Lithium Aluminum Research Articles

Experimental investigation and simulation assessment on fluidity and hot tearing susceptibility of Al-Li-Cu-X alloy: The role of microalloying elements

The meticulous exploration of castability, especially the fluidity and hot tearing susceptibility (HTS), assumes paramount significance in the fabrication of high-quality Al-Li-Cu alloys. In this work, the effect of microalloying elements such as Ti, Mg, Si, Zr, and Sc on the fluidity and HTS of the alloys was systematically investigated, and the significant improvement in fluidity and the reduction in HTS by the addition of these microalloying elements were identified. Comparative analyses with the Al-3Li-1.5Cu alloy reveal a significant increase of up to 45 % in fluidity and a remarkable reduction of up to 83 % in HTS with the addition of these microalloying elements. To unveil the underlying mechanisms, the experimental results were compared with the predictions derived from the CSC criterion, Kou's criterion, and a numerical simulation performed using ProCAST software. The analysis reveals a discrepancy between these predictions and the experimental outcomes, highlighting their limitations in capturing the nuanced effects of minor microalloying elements on fluidity and HTS. Subsequently, a detailed exploration of other influencing factors, including microstructural features, solidification interval, and various thermophysical parameters, was conducted, illuminating the corresponding mechanisms. These findings are expected to provide valuable insights into the fluidity and HTS of Al-Li-Cu-X alloys, thereby contributing to the application and advancement of cast AlLi alloys.

Study on the Effect of Dry and Wet Cycle Time Ratio on the Corrosion Behavior of 2198 Aluminum–Lithium Alloy

ABSTRACTThe corrosion of 2198 aluminum–lithium alloy in a marine atmospheric environment was simulated using a wet–dry alternating experimental setup. Weight‐loss measurement methods, electrochemical impedance spectroscopy (EIS), scanning electron microscopy/energy‐dispersive spectroscopy (SEM/EDS), macroscopic morphology testing, three‐dimensional morphology testing, and X‐ray photoelectron spectroscopy (XPS) were used to study the wet–dry alternating corrosion behaviors and mechanisms of 2198 aluminum–lithium alloys under simulated marine atmospheric environment. The results indicate that corrosion weight loss increases with decreasing wet‐to‐dry ratios, accompanied by an increase in the corrosion rate. Various data suggest that the primary corrosion products are composed of Al2O3, AlO(OH), and AlCl3. The reduction in the wet‐to‐dry ratio leads to the enrichment of Cl⁻ within the corrosion products, extending the contact time between the substrate and the medium, thereby intensifying the hydrolysis of Al³⁺. This exacerbates the dissolution at pitting sites, which in turn erodes and breaks down the corrosion product film, accelerating the overall corrosion process.

Mechanical and microstructural characteristics of Al-Li2099-graphene MMCs for aerospace applications

ABSTRACT Aluminium-Lithium (Al-Li) alloys are known for its properties that are superior to conventional ones. The inclusion of graphene reinforcements to the metal matrix improved strength, stiffness, density reduction, tensile properties, wear, creep, and fatigue resistance. This study examined the combined result of graphene nanoparticles (GNP) and the Al-Li2099 alloy with an ultrasonic-aided stir-casting process. The nano-particulate metal matrix composites with various weight percentages (wt. %) of GNP were fabricated and investigated for physical, mechanical, and microstructural properties. The nanocomposites’ mechanical properties were examined in detail, and significant improvements in hardness, tensile, and compressive strength were observed with higher wt. % of GNP. Theoretical and empirical densities were measured, revealing that the nanocomposite’s densities decrease with the increase in wt. % of nano-reinforcements. Material characterisation of the composites was carried out using XRD, EDAX, SEM, and Fourier-Transformation Infrared Spectroscopy (FTIR). SEM and EDAX confirmed the presence of GNP particulates in the matrix microstructure and elemental composition. The XRD results confirmed the presence of GNP particulates in the Aluminium Alloy (AA) 2099 and the composite, and no other intermetallic elements were detected. The results demonstrated that the GNP addition to the AA2099 significantly enhanced the mechanical and microstructural characteristics of the nanocomposite.

Influence of post-weld rolling and artificial aging on microstructure and mechanical properties of friction stir welded 2195-T4 Al-Li alloy joints

Fiction stir welding (FSW) of a naturally aged (T4) 2195 Al-Li alloy was conducted to study the effect of post-weld artificial aging (AA) and rolling+artificial aging (R+AA) on microstructure and mechanical properties of the FSW joints. Grain features were analyzed by electron back scattered diffraction (EBSD) technology, and precipitates were characterized using transmission electron microscopy (TEM) along [011]Al and [001]Al zone axes. Mechanical properties of the joints were evaluated through micro-hardness and tensile testing. The results indicate that grain development, including grain orientation, grain boundary components and dislocation density, varies within different regions of the As-welded joints due to complicated thermal-mechanical history. The alloying elements mostly exist as Guinier-Preston zones in the base material (BM) with a few formations of δ'/β', and slightly precipitate into T1 in the heat affected zone (HAZ), form σ in the thermal-mechanical affected zone (TMAZ), as well as develop T1 and S' in the nugget zone (NZ) after FSW. The lowest hardness zone (LHZ) exhibits elevated precipitation levels, generating coarse T1 and grain boundary precipitates with evident σ and precipitate free zone. The overall precipitation level of the As-welded joints remains minor, resulting in a slight decrease in hardness at the LHZ. Post-weld AA promotes many T1 formations, enhancing the joint strength and hardness. As a result, the ultimate tensile strength (UTS) of the joints increases from 440 MPa to 506.5 MPa, while the elongation decreases from 13.5% to 3.4%. Furthermore, hardness profiles transform from a low-amplitude wave curve to a high-amplitude W-shaped curve, generating a significant LHZ due to the minimal precipitation of T1. Pre-rolling deformation can enhance dislocation density and low angle grain boundaries (LAGBs), promoting the nucleation of high-density, fine T1 during artificial aging, and especially improves precipitation ability of the LHZ, leading to an elevated hardness increment in the region after AA. Compared to the Joint-AA, both strength and elongation of the Joint-R+AA increase, obtaining 530.5 MPa and 3.9%, respectively.

Microstructure and crack propagation behavior of 2195 aluminum lithium alloy with different orientations in the friction stir welding nugget zone

The 2195 aluminum-lithium alloy is widely used in the aerospace field, where using friction stir welding technology can achieve lightweight and reduced wear designs for components. Fatigue failure, as one of the main modes of damage affecting the life and reliability of structural components, is particularly significant. This paper thoroughly explores the differences in microstructure and fatigue crack propagation behavior between the advancing side and retreating side of the friction stir welded joint in different sampling directions, providing a theoretical basis for enhancing the fatigue performance of friction stir welds. Characterization of the microstructure of the samples was performed using Electron Backscatter Diffraction (EBSD) and X-Ray Diffraction (XRD), and the fatigue properties were investigated using fatigue crack propagation rate curves and crack growth rate curves. The results indicate that the longitudinal base material grains tend to a fibrous structure, while the axial base material grains are distributed in a lamellar fashion. Compared to the advancing side of weld nugget zone, the retreating side of weld nugget zone has significantly reduced grain size and texture types. The fatigue performance of the retreating side of the weld nugget zone is superior to that of the advancing side, and the circumferential welds outperform the longitudinal welds in terms of fatigue performance.

Quantification of precipitate evolution in cast Al–Li alloys containing Cu and Mg additions using small-angle X-ray scattering

Quantification of precipitate evolution in cast Al–Li alloys containing Cu and Mg additions using small-angle X-ray scattering

Enhancing formability in deep drawing: A 3D finite element analysis of plastic wrinkling in AA2090 Al–Li alloy

Deep drawing is a manufacturing process used to produce billions of metal containers, crucial for the aerospace industry in forming thin-walled components efficiently. However, wrinkling due to compressive instability remains a significant challenge in sheet metal forming. This study investigates plastic wrinkling in sheet metal forming to enhance the final drawn shape. A 3D finite element model using ABAQUS/Explicit was developed to examine the effects of mesh topology, blank holder force, and sheet thickness on wrinkling in AA2090 Al–Li alloy. The finding indicates that that an increase in blank holder force increases wrinkle number and amplitude. Additionally, it was found that a 2000 N blank holder force is necessary to prevent wrinkling.

Effect of Rolling and Artificial Aging Treatment on the Microstructure and Mechanical Properties of a 2195 Al–Li Alloy by Ultrasonic Casting

Effect of Rolling and Artificial Aging Treatment on the Microstructure and Mechanical Properties of a 2195 Al–Li Alloy by Ultrasonic Casting

Crack analysis in laser powder bed fusion-fabricated 2195 Al-Li alloy: An in-depth examination of influential variables

Laser powder bed fusion (LPBF) of high-strength 2195 Al-Li alloys offers significant industrial potential, yet the process is hindered by a high susceptibility to hot cracking. This study systematically investigates the hot cracking mechanisms and the key processing parameters influencing crack formation in LPBF-fabricated 2195 Al-Li alloys. Extensive experimental analysis revealed that crack density is significantly affected by scanning velocity and laser power, with scanning velocity identified as the most critical factor through a neural network model and a crack susceptibility model. The study demonstrates that achieving crack-free samples requires extremely low scanning velocities, as higher velocities exacerbate crack formation, particularly at high-angle grain boundaries (HAGBs). The findings also highlight the limitations of preheating in reducing crack susceptibility, emphasizing the importance of precise control over processing parameters to mitigate cracking in LPBF-fabricated 2195 Al-Li alloys.

Synthesis and characterization of lithium alumina silicate (LiAl(SiO3)2) from naturally sourced silica: a comparative study

This study investigates the synthesis and characterization of lithium aluminosilicate (LiAl(SiO3)2) using naturally sourced silica (NSS) from the Djamâa region in Algeria and compares it with laboratory-sourced silica (LSS). The synthesis was conducted using the sol–gel method and solid-state reactions with lithium carbonate, aluminum oxide, and SiO2. Characterization techniques included X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD analysis confirmed the crystalline structure of the synthesized lithium aluminosilicate, revealing distinct crystal phases: the NSS material exhibited a tetragonal spodumene-II phase. In contrast, the LSS material showed a hexagonal spodumene-III phase. The crystallite sizes were 21.96 μm for NSS and 22.14 μm for LSS, with crystallinity percentages of 60.77% and 57.55%, respectively. FTIR spectroscopy verified the successful incorporation of lithium and aluminum into the silica framework. SEM analysis provided detailed insights into surface morphology and particle size distribution, highlighting the uniformity of the materials. Specifically, the LSS material exhibited cylindrical spaces between particles, whereas the NSS material displayed spherical spaces.

Effect of ultrasonic surface rolling on the microstructure and mechanical properties of 2195 Al-Li alloy fabricated by laser powder bed fusion in various build directions

To address the challenges of poor forming quality in the laser additive manufacturing of lightweight alloys, this paper explores an approach that integrates a laser additive manufacturing strategy for lightweight alloys with surface deformation strengthening. The study investigates the combined effects of build direction (BD) and ultrasonic surface rolling (USR) on the microstructure, residual stress, and mechanical properties of 2195 Al-Li alloy processed by laser powder bed fusion (LPBF). The results indicate that changes in BD significantly affect the growth direction of columnar grains (CGs) in the formed specimens and lead to the formation of a gradient microstructure with different characteristics under the influence of USR. When BD is 0°, the post-USR specimen exhibits the most significant deformation strengthening effect, with the high dislocation density reaching depths of up to 720 μm and compressive residual stress amplitudes up to −159 MPa. When BD is 90°, the sample shows excellent tensile performance with an ultimate tensile strength (UTS) of 386 MPa and an elongation (EL) of 8.2 %. After USR treatment, the UTS of the sample increases to 438 MPa, but the EL decreases to 5.1 %. CGs exhibit varying deformation resistances in different directions, thereby influencing the deformation strengthening effect of USR and altering the crack propagation mechanism during the tensile process.

Effect of pulse current on the creep ageing behavior of pre-strained 2195 Al-Li alloy

Pre-strained aluminum lithium (Al-Li) alloy plates have ultra-high strength and comprehensive performance after aging treatments, and are widely used in the aerospace industry. The initial increase in dislocation density caused by these pre-strains will significantly affect the evolution of deformation, microstructure, and mechanical properties during the pulse current assisted creep ageing forming process. Therefore, the effect of pulse current on the creep ageing behavior of 2195 Al-Li alloy with different pre-strains (0%, 4%, and 8%) was investigated. As the pulse current increases within the first 1h creep aging process of the various pre-strain samples, the 1h creep strain significantly increases and the subsequent steady-state creep rate slightly reduce. Moreover, the larger the pre-strain, the higher the total creep strain. Pulse current promotes the movement and recovery of initial dislocations, and promotes the fine formation of T1 phase and suppresses the nucleation of θ' and phase, thereby improving mechanical properties. Compared with the conventional creep ageing process, the pulse current acting on pre-strained 2195 Al-Li alloy significantly increased the peak aged strengthen and shorten the peak aging time. Meanwhile, the peak time platform period has also been significantly extended. It is evident that the application of pulse current assisted creep ageing forming process to pre-strained 2195 Al-Li alloy plates can significantly improve formability and mechanical properties, enlarges the forming process window and realize collaborative manufacturing of Al-Li alloy component shape and performance.

Effect of bath temperature on corrosion resistance of electroless Ni-P coating on 5A90 Al-Li alloy

Abstract The Al-Li alloy exhibits outstanding characteristics, including remarkable specific strength, elevated specific stiffness, and heightened susceptibility to localized corrosion. Electroless Ni-P coating is extensively applied over the appearance of aluminum alloys to enhance their corrosion resistance. Electroless Ni-P coating was applied to 5A90 Al-Li alloy at various plating temperatures for the study presented in this publication. The coating’s surface, composition, and cross-sectional morphology were examined using SEM/EDS. The corrosion behavior of coating was studied using the potentiodynamic polarization curve. Results showed that coating on the surface of 5A90 Al-Li alloy was uniform and smooth. Ni and P elements were evenly distributed in the coating. The thickness of coatings at 80°C, 85°C, 90°C and 95°C was about 3.98 μm, 5.5 μm, 11.2 μm, and 10.29 μm, respectively. As the temperature of the bath increased, the corrosion resistance of the coating first increased and afterward decreased. The corrosion resistance of the coating might be correlated with its thickness.

Precipitation behavior of Al2CuLi, Al3Li and Al3Zr in A2060 aluminum-lithium alloys and mechanical behavior of their microinterfaces

The precipitated phase of Al-Li alloy is a major factor determining the properties of Al-Li alloy. Al2CuLi phase(T1 phase), Al3Li phase and Al3Zr phase are all important enhanced precipitated phases. In this paper, the properties of the matrix, the precipitated phase and the interface formed between each phase are calculated. The (111) crystal face of Al, (111) of Al3Li, (111) of Al3Zr, and (210) of Al2CuLi are the surfaces with the lowest surface energy of these phases. Al3Li/Al3Zr has the lowest interfacial energy (0.01961ev), so its thermodynamic stability is the best. The interface with the maximum bonding strength is the interface of Al3Zr/T1, and its adhesion work is 0.61878ev. A2060 aluminum-lithium alloy was thermally insulated at 580 °C for 2h and then hot rolled. After hot rolling, it was cooled to room temperature for cold rolling. Then the samples were treated with solid solution and aging, and different cooling methods were selected to obtain four kinds of samples: non-heat treatment, aging, air cooling and water quenching. It is found that the strength and hardness of Al-Li alloy are determined by the grain thickness of precipitated phase, and the ductility and hardness of Al-Li alloy are determined by the number of precipitated phase and the degree of dislocation density.

Role of alloying and heat treatment on microstructure and mechanical properties of cast Al-Li alloys: A review

Role of alloying and heat treatment on microstructure and mechanical properties of cast Al-Li alloys: A review

Laser additive manufacturing of Ti and Ce co-modified 2195 difficult-to-process aluminum alloy: Grain refinement, cracking suppression and enhanced mechanical properties

High cracking susceptibility of Al-Li alloys with Ti/CeB6 addition is thoroughly suppressed in laser powder bed fusion (LPBF) processing of Ti/Ce co-modified 2195 alloys at relatively high scan speeds, while the cracking suppression mechanism and phase formation in these composites are not clarified. In this work, microstructure evolution and mechanical performance of the LPBF-fabricated Ti/Ce co-modified 2195 are investigated to reveal their cracking suppression and strengthening mechanisms. The results show that apparent grain refinement of the composites is ascribed to high supercooling from rapid formation of constitutional supercooling zone in front of solid–liquid interfaces by high-Q-value Ti solute, and heterogeneous nucleation of in situ formed Al3Ti and Al11Ce3 precipitates. Their synergistic interactions promote formation of fine equiaxed grains and thus inhibit crack initiation. The composites exhibit high microhardness of 100 ± 5 HV0.2, nano-hardness of 1.6 ± 0.1 GPa and elastic modulus of 97 ± 3 GPa, where the elastic modulus increases by ∼27% and ∼31% compared to those of LPBF-processed and conventionally manufactured 2195 alloys, respectively. A tensile strength of ∼336 MPa and an elongation of ∼3% are obtained from in-situ synchrotron X-ray diffraction measurement. The improved properties are derived from grain refinement and Orowan strengthening. Based on the optimal processing parameter and composition, a bracket component filled with lattice structures is designed and manufactured with good manufacturing quality and processing accuracy.

Influence of friction stir welding on the localised corrosion behaviour of AA2060 T8E30 and AA2099 T83 Al-Li alloys

The effect of friction stir welding (FSW) on the microstructure and localised corrosion behaviour of the dissimilar weld of AA2099 T83 and AA2060 T8E30 alloys is investigated. FSW results in a drastic change in the microstructure thus altering their corrosion behaviour. The heat-affected region exhibits similar attack morphology to their respective base metal but is the most protected region. The stir zone (SZ) is the most susceptible to attack. During immersion of the entire weld, attack initiation occurs from the AA2060 SZ due to galvanic activity within the region caused by the overlap of the grains in the weld zone.

In-situ study on the effect of Li concentration on hydrogen microporosity evolution in Al-Li alloys by synchrotron X-ray radiography

The nucleation and growth of hydrogen microporosity during the solidification of Al-Li alloys were in situ observed by synchrotron radiation X-ray radiography, and the effect of initial Li concentration on its evolution kinetics was investigated. The results show that the high Li concentration effectively contributes to the high-temperature nucleation effect of hydrogen microporosity during the solidification of Al-Li alloys, and significantly increases the nucleation and growth rates of hydrogen microporosity. When the initial Li concentration was 2.0 wt%, the nucleation supersaturation of hydrogen microporosity was 1.96, which was 3.5 times higher than that at low Li concentration (1.5 wt%), and the growth rate was up to 2.61 μm/s. In addition, the quantitative results of the final size, morphology, and distribution of the hydrogen microporosity based on 3D X-ray computed tomography (X-CT) showed that high Li concentration not only increased the volume of monolithic hydrogen microporosity, and increased the total number of microporosities, but also increased the degree of irregularity of hydrogen microporosity. The in-situ observation results can provide a new dataset for the establishment and validation of the hydrogen microporosity model of Al-Li alloys.

Microstructural Evolution, Precipitation Behavior, and Mechanical Property Response of Cast Al–Li–Cu–Cd–Mn–Zr–Ti Alloy

The microstructural evolution and mechanical properties of cast Al–Li–Cu–Cd–Mn–Zr–Ti alloy during heat treatment are investigated systematically. In these findings, it is shown that the as‐cast alloy exhibits fine and equiaxed grains. During the solid solution treatment, Al20Cu2Mn3 dispersoids effectively restrict grain growth, and reducing the solid solution time has a similar effect. Subsequently, the precipitation behavior and its effect on the mechanical properties during the aging process are revealed. Al3(Ti, Zr) particles are uniformly distributed throughout the matrix, acting as nucleation sites for δ′, θ′, and T1 precipitates. Overtime, δ′ precipitates gradually coarsen and decrease in number, and some δ′ precipitates attach to Al3(Ti, Zr) particles, forming core–shell Al3(Li, Ti, Zr) phases. At the same time, plate‐shaped θ′ and T1 precipitates emerge and coarsen. After aging at 160 °C for 24 h, the alloy exhibits an excellent combination of strength (yield strength =293.3 ± 4 MPa, ultimate tensile strength =468.0 ± 3 MPa) and ductility (elongation =9.6 ± 0.4%), surpassing those reported in other cast Al–3Li–2Cu–X alloys. Critically, the underlying mechanisms behind the microstructure and mechanical properties are discussed extensively, providing valuable insights for the advancement of cast Al–Li alloys.

Thermodynamic re-assessment of the Al-Li-Zn system

Aluminum-lithium alloys are a kind of highly promising material due to low density, high strength and excellent modulus properties. The proper addition of Zn can effectively promote the precipitation of the main metastable strengthening phase δ′(Al3Li). As a crucial sub-system of Al-Li alloys, literature data on phase diagram and thermodynamic properties of the Al-Li-Zn system as well as the Al-Li and Li-Zn binary systems were comprehensively evaluated by the CALPHAD approach. The Li-Zn system was reassessed mainly by considering the newly reported data on formation enthalpy and activity and a 2-sublattice (SL) model was applied to describe the βLiZn4 phase. The Al-Li system was modified by considering AlLi2 and describing the metastable phase δ′(Al3Li) with interconvertible 4SL and 2SL ordered-disordered models. The predicted metastable fcc solvus was in perfect agreement with the measurements. Considering the available experimental data, the ternary Al-Li-Zn system was then re-optimized and a self-consistent thermodynamic description of the ternary Al-Li-Zn system was presented. The predicted metastable two-phase region of (Al)+δ’(Al3Li) in Al-Li-Zn system can be coupled with the accessible experimental data, which can be expected to well assist in designing high-strength Al-Li alloys.