Al Alloy Research Articles

Fatigue strength of additively manufactured hot-dip galvanized steel coated with a Zn–5Al alloy

Fatigue strength of additively manufactured hot-dip galvanized steel coated with a Zn–5Al alloy

Passive thermal management of CO2 Methanation using phase change material with high thermal conductivity

CO2 methanation is a promising technology for fuel decarbonization. Since methanation is an exothermic reaction, thermal management of the reactor is an important issue. This study investigated the effect of applying metallic phase change material(PCM) for reactor thermal management. In this study, Zn-30 %Al alloy(melting point: 429–509 °C)-based PCM composites were mixed with catalysts in a bench scale reactor, then steady-state and transient methanation were examined. The results at steady state indicated peak temperature was reduced from 464 °C to 411 °C compared to conventional single-catalyst condition. This corresponded to 38 % reduction in the temperature difference between peak and base temperature. Furthermore, temperature distribution in the whole reactor was homogenized, achieving a dispersion of the local thermal stress. This was due to high thermal conductivity of metallic PCM. Then, transient thermal management of PCM was evaluated. Periods for temperature increase between 430 and 450 °C, including PCM melting point, was prolonged 45 min compared to the condition without PCM. This resulted 71 % suppression of exothermic speed. This was due to complex effects of latent heat and high thermal conductivity of metallic PCM, offering thermal buffer in case of catalyst thermal runaway. These results showed the introduction of metallic PCM into methanation reactor provides novel thermal management.

Study on the dissolving performance of the Mg-(5, 8, 10wt.%)Sn-1.5wt.%Al alloys

Abstract A metallographic microscope and a scanning microscope were used to observe the extruded and corroded microstructure of the Mg-(5, 8, 10wt.%)Sn-1.5wt.%Al alloys. An electrochemical workstation was used to test the electrochemical performance of these samples. It shows that the Mg-Sn-Al alloys have good plasticity and dissolving properties after extrusion. Among them, the Mg-8wt.%Sn-1.5 wt.%Al alloy has the best plasticity, which is 22.5%. At the same time, it has the best-dissolving properties, with a double-layer capacitance in a solution of 9.448*10−6 F·cm−2. The dissolution process in the 3% kcl solution is a uniform intergranular corrosion.

Interface optimization design and bonding mechanism of friction rolling additive manufactured aluminum/steel dissimilar metal

The aluminum/steel dissimilar structure is a cornerstone for lightweight components and equipment. Yet, traditional fusion welding methods' high heat input frequently gives rise to detrimental defects such as porosity, cracks, and excessively thick intermetallic compound layers (IMCLs) at the interface. To overcome these challenges, this paper innovatively combines low heat input solid-state friction rolling additive manufacturing (FRAM) and strategic interface design to achieve reliable bonding between these dissimilar metals. Our investigation found that conventional FRAM (C-FRAM), hindered by inadequate heat input, struggled to facilitate continuous atomic migration, leading to incomplete joint formation. However, the introduction of arc-assisted FRAM (Aa-FRAM) significantly increased aluminum/steel mixing, fostering interdiffusion of interface atoms under high temperature and pressure conditions. This resulted in the formation of uniform 2.3 μm IMCLs composed of Fe7Al11, Fe4Al13, and FeAl6, and the nanoscale amorphous layer was found between IMCLs and steel. The metallurgical bonding was successfully established at the Aa-FRAM interface. Moreover, by using arc/micro-hole assisted FRAM (AHa-FRAM), which machined an array of micro-holes on the steel surface, we further optimized the aluminum-steel interface bonding quality. The plasticized aluminum alloy (Al alloy) seamlessly flowed into these micro-holes, creating a robust “self-riveting” structure that bolstered mechanical interlocking at the interface. Consequently, we achieved a high-strength joint with an exceptional ultimate tensile strength (UTS) of 167.2 MPa. In addition, the crystallographic analysis showed that the grain size was significantly refined by using the two auxiliary methods, which played a fine grain strengthening role on the interface. This paper innovatively improves the interface bonding between Al alloy and steel through the combination of solid-state FRAM and interface design, thereby opening up a new pathway for the manufacture of aluminum-steel dissimilar structural components.

Investigation of the Al alloy armor materials: A review

Abstract Al alloys have garnered profound scholarly interest for their utilization in armored vehicles and an array of military components, owing to their noteworthy properties which encompass high specific strength, exceptional fracture toughness, unparalleled corrosion resistance, and remarkable ballistic characteristics. Additionally, their exceptional formability coupled with economic feasibility enhances the prospects for large-scale production and deployment, thereby positioning them as a highly preferred material option. The ballistic impact mechanism in Al alloys is an intricate mechanical process, intricately intertwined with the target material’s strength, hardness, ductility, density, toughness, and thickness, as well as the projectile’s characteristics. Currently, a range of lightweight Al alloy armor materials have been engineered to possess superior strength and ductility, rendering them ideally suited for a diverse array of ballistic impact applications. This study aims to consolidate current research findings on Al alloy armor materials, with a keen focus on three pivotal dimensions: ballistic resilience, stress corrosion cracking resistance, and weldability. By integrating insights from diverse research endeavors, we endeavor to deepen our comprehension of these key properties, ultimately laying a solid theoretical and experimental groundwork for the progression of Al alloy armor materials.

Investigation of Microstructures and Mechanical Properties of Al2024/6061/7075-Graphene Composites

This work aimed to compare the mechanical properties and microstructures of Al2024-graphene, Al6061-graphene, and Al7075-graphene composites produced via the induction hot pressing and powder metallurgy method. The influences of graphene content (0.15-0.45wt.%), heat treatment (sintering and induction hot-pressing), and matrix material (Al2024, Al6061, and Al7075) on the mechanical strength and microstructure of specimens were studied. Compared to Al2024, Al6061 and Al7075 alloys, the compressive strength of Al2024-0.15graphene, Al6061-0.15graphene and Al7075-0.15graphene composites increased by 33.74%, 24.9% and 32%, respectively. The highest compressive strength (506±5 MPa), hardness (164±1.5 HV), and apparent density (2.65 g/cm3) were achieved in sintered and induction heat-treated Al7075-0.15%graphene composite. As a result, it was determined that graphene is an effective reinforcement element. It has been determined that induction hot-pressing improves the mechanical strength of composite materials.

Achieving springback-free age forming via dislocation-enhanced stress relaxation in Al alloy

Obtaining zero springback and good post-form performance simultaneously is an ultimate pursuit in metal sheet forming. The stress-relaxation ageing (SRA) behavior and mechanical properties of a commercial 2219 aluminum alloy largely pre-deformed (LPD) by 80% have been systematically investigated. The stress relaxation ratio of the LPD alloy reaches approximately 94% regardless of the initial stress (50-350 MPa) after ageing for 12 h at 140°C. This relaxation ratio is about 2.9 and 1.8 times that in the T4 tempered alloy (27.6% under 50 MPa and 31.5% under 150 MPa) and T3 tempered alloy (37.6% under 50 MPa and 51.2% under 150 MPa), respectively. The microstructures, comprised of GP zones/θ' precipitates plus dislocation tangles, and tensile properties in the stress-relaxation-aged LPD alloys remain basically invariant with different initial stresses, as is vital importance for property consistency at different locations of the formed part. Under the same SRA condition, the LPD alloy has an increase of 150-230 MPa in yield strength relative to T3/T4 tempered alloy and obtains a uniform elongation of about 8%. A simple dislocation-based constitutive model accurately describing stress relaxation enhanced by the high dislocation density is established and embedded in the finite element package through a user subroutine. Simulations and experimental verifications show the LPD alloy sheet parts exhibit a nearly zero springback (< 5%) after unloading in contrast to the springback larger than 65% in the T3/T4 alloy sheet parts under the same condition. Our findings demonstrate the high-dislocation-density-enhanced SRA response enables a high-performance springback-free age forming of Al alloy sheet.

Investigating how Cu content and oxidation time affect the hardness and corrosion resistance of MAO coatings on Al alloy

Investigating how Cu content and oxidation time affect the hardness and corrosion resistance of MAO coatings on Al alloy

Fabrication and characterization of Al alloy composites reinforced with nanocrystalline Al4CrFeMnTi0.25 high-entropy alloy particles via double ultrasonic stir casting for aerospace applications

The aim of the present work is to fabricate the Al alloy-based composites by using a new class of High Entropy Alloy (HEA) reinforcement particles for aerospace applications, addressing the limitations associated with traditional ceramic reinforcement particles. Therefore, the present work is to fabricate an Al-7150 alloy-based composite by incorporating a novel nanocrystalline Al4CrFeMnTi0.25 HEA (NCHEA) reinforcing particle (0.5, 1, 1.5 and 2 wt%) through a double ultrasonic two-step stir casting technique. The relative density decreases with the addition of NCHEA particles in the mixture, however, the porosity remains below 5 % due to double ultrasonication. The grain size was significantly refined with the addition of NCHEA particles. The AA7150-HEA composite exhibits a “stone in mud” structure in which the HEA particles (stone) are embedded in an aluminum matrix (mud) due to the high density of NCHEA reinforcement. The AA7150–1.5 wt% HEA composite exhibited a small average crystallite size of 27.03 nm and a maximum dislocation density of 2.67 nm-2 analysed by X-Ray Diffraction (XRD) analysis. The AA7150–1.5 wt% HEA alloy achieved a maximum Vickers microhardness of 214.49 HV and an ultimate tensile strength of 218.37 MPa, which were 37 % and 27.5 % higher, respectively, compared to the base Al-7150 alloys. Failure usually occurs at the interface where the alloy is bonded to the ceramic reinforcement, however, in the HEA-reinforced composite, this fall-off action does not occur as observed by fractographic analysis. Nonetheless, Al7150–2wt% HEA-composites have many cracks on the fractured surface due to the agglomeration of NCHEA particles in composite. The NCHEA reinforcement particles can be incorporated into the Al7150 matrix as an alternative to ceramic reinforcements, enabling enhanced strength improvement.

Effect of Stable and Transient Cavitation on Ultrasonic Degassing of Al Alloy

Cavitation is a critical phenomenon for improving melt quality in casting processes by reducing hydrogen porosity, and it can be classified into two major types based on bubble dynamics, stable and transient cavitation. In this study, the relationship between stable and transient cavitation and the degassing efficiency of A356 alloy was evaluated. Cavitation intensity was quantified based on the Karman vortices method, and the measured cavitation intensities were processed through FFT transformation to analyze the acoustic spectra. The line spectrum and continuous spectrum were characterized separately to quantify stable and transient cavitation in distilled water. Negligible change in stable cavitation was observed, while transient cavitation increased with amplitude. On the other hand, both stable and transient cavitation increased proportionally with frequency. By employing the characterized cavitation indices, the effects of stable and transient cavitation on ultrasonic degassing of A356 were assessed. It was confirmed that transient cavitation was the dominant factor in the degassing before the degassing efficiency reached a steady state. This study clearly demonstrates that optimizing frequency to enhance transient cavitation is a more effective approach for increasing intensity and, consequently, improving degassing efficiency.

Effect of integrity degradation caused by fatigue damage on impact failure for automotive FSSW Al alloy joints

Effect of integrity degradation caused by fatigue damage on impact failure for automotive FSSW Al alloy joints

Experimental and theoretical study on the hydrogen evolution inhibition performance of Herba speranskia tuberculata extract on Al alloy waste dust

Experimental and theoretical study on the hydrogen evolution inhibition performance of Herba speranskia tuberculata extract on Al alloy waste dust

Long-term corrosion resistance of superhydrophobic Ce-Co-Al LDH composite coatings prepared on the surface of Al alloy

Long-term corrosion resistance of superhydrophobic Ce-Co-Al LDH composite coatings prepared on the surface of Al alloy

Numerical Simulation Analysis on Anti-Penetration Characteristics of Al/UHMWPE Composite Plates Against Tungsten Alloy Fragment

Abstract With the rapid growing demand for armor protection systems that prioritize reduced weight, Al/UHMWPE composite plates have become a promising option in armor protection field. In this work, the finite element model of the Al/UHMWPE composite plates against tungsten alloy fragment was established firstly to investigate the influence of the interfacial strength on the ballistic performance. In addition, both the failure mechanisms and energy-absorbing performance of AI/UHMWPE composite plates were also systematically explored. Numerical simulation results indicate that lower interfacial strength can more accurately simulate the phenomenon of sub-laminates separation under high-speed penetration conditions. The failure mechanisms of Al/UHMWPE composite plates involve sequential processes including deformation of the Al alloy plate, tensile deformation of the UHMWPE laminated plate, fracture of the sub-laminate, and finally, delamination of the UHMWPE laminated plate. Furthermore, the specific energy absorption (SEA) was utilized to quantify the ballistic performance between Al alloy plate and UHMWPE plate, demonstrating that UHMWPE plate significantly dominates, with a capability of 16.4 J/(kg/m2), accounting for 53.4% of total SEA.

Study on the Microstructure and Properties of Al Alloy/Steel CMT Welding–Brazing Joints Under Different Pulse Magnetic Field Intensities

Butt welding experiments on 6061 Al alloy and Q235B steel of 2 mm thickness were conducted using an ER4047F flux-cored wire as the filler metal, after adding a pulsed magnetic field into the process of cold metal transfer (CMT) welding. The effect of the pulsed magnetic field intensity on the macro morphology, microstructure, tensile strength and corrosion resistance of the welding–brazing joint was analyzed. The results showed that when the pulsed magnetic field intensity increased from 0 to 60 mT, the wettability and spreadability of the liquid metal were improved. As a result, the appearance of the Al alloy/steel joint was nice. However, when the pulsed magnetic field intensity was 80 mT, the stability of the arc and the forming quality of the joint decreased, which resulted in a deterioration in the appearance of the joint. A pulsed magnetic field with different intensities did not alter the microstructure of the joint. All of the joint was composed of θ-Fe2(Al,Si)5 and τ5-Al7.2Fe1.8Si at the interface and Al-Si eutectic phase and α-Al solid solution at the weld seam zone. Actually, with the pulsed magnetic field intensity increasing from 0 mT to 60 mT, the IMC thickness in the interfacial layer gradually reduced under the action of electromagnetic stirring. Also, the grain in the weld seam was refined, and elements were distributed uniformly. But when the pulsed magnetic field intensity was 80 mT, the grain in the weld seam began to coarsen, and the intermetallic compound (IMC) thickness was too small, which was unfavorable for the metallurgical bonding of Al alloy and steel. Therefore, with the increase in pulsed magnetic field intensity, the tensile strength of the joints first increased and then decreased, and it reached its maximum of 187.7 MPa with a pulsed magnetic field intensity of 60 mT. Similarly, the corrosion resistance of the joint first increased and then decreased, and it was best when the pulse magnetic field intensity was 60 mT. The Nyquist plot and Bode plot confirmed this result. The addition of a pulsed magnetic field caused less fluctuation in the anode current density, resulting in less localized corrosion of the joint using the scanning vibrating electrode technique (SVET). The XPS analysis showed the Al-Fe-Si compounds replacing the Fe-Al compounds in the joint was the main reason for improving its corrosion resistance under the action of a pulsed magnetic field.

Current waveform effects on AC-CMT arc welding of 7075 Al alloy with addition of ER7075 wire

Current waveform effects on AC-CMT arc welding of 7075 Al alloy with addition of ER7075 wire

Strong and thermally stable nanocrystalline Cu–Al alloy via Al segregation

Strong and thermally stable nanocrystalline Cu–Al alloy via Al segregation

Hot Deformation and Dynamic Recrystallization of 7075 Al Alloy in the Extruded State

Hot Deformation and Dynamic Recrystallization of 7075 Al Alloy in the Extruded State

Fatigue life of friction stir spot welds between Z91 magnesium alloy and ENAW7075-T651 aluminum alloy

Abstract Magnesium (Mg) and aluminum (Al) alloys are considered to be among the lightest structural metals. Using these materials in a design can considerably decrease weight, which brings many benefits like reducing fuel consumption and increasing the performance of an aircraft or a ground vehicle. However, these alloys are too difficult to be joined via fusion welding techniques. In this context, welding AZ91 Mg alloy to ENAW7075-T651 Al alloy by the solid-state welding method of friction stir spot welding was investigated comprehensively. These alloys were welded by utilizing a tool with a triangle pin and various tool rotational speeds (1,000, 1,400, and 1,800 rpm) and welding times (3 and 6 s). Macro and microstructure of the welds and their hardness, tensile strength, and tension-compression fatigue life were determined. Generally, an improvement in the mechanical properties of the weld was observed by increasing the welding time due to the expansion of the joining area. The welding with the best mechanical properties was obtained at 1,400 rpm, and the worst at 1,800 rpm. All the welds failed from the weld area during the tensile and fatigue tests and exhibited a brittle fracture mode due to the formation of intermetallic compounds in the welds.

Microstructure observation of T-phase in Al-Zn-Mg alloy with low Zn/Mg ratio

For the first time, this study clarifies the interface of the T’’, T’, and T-phase in Al-Zn-Mg alloy with a low Zn/Mg ratio and evaluates the shape of the precipitate morphology according to different zone directions of the Al matrix. The orientation relationship, shape, misfit, and interfacial conditions between the T’’, T’, and T-phase and the Al matrix were investigated using high-resolution transmission electron microscopy (HR-TEM). We differentiated the T’’ (a=1.387 nm), T’ (a=1.422 nm), and T (a=1.456 nm) phase by calculating the lattice parameters in HR-TEM images. We also identified the T’’, T’, and T-phase by diffraction patterns along the <100>, <110>, <111>, and <112> zone directions of the Al matrix. Additionally, we introduce the different orientation relationships of the T-phase with the Al matrix, The [11¯0] zone direction of the Al is parallel to the [3¯20] direction of the T-phase, and the plane of (11¯1) of the Al is parallel to the plane of (112̅) of the T-phase. Among Al alloys, the 7xxx series is known for its superior strength due to the co-precipitation of the η and T-phase. While previous research has extensively examined the precipitation sequence, composition, atomic structure, and phase transformation mechanisms of the η-phase, the T-phase has received less attention. Our observations provide insight into the behavior of T-phase crystals, which is crucial for understanding the microstructural evolution of Al-Zn-Mg alloys and for designing materials with desired properties.