in engineering design.Highlights A novel theoretical model for energy absorption in locally reinforced hybrid AL/CFRP structures. The influence of design parameters, such as CFRP layer count, fiber orientation, and thickness ratio. Optimization to maximize the average crushing force while meeting weight and geometric constraints. Findings can inform the design of safer and more efficient energy‐absorbing structures in various applications.

Influence of the stoichiometric ratio of barrier layer alumina on the transport properties of Josephson junctions

In the field of quantum computing, the Josephson junction is one of the main components for generating superconducting qubits. The material defects present in the junction affect the stability and reproducibility of qubits, which consequently limits the performance of quantum computing. In this paper, we conduct a detailed study of the crystal structure of alumina at different stoichiometric ratios and its electrical properties using density-functional theory (DFT). Additionally, we simulate the amorphous structure at various stoichiometric ratios using molecular dynamics methods. Our results show that a decrease in the oxygen content in the crystalline alumina material leads to a linear reduction in the bandgap. We then construct Josephson junction models with different stoichiometric ratios of the barrier layer based on our study, and calculate the equilibrium conductance for each model using the Non-equilibrium Green’s Function (NEGF) method. Our results indicate that the structure of the barrier layer significantly affects the electrical properties of the Josephson junction. Moreover, the stoichiometric ratio of alumina is a critical parameter that results in exponential variations in the equilibrium conductance. In summary, we seek to elucidate the role that variations in the stoichiometric ratio of the oxide play in the transport properties of the junction. Our findings provide a theoretical basis for improving the stability and performance of superconducting qubits.

Design and development of smart AI-based voice assistive ergonomic commode wheelchair for mobility and rehabilitation

This study focuses on enhancing assistive devices for the elderly and disabled, primarily addressing the challenges associated with traditional wheelchairs. While wheelchairs are widely used for basic mobility, the research identifies several issues in existing products, such as a lack of attention to ergonomic features, anthropometric principles, and limited technological interventions. One major concern is the discomfort experienced by users over extended periods, especially when essential design elements like height and back adjustments are neglected. Another challenge highlighted is the issue of defecation, particularly in the absence of a caregiver. This dependency on caretakers can be mentally burdensome for users, raising privacy concerns during such personal activities. To address these issues, this research proposes a solution that integrates ergonomic features and incorporates low-cost technological interventions, including artificial intelligence-based voice assistance. The ultimate goal of this paper is to design and introduce an AI-based voice-assisted ergonomic wheelchair that not only supports basic mobility but also ensures comfort over extended periods. The proposed solution aims to incorporate a commode feature for defecation within a smart ergonomic wheelchair equipped with voice assistance and provide comfort to the user(s). The design prioritizes anthropometric dimensions, ensuring comfort and convenience for users across various age groups. Employing SolidWorks software, a stable and robust model has been designed, and its durability was assessed through stress analysis using the SolidWorks simulation tool by applying a 981 Newton load on the wheelchair's frame using two different materials (steel and aluminum). The maximum stress value is less than the yield strength, and the deformation is 2.57 e+00 mm for the steel frame, indicating that the design is stable and durable compared to the aluminum structure. The proposed voice-assistive, ergonomic, AI-based wheelchair with a commode cavity is a revolutionary development for the healthcare sector in terms of innovation.

Atomic-scale investigation on the structures and mechanical properties of metastable grain boundaries in aluminum

Grain boundary (GB) structural transition in pure metals open up new possibilities for material microstructure design. By managing the distribution of ground-state and metastable GB structures, the beneficial effects of GBs on materials can be maximised. However, the application of GB transitions to develop high-performance aluminum is limited by the inadequate understanding of the metastable GB structure in aluminium and its associated plastic deformation mechanisms. In this work, we firstly used a high-throughput GB generation method to construct multiple GB structure for a given misorientation angle, and screen out the ground-state and metastable GB structures according to the energy principle. Six typical symmetrically tilted GBs were investigated, including Σ5(210), Σ17(410) and Σ17(530) GBs around <001> tilt axis, and Σ9(221), Σ11(332), Σ17(223) GBs around <110> axis. Then, molecular dynamics simulations were carried out to perform uniaxial tensile tests on the six GBs and their corresponding metastable GBs at different temperatures. The results show that the tensile strength of <001> metastable GBs differs slightly from the ground-state GB at various temperatures, but for <110> GBs, the strength of most metastable GBs is significantly stronger or weaker compared to that of ground-state GB at 10 K. An increase in temperature reduced this difference in tensile strength of <110> GBs. According to atomic analysis of the GB structural characteristics, it was found that stress and temperature-induced GB structural transition, GB strain localization, and the prevention of dislocation nucleation or propagation from the dissociated structure are the main causes of the differences in tensile responses between the ground-state and metastable GBs.

Modelling of closed-cell aluminum foam using Weaire–Phelan unit cells

AbstractDesign and testing of real materials is a costly process and usually requires some specific equipment. To alleviate this task numerical methods can be leveraged. In this work we show possible modelling technique for closed-cell material structure using Weaire–Phelan unit cells. As an example existing aluminum structures were used and modelled parametrically, allowing to establish different geometrical models for different applications. Numerical simulations for compression was also done on the developed models to reveal the material response. The influence on the cell wall thickness and the friction between the material and the compression plate was investigated. It was found that the friction coefficient has no significant effect on the material response, except in the case where bonded connection was assumed. It was also demonstrated that material response and the porosity controlled by cell wall thickness have an approximately linear relationship with each other. This method proved to be a flexible and alternative solution of real laboratory tests and targeted to reduce costs of material design.

A non-melting additive approach to structural repair of aluminum aircraft fastener holes

The damage to fastener holes in aerospace aluminum structures presents significant challenges for aircraft durability, and conventional bushing methods for repairing oversized holes often fall short due to the lack of metallurgical bonding and limited edge distance availability. This study investigates additive friction stir deposition, a non-melting additive process, as a viable alternative for the structural repair of aerospace fastener holes. The repair process, demonstrated on AA7050 (Al-Zn-Mg-Cu-Zr) hole structures, involves filling oversized holes with new material and machining to restore the original hole size. The repaired hole coupons are defect-free and exhibit good fatigue performance under fully reversed tension-compression loading (R = -1). At a nominal stress amplitude of 123.5 MPa, the average number of cycles to failure is 12,666 for unrepaired baseline coupons and 17,372 for effectively repaired coupons. Restoring complex geometries without compromising fatigue performance has been difficult in aerospace applications; this study marks the first demonstration of additive repair that consistently outperforms the unrepaired baseline coupons. Notably, the result is achieved through a low-energy, cost-effective solution without the need for post-repair heat treatment. Except for a few outliers, the post-repair fatigue performance generally remains inferior to that of undamaged, pristine coupons, likely due to precipitate evolution in AA7050 caused by the thermomechanical processing nature of additive friction stir deposition. This evolution weakens the repair region and the adjacent base material, leading to faster crack initiation and growth compared to the properly aged base material, AA7050-T7451.

Heteronuclear Fe-Mn Cyclopentadienyl Complexes Supported on Boehmite. Thermochemistry and Thermodynamics of their Decomposition

Boehmite samples with compounds of the composition (C5H5)2FeMnX2(μ-CO)n, where X=Cl, Br and n=1.2, precipitated at room temperature from tetrahydrofuran solutions and then heated in an air flow up to 873 K were obtained and characterized using X-ray diffractometry, infrared Fourier spectroscopy, electron magnetic resonance and temperature-programmed desorption methods. It was shown that the thermal decomposition of these compounds applied to the boehmite samples in the range from room temperature to 873 K occurs stepwise and consists of at least two stages. The first stage of thermal decomposition occurs in the range of 453–753 K, and the second – in the range of 813–843 K. The XRD data show that when calcining at 873 K the boehmite samples with the applied compounds of the above composition and containing these compounds less than 10 wt.%, the diffraction patterns show only reflections characteristic of poorly crystallized aluminum oxide. However, the electron paramagnetic resonance (EPR) spectra of these samples clearly show intense signals characteristic of superpara/ferromagnetic particles of iron and manganese oxides, as well as EPR signals from isolated Fe3+ substituting Al3+ ions in the aluminum oxide structure. EPR spectra most of the iron and manganese is stabilized on the surface of poorly crystallized aluminum oxide in the form of nanostructured iron and manganese oxides.