Duralumin Research Articles

Microstructure Refinement or Increased Copper Solubility: Factors That Contribute to the Pitting Corrosion Tendency in Aluminum–Copper Alloys

Aluminum–copper alloys are commonly used in the aerospace industry due to their low density and high strength. Pitting corrosion is the major problem of Al-Cu alloys due to the presence of largely separated electrochemical potential difference phases. Microstructure refinement and phase homogenization of the alloys are believed to be the factors that contribute to decreasing the galvanic coupling between phases, hence decreasing the pitting tendency. In this work, we investigate whether microstructure refinement is the only factor that contributes to pitting or whether some other factors are involved in the pitting tendency. The investigation was conducted on two frequently used aerospace aluminum–copper alloys, Al-2024 T3 and Al-2014 T6. The surface refinement was conducted by laser surface melting, and microstructure characterization was conducted by scanning electron microscopy with an energy-dispersive X-ray analysis. Phase identification before and after the laser surface melting was conducted by X-ray diffraction, while pitting tendency was measured by a polarization test in 1 molar sodium chloride solution. These experimental results revealed that the enrichment of copper in the α-matrix phase was the major contributing factor in pitting as compared to the largely believed microstructural phase refinement.

Features of Alloying and Heat Treatment of High-Strength Casting Aluminium–Copper Alloys

Features of Alloying and Heat Treatment of High-Strength Casting Aluminium–Copper Alloys

Effects of Copper Content and Thermo-Mechanical Treatment on Microstructure and Mechanical Properties of AlMgSi(Cu) Alloys

This study presents the results of research on the influence of different contents of copper in aluminium alloys based on the 6xxx series on mechanical and structural properties. The investigation started with the alloying, and casting four billet variants with different copper content—0.8% Cu; 2B—1% Cu; 3A—1.2% Cu; and 3B—1.4% Cu. The prepared materials were homogenised and extruded on a 500T horizontal press with two different process temperatures and ram speeds ranging from 1 mm/s to 9 mm/s. After heat treating to the T6 and T5 tempers, their mechanical properties were tested. On this basis, the two most promising alloys 2A and 3B were selected and subjected to further tests. After extrusion and heat treatment of the profiles (to F, T1, T2, T5, and T5510), their mechanical properties were determined to select the preferred process parameters. Finally, a structural test based on crystallographic orientation based on the EBSD technique and TEM observations allowed for the characterisation of grain size, dispersoids, and phase analysis. Bright-field (BF) analysis allowed us to compare the deformed areas for T1, T5, and T5510 temperatures. The results showed significant growth in the mechanical properties of all the subjected alloys, and the best properties were shown for a Cu content of 1.4% with a tensile strength of 460 MPa and an elongation of 16% (T5510 tempering). The structural test showed an average grain size of 18 µm to 23 µm and solid solution decomposition differences for different heat-treating parameters.

Evaluation of Structural Transition Joints Cu-Al-AlMg3 Used in Galvanizer Hangers

The paper deals with the evaluation of the quality of Cu-Al-AlMg3 structural transition joints (STJ) made by explosion welding proposed for the renovation of galvanizer hangers. The three-layer joint consisted of electrolytic copper with a thickness of 25 mm, 2 mm of aluminium represented by the AW1050 alloy, and 25 mm of the EN AW 575 aluminium alloy. Light microscopy analysis confirmed the wavy pattern of both interfaces of the welded joint and significant plastic deformation in close proximity to the waves. Microhardness measurement revealed a partial strain hardening of the AW5754 copper-aluminium alloy near the interface and a significant increase in microhardness in the vortex zone of waves, reaching a value of up to 863 HV 0.025. Microcracks were also observed in these places. The intermetallic phase Al2Cu was identified in the vortex zones by XRD analysis. As a continuous layer of intermetallic phase was not observed in the interface of the welded joint, it is possible to consider the used welding parameters as appropriate. A semi-quantitative EDX analysis revealed a diversity of chemical composition in the vortex zones, which does not correspond to the phase composition based on the equilibrium binary Al-Cu diagram due to non-equilibrium conditions in the formation of the welded joint interface. The bond strength of three-layer welded joint evaluated by the strength test ranged from 151 to 171 MPa, which represented approximately a two-fold increase in comparison to the ultimate tensile strength of alloy AW1050, while the failure occurred in all samples at the AW1050-AW5754 alloy interface.

Microstructure and radiation shielding capabilities of Al-Cu and Al-Mn alloys

In this study, the microstructure and elemental analysis of aluminum-copper alloy type-2024, Al-2024, and aluminum-manganese alloy type-3003, Al-3003, have been investigated by using a scanning electron microscope (SEM) equipped with Energy dispersive spectroscopy (EDS) detector. Experimental and theoretical radiation shielding studies were performed to assess the radiation shielding capabilities of the studied alloys. Considering the radiation shielding theoretical assessment, some reliable software tools were used, such as Phy-X/PSD, MCNP5, NXCom, and MRCsC. The microstructural observations and results have shown the presence of second phases rich with the main alloying elements in both alloys. Considering Al-2024 alloy, coarse second-phase particles, having a size range of 8–15 μm, were found aligning in lines parallel to the rolling direction, whereas smaller ones, having a size range of 2–8 μm, were found decorated the grain boundaries. Also, dark holes represent the pull-out large particles separated during preparation indicated poor adhesion with the main matrix that could be a result of losing particle coherency with the matrix where the misorientation in-between the atomic planes increase. However, better adhesion of the second-phase particles with the matrix, which were found possessing smaller particle size, have been observed in the Al-3003 alloy indicating good coherency and better manufacturing process for the non-heat-treatable alloy. The second-phase particles in case of Al-2024 alloy were found containing significant content of high-Z elements like Cu with greater volume fraction equals 7.5%. On the other side, Al-3003 alloy has possessed second-phase particles which lack of high-Z elements with only volume fraction equals 3.5%. All the former besides the higher density and content of high-Z elements like copper in Al-2024 alloy in compare to Al-3003 alloy and pure aluminum, led to relatively better radiation shielding capabilities against energetic photons, the highest in the low energy band and decreases with the increase of the photon energy, and slight superiority in the case of fast neutrons with only 3%inc. over pure aluminum. For instance, the radiation protection efficiency (RPE) values dropped from about; 23.2, 21.6, and 20.8% at 0.100 MeV to only 5.7, 5.9, and 5.6% at Eγ = 2 MeV, for; Al-2024, Al-3003, and Al-Pure, respectively."Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.""confirmed"

Tribological and corrosion characteristics of aluminium–copper alloys reinforced with alumina nickel aluminide cermet powder

Aluminium–Copper (Al-10Cu) alloys are widely used for structural components in the aviation sector. This study focuses on the synthesis and characterisation of Al-10Cu alloy reinforced with Al2O3-30(Ni-20Al) cermet particles to evaluate their microstructural, mechanical, tribological and corrosion properties. The Al-10Cu alloy was cast with varying percentages of cermet (2% and 4%) using a controlled casting process. Comprehensive microstructural analyses, including optical microscopy, SEM and EBSD, were performed to assess the grain structure and cermet distribution. The mechanical properties were evaluated through Vickers microhardness and tensile testing, while tribological performance was assessed using a Pin-on-Disc tribometer. Corrosion resistance was investigated through exfoliation and immersion corrosion tests. The results indicated significant improvements in microhardness and wear resistance with the addition of cermet particles, while the tensile strength showed a complex interplay between ductility and brittleness. Corrosion tests revealed enhanced resistance in cermet-reinforced specimens. This study demonstrates the potential of Al2O3-30(Ni-20Al) cermet as an effective reinforcement for aluminium alloys to achieve superior performance in structural applications.

Effect of manufacturing new U-shaped electrode on die sinking EDM process performance

Traditional electrical discharge machining (EDM) electrodes have several limitations such as long machining time, low material removal rate MRR, hazard emissions and high energy consumption. To overcome these limitations, new electrodes (plane and frame U-shaped) were manufactured considering the electrode manufacturing classifications, such as electrode flushing mechanism, electrode cross-sectional area and electrode bottom machining area. Experiments were performed on a die-sinking EDM machine using copper electrodes and aluminum alloy workpieces. The results were compared with those obtained using the conventional electrode. The newly manufactured electrodes significantly improved the EDM process performance, reducing the machining time by more than 50%, which implies a higher MRR. The reduced machining time also led to lower costs, emissions and energy consumption for efficient EDM processes. Additionally, surface roughness measurements were performed to compare the surface quality of the machined areas using different pulse-code generator systems and electrodes. The results showed an improvement in the machined surface quality when using the new electrodes in comparison with the conventional electrode when using a roughing pulse code generator system.

Analysis of quadrupolar frequencies of the spherical gravitational wave detector by finite element modeling: A study case

The Schenberg detector is a spherical resonant antenna gravitational wave detector with a solid sphere with a diameter of 65 cm and a weight of approximately 1.15 metric tons. It is made of a copper–aluminum alloy with 94% Cu and 6% Al. This work aims to verify the natural frequencies of the Schenberg detector structure. The authors used the finite element method to calculate the quadrupole frequency band and compare it with the value measured in tests during the construction of the antenna at University of Sao Paulo, which was 67.3 Hz. In the modal simulation with the homogenous material, the frequency band of the quadrupole modes was around 35 Hz. Many trials to improve this result were made with no significant improvement. The improvement came when the sphere was considered not homogenous, as to the cooling process of the sphere casting, the alloy that cooled faster (close to the surface sides and in the bottom) can reach a hardness 20% higher than the material that cooled slower (in the center and on the top). Including these characteristics, the band value obtained was close to the one measured during the construction of the antenna, a value of 63.2 Hz was obtained.

Influence of Sodium Chloride and Potassium Fluoride on Electrochemical Properties of Aluminum Copper Interdigital Structures

This paper evaluates the electrochemical properties of aluminum (0.5 w%) copper alloy metallized test chip surfaces with interdigital structures and distances between 3 and 20 μm, regarding sodium chloride and potassium fluoride contamination in the range of 1011–1016 ions per cm2 at high humidity (85%) and high temperature (85 °C). These accelerated tests result in leakage currents and impedance values which show a significant change above a contamination limit value of 1014 ions per cm2 for both salts i.e., the leakage current starts to increase well above a few pico amperes, and the impedance decreases significantly. This contamination level can be seen as a turning point, after which devices can undergo for example signal shifts or corroded metal tracks over lifetime. But not only the start point of an increase in leakage current decides about the harmfulness of the contamination, other important influences are deliquescence and how high the leakage current gets at its maximum. Therefore, even with the same starting point, the risk evaluation is not the same for sodium chloride and potassium fluoride.

Effect of welding gap on electromagnetic pulse welding of a copper-aluminum alloy joint

ABSTRACT Electromagnetic pulse welding (EMPW) is commonly used for welding copper and aluminum alloy. The welding gap is important in the EMPW process. The research focused on the effect of welding gap on the welding process and the mechanical property of joints. During the EMPW experiments, the deformation, collision, and metal jet were recorded with a high-speed camera. The joint mechanical property was tested. SEM and EDS were employed to examine the bonding interface. Results indicated that the welding gap length did not significantly influence the aluminum alloy plate motion behavior when it was long enough. With the welding gap width increasing, the collision velocity initially increased and subsequently decreased, and the angle between the two plates when they first collided increased continuously. The intensity and duration of the metal jet and the joint mechanical properties also increased first and then decreased. The welding marks widened first and then narrowed.

Electron Beam Welding of Copper and Aluminum Alloy with Magnetron Sputtered Titanium Filler

In this work, the results from the electron beam welding of copper and Al6082T6 aluminum alloy with a titanium filler are presented. The influence of the filler on the structure and mechanical properties of the welded joint is studied in comparison with one without filler. The X-ray diffraction (XRD) method was used to obtain the phase composition of the welded joints. Scanning electron microscopy (SEM) was used for the study of the microstructure of the welds. Energy-dispersive X-ray spectroscopy (EDX) was applied to investigate the chemical composition. The mechanical properties were studied by means of microhardness measurements and tensile tests. A three-phase structure was obtained in the fusion zone consisting of an aluminum matrix, an intermetallic compound CuAl2, and pure copper. The application of Ti filler significantly decreased the amount of molten copper introduced in the molten pool and the number of intermetallic compounds (IMCs). This improved the strength of the joint; however, some quantity of IMCs was still present in the zone of fusion (FZ), which reflected the microhardness of the samples. The application of a titanium filler resulted in refining the electron beam weld’s structure. The finer structure and the reduced amount of the brittle intermetallic phases has led to an increase in the strength of the joint.

Molecular Dynamics Simulation Study of Aluminum-Copper Alloys' Anisotropy under Different Loading Conditions and Different Crystal Orientations.

The commonly used aluminum-copper alloys in industry are mainly rolled plates and extruded or drawn bars. The aluminum-copper alloys' anisotropy generated in the manufacturing process is unfavorable for subsequent applications. Its underlying mechanism shall be interpreted from a microscopic perspective. This paper conducted the loading simulation on Al-4%Cu alloy crystals at the microscopic scale with molecular dynamics technology. Uniaxial tension and compression loading were carried out along three orientations: X-<1¯12>, Y-<11¯1>, and Z-<110>. It analyzes the micro-mechanisms that affect the performance changes of aluminum-copper alloys through the combination of stress-strain curves and different organizational analysis approaches. As shown by the results, the elastic modulus and yield strength are the highest under tension along the <11¯1> direction. Such is the case for the reasons below: The close-packed plane of atoms ensures large atomic binding forces. In addition, the Stair-rod dislocation forms a Lomer-Cottrell dislocation lock, which has a strengthening effect on the material. The elastic modulus and yield strength are the smallest under tension along the <110> direction, and the periodic arrangement of HCP atom stacking faults serves as the main deformation mechanism. This is because the atomic arrangement on the <110> plane is relatively loose, which tends to cause atomic misalignment. When compressed in different directions, the plastic deformation mechanism is mainly dominated by dislocations and stacking faults. When compressed along the <110> direction, it has a relatively high dislocation density and the maximum yield strength. That should be attributed to the facts below. As the atomic arrangement of the <110> plane itself was not dense originally, compression loading would cause an increasingly tighter arrangement. In such a case, the stress could only be released through dislocations. This research aims to provide a reference for optimizing the processing technology and preparation methods of aluminum-copper alloy materials.

The influence of aluminum content on thermal properties of copper-aluminum alloys: a first-principles calculation

Abstract Copper-aluminum alloy, also called aluminum bronze, is a type of host material for abradable sealing coatings. The amount of aluminum content obviously affects the properties of the coating. This research uses the density functional theory to calculate the properties of an aluminum bronze with different aluminum content. The copper-aluminum alloy model uses the model of special quasirandom structures (SQS). The elastic constant, melting point, constant pressure specific heat capacity, and thermal expansion coefficient of the copper-aluminum alloys were calculated using the quasi-harmonic approximation (QHA) method. The copper-aluminum alloys with three different nominal components were prepared using vacuum induction melting. The melting point, thermal expansion coefficient, and specific heat capacity of the copper-aluminum alloys were characterized through experiments. The results showed that the melting point of the copper-aluminum alloys decreased with an increase in aluminum content. Additionally, the coefficient of thermal expansion of the copper-aluminum alloy increased with the increase in aluminum content. Furthermore, the specific heat capacity of the copper-aluminum alloy initially increased and then reached a turning point when the β’ phase was generated. The experimental values conform well to the calculated values.

Joining of Copper and Aluminum Alloy A6061 Plates at Edges by High-Speed Sliding with Compression

By using the joined or welded materials of dissimilar metals, the characteristics and performance of products and parts can be improved. The combination of copper and aluminum is difficult to weld. In this study, the impact joining of copper C1100 and aluminum alloy A6061-T6 plates at the edges was investigated to explore the appropriate joining conditions. The plates are joined with newly created surfaces generated by the high-speed compressive deformation with sliding motion. The shape near the interface was a tapered trapezoid with a flat top. The joining length in the plate thickness direction was shorter than the plate thickness, and notches were observed near both plate surfaces. The length became slightly longer by setting a larger top width of the C1100 plate than that of A6061-T6. The joint efficiency increased by approximately 10%. Applying the emery paper finish to the surface of the plate eliminated the non-joining result in multiple experiments. The finishing direction is effective only in the longitudinal direction of the plate. In the tensile test on the dumbbell-type specimen with reduced thickness to eliminate notches, most results showed a fracture at the C1100 portion. The estimated temperature rise of the C1100 is more than about 250 K during the impact deformation. Hence, the strength of the A6061-T6 becomes lower than that of C1100 during the process, and the softened layer of aluminum comes out under pressure, resulting in good joining performance.

Numerical simulation of microstructure and microporosity morphology in directional solidification of aluminum-copper alloys: Effect of copper content and withdrawal rate

Numerical simulation of microstructure and microporosity morphology in directional solidification of aluminum-copper alloys: Effect of copper content and withdrawal rate

Anodizing of AA2024 Aluminum–Copper Alloy in Citric-Sulfuric Acid Solution: Effect of Current Density on Corrosion Resistance

Al–Cu alloys are widely used as a structural material in the manufacture of commercial aircraft due to their high mechanical properties such as hardness, strength, low density, and tolerance to fatigue damage and corrosion. One of the main problems of these Al–Cu alloy systems is their low corrosion resistance. The purpose of this study is to analyze the influence of anodizing parameters on aluminum–copper alloy (AA 2024) using a bath of citric-sulfuric acid with different anodizing current densities on the thickness, microhardness, and corrosion resistance of the anodized layer. Hard anodizing is performed on AA 2024 Al–Cu alloy in mixtures of solutions composed of citric and sulfuric acid at different concentrations for 60 min and using current densities (i) of 0.03, 0.045, and 0.06 A/cm2. Scanning electron microscopy (SEM) was used to analyze the surface morphology and thickness of the anodized layer. The mechanical properties of the hard anodized material are evaluated using the Vickers hardness test. The electrochemical techniques use cyclic potentiodynamic polarization curves (CPPC) according to ASTM-G6 and electrochemical impedance spectroscopy (EIS) according to ASTM-G61 and ASTM-G106, respectively, in the electrolyte of NaCl at 3.5 wt. % as a simulation of the marine atmosphere. The results indicate that corrosion resistance anodizing in citric-sulfuric acid solutions with a current density of 0.06 A/cm2 is the best with a corrosion current density (jcorr) of 1.29 × 10−8 A/cm2. It is possible to produce hard anodizing with citric and sulfuric acid solutions that exhibit mechanical properties and corrosion resistance similar or superior to conventional sulfuric acid anodizing.

"Fabrication of cutting inserts with chromium-molybdenum steel for turning operations using material extrusion technology"

In this study, cutting inserts for turning were produced using metal 3D printing's material extrusion technology. The primary focus was on optimizing cutting parameters. An experimental plan was devised involving rounds of cutting tests based on a design of experiments and analysis of variance. Inserts were manufactured by printing bound metal powder filament, a combination of chromium-molybdenum tool steel with a polymeric binder. After printing, green parts underwent debinding to eliminate the binder, eventually resulting in full metal parts via sintering. These inserts underwent machining tests on aluminum-copper EN AW-2030 alloy specimens. Results indicated that the inserts could function within cutting speeds (Vc) ranging from 40 to 260 m/min, feed rates (f) from 0.05 to 0.25 mm/r, and radial pass depths (ap) from 0.1 to 2.4 mm. Optimal technological conditions were determined as Vc = 160–200 m/min, f = 0.20–0.25 mm/r, and ap = 1.2 mm. Analysis revealed that cutting speed was less significant than feed rate or depth of cut on tool wear. Feed rate minimized wear within the 0.15–0.25 mm/r range, while pass depth proved most influential on wear, with optimal values between 0.8 and 1.2 mm. Surface finish, assessed through mean roughness Ra, showed high dependence on pass depth, improving for low ap values and relatively high Vc values. These findings demonstrate that inserts fabricated via material extrusion can operate within a technological range like commercial inserts, presenting an advanced approach for customizing design and manufacturing while surpassing conventional insert limitations.

Implementation of specifically designed deep neural networks for the prediction and optimization of tensile properties of aluminum-copper alloy

Alloys are engineered materials aimed at enhancing mechanical properties. Extensive research has focused on identifying the optimal metal composition for alloys with superior tensile strength. This study validates the stiffness and strength values of an aluminum-copper alloy through a comparison with a molecular dynamics simulation. Subsequently, 100 data points were obtained from the simulation, and a deep neural network (DNN) with three hidden layers was employed. The DNN was trained, tested, and its structure optimized using the Taguchi design of experiment. The proposed DNN structures successfully predicted the maximum values of the stiffness and strength, which were further verified using molecular dynamics simulation. Notably, the results demonstrated the complete reliability of the Taguchi-designed DNN algorithm in this application.

A computational study of binary eutectic system with convection under volumetric freezing: A Moving Boundary Problem

A reduction in the operating time during the solidification of an eutectic alloy is one of the prime demands in front of the investigators. The classical theory of solidification was not able to offer rapid solidification of an alloy due to not account the structural property of the material. To account convection and external heat sink effect, an external volumetric heat sink is considered and it depends on the distance and time. The thermal conductivity, density, and specific heat of the mushy zone are assumed to be the linear combination of solid and liquid regions properties with a solid fraction distribution. The mathematical model accounts for the solid fraction distribution, which has a linear relationship with the temperature of the mushy zone. The analytical solution of the problem has been determined via similarity transformation. To explore the current study, numerical data of the Copper-Aluminum alloy with 5% Copper is presented. It has been found that with a volumetric heat sink, the rate of solidification becomes faster than usual. Further, the rate of heat removal from the surface accelerates. Convection enhances the rate of freezing of the eutectic alloy. The temperature of the mushy region is going up for the increasing value of the solid fraction in mushy zone, which is lying in [0,1] and when we increase the strength of volumetric heat, then the temperature profile decreases and, the first-interface and second-interface increase gradually in the whole medium. We compared the current result with Tien and Geiger’s result, and it is found in good compliance. It is expected that the current study will improve the fundamental understanding of the solidification of an eutectic alloy and reduce the time for freezing, which is useful to design industrial freezing devices for alloys.

Improving Thermal and Mechanical Properties of CuـAl Based Alloy Used for High-Temperature Applications (A Review) By IJISRT

Despite the increased usage of composite materials, high-strength aluminum alloys maintain significance in airframe construction. Aluminum's attributes of being lightweight, relatively low-cost, heat- treatable, and capable of withstanding high-stress levels contribute to its continued importance. These properties also reduce manufacturing and maintenance costs compared to other high-performance materials. Recent advancements in aluminum aircraft alloys have enabled them to compete effectively with modern composite materials. This study delves into the latest developments, focusing on improving the mechanical properties of aluminum alloys and utilizing high-performance joining techniques. Cu-Al-based alloys represent a new class of functional materials. Due to their unique thermoelastic martensite structure, their exceptional damping performance has garnered attention in materials science and engineering. However, challenges such as elastic anisotropy and larger grain sizes can lead to brittle fractures, impacting the material's mechanical properties. It is widely acknowledged that achieving a finer grain size is pivotal when creating Copper Aluminum alloys with exceptional mechanical attributes and effective damping characteristics. Smaller grain sizes allow for the combined use of fine grain strengthening and interfacial damping, resulting in alloys demonstrating exceptional overall characteristics. This paper presents several standard approaches for preparing Copper Aluminum alloys, subsequently examining research efforts dedicated to enhancing grain size through alloying and heat treatment. Moreover, nanomaterials are being investigated as potential agents for reinforcing Cu–Al-based alloys, leading to substantial improvements in their mechanical characteristics and damping capacities. The study aims to serve as a valuable reference for future research in developing structure-function integrated materials capable of simultaneously offering high strength and high damping characteristics.