Al Zn Research Articles

Effect of microwave melting and subsequent rolling on the corrosion behavior and electrochemical properties of an aluminum anode using response surface methodology

To obtain aluminum-air batteries with a high anodic efficiency and low corrosion rate, it is necessary to study the methods by which their aluminum alloy anodes are prepared. Here, the performance of an aluminum alloy anode was optimized by microwave melting and rolling. The aluminum anode showed the best performance under a 1000 W microwave power, two passes, and 40% reduction degree (sample denoted 1000W-2–40%). Under these conditions, the grain size of the Al–Zn–Bi–Pb anode was uniform, and no intergranular corrosion was observed. The corrosion resistance was high, and the anodic efficiency reached 72.72%. Finally, by observing the microstructure of an aluminum anode obtained under 1000 W microwave treatment, the corrosion mechanism was analyzed. The activity of the rolled aluminum anode was improved due to the existence of ZnAl2O4 phase. However, in 1000W-1–30%, 1000W-2–20%, and 1000W-3–30% samples, fine grains precipitated at high-angle grain boundaries. The grain orientation was mainly (110), which led to the intergranular corrosion of a large area of the anode, which made it unsuitable for use in aluminum-air batteries.

Microstructural and Mechanical Behavior Investigations of Nb-Reinforced Mg–Sn–Al–Zn–Mn Matrix Magnesium Composites

This research focuses on the fabrication and characterization of TAZ532-xNb composites, employing high-purity, micron-sized powders of Mg, Sn, Al, Zn, Mn, and Nb as the raw materials. These powders were subjected to a paraffin coating process aimed at mitigating oxidation. The formation of composites was achieved via hot pressing and was followed by surface preparation and analysis using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). An X-ray diffraction (XRD) study was conducted to identify the microstructural phases. Quantitative assessments including the theoretical density, actual density, and relative density were computed, and their fluctuations in relation to the increasing Nb reinforcement ratio were scrutinized. Furthermore, the mechanical attributes of the composites, such as hardness and tensile strength, were assessed via experimental procedures. The absence of oxygen-related peaks in the XRD patterns endorsed the successful execution of the paraffin coating technique and protective gas atmosphere during sintering. The detection of α-Mg, Mg2Sn, MgZn, Mg17Al12, and Nb phases within the Nb-reinforced composite patterns authenticated the formation of the intended phases. Notably, the relative density values of the composites surpassed 95%, indicating efficient sintering. SEM results disclosed a densely packed microstructure, with Nb reinforcement particles evenly distributed along the grain boundaries, devoid of particle clustering or significant grain growth. These composites manifested exceptional wetting characteristics, which can be attributed to the employment of Mg alloy as the matrix material. EDS data confirmed the proportions of Nb within the composites, aligning with the quantities incorporated during fabrication. The composites showcased an increase in microhardness values with the escalating Nb reinforcement ratio, credited to the harder constitution of Nb particles in comparison to the matrix alloy. Concurrently, tensile strength showed a significant improvement with the increment in Nb reinforcement, while elongation values peaked at a specific Nb reinforcement level. The positive evolution of tensile strength properties was ascribed to the escalated Nb reinforcement ratio, grain size, and consequent higher sample densities.

Influence of the precursors in CuZnAl slurry catalyst preparation by the complete liquid phase for the ethanol synthesis from syngas

It has been found that CuZnAl slurry catalyst performance is influenced seriously by its precursors in ethanol synthesis from syngas. Herein, a series of the slurry catalysts were prepared by complete liquid phase method adopting different sol-gel and solution as components of precursors. Their catalytic performances were investigated in a slurry bed reactor and physicochemical properties were characterized by XRD, H2-TPR, NH3-TPD, N2 adsorption and XPS techniques. The results show that the catalyst Al–Zn(g)-Cu(s) prepared by adopting Zn gel and Cu solution as components of precursors exhibits the highest ethanol synthesis capacity, with the proportion of ethanol in the total alcohol reaching up to 45.36%. And no visible deactivation was detected over 168 h reaction. Characterization indicates larger Cu0 particles and a suitable range of surface Cu0/(Cu0+Cu+) ratios are favorable to the production of ethanol, the Cu0/(Cu0+Cu+) ratios can be adjusted partly by Cu0 particle sizes.

Aluminum and Zinc Co-substituted Cobalt Ferrite: Structural, Magnetic, and Magnetostrictive Properties

We report on the influence of Al and Zn co-substitution on the structural, magnetic, and magnetostrictive properties of cobalt ferrite (Co1–xZnxFe2–xAlxO4, 0 ≤ x ≤ 0.15; CZFAO) materials, which were made using a glycine-nitrate autocombustion process. The cubic spinel structure is present in both the as-synthesized and the sintered CZFAO samples, where it was evident that the crystallite size and lattice parameter reduced with increasing x due to the incorporation of smaller Al3+ ions in place of larger Fe3+ ions in spinel ferrite. Co-substitution induced changes in the metal–oxygen bond lengths, causing both the tetrahedral and octahedral infrared and Raman spectroscopic bands to shift toward higher wavenumbers. The electron microscopy analyses indicate that the Al–Zn substitution induces grain growth, leading to a dense, interconnected grain morphology. Mossbauer analyses indicate that the Al3+ occupies the octahedral site, whereas Zn2+ is substituted at the tetrahedral site. Due to equal magnetic dilution of both tetrahedral and octahedral sites caused by the presence of Zn and Al at the appropriate sites, the saturation magnetization MS of CZFAO is the same as that of pure CFO. All other magnetic parameters (coercivity HC, magnetocrystalline anisotropy constant K1, and Curie temperature TC) decrease with increasing x, where the decline observed is mostly due to superexchange interaction (A-O-B) reduction caused by the substituents’ non-magnetic character. CZFAO materials exhibit higher magnetostriction strain λ and strain sensitivity dλ/dH at relatively low magnetic fields; among all the samples, x = 0.15 demonstrates a maximum strain sensitivity of −2.53 × 10–9 m/A at 23 kA/m magnetic field. The composition-tuned CZFAO materials with desirable properties are suitable for application in torque sensors.

Understanding the effect of deformation combined with heat treatment on age hardening of Al–Zn–Mg–Cu alloy AA7075

Al–Zn–Mg–Cu alloys obtain their exceptional high strength predominately relying on precipitation. Deformation can influence the evolution of precipitation and may potentially provide additional strength through work hardening. In this study, the coupling of dislocation and precipitation strengthening to achieve unique property combinations with strengths greater than those due to heat treatment alone was investigated on pre-aged AA7075 subject to a pre-age, deform, post-age cycle. The evolution of precipitates and mechanical properties were characterised to understand the contribution of each mechanism to the final strength. Small angle X-ray scattering (SAXS) was used to monitor the precipitate evolution during post-ageing, with the support from transmission electron microscopy (TEM) and isothermal calorimetry. The results revealed that uni-axial deformation to 10% strain had negligible effects on pre-existing precipitates but introduced sufficient dislocations to enable significant work hardening, which resulted in strengths greater than those obtained with a T6 heat treatment but with a sacrifice in further strain to failure. Post-ageing at 120 °C was found being effective on partially recovering dislocations and promoting precipitation strengthening. A simple model was applied to demonstrate that the time required to reach peak strength is determined by the competing effects of the enhanced kinetics of precipitation and dislocation recovery. The acceleration effect of prior deformation on the growth of precipitation during post-ageing is consistent with the expected effect of dislocations acting as the fast diffusion paths.

Dynamic recrystallization mechanisms of as-forged Al–Zn–Mg-(Cu) aluminum alloy during hot compression deformation

The thermal deformation behavior of as-forged Al–Zn–Mg-(Cu) aluminum alloy at strain rate 0.001–1 s−1, temperature 663–783 K and deformation degree 0–60% was studied by isothermal compression test, and an accurate strain-compensated Arrhenius constitutive equation was established. Based on the microstructure characteristics of compressed specimens, the effects of strain rate, temperature and strain on dynamic recrystallization (DRX) behavior and substructure evolution were determined. The results show that the alloy undergoes discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX) and geometric dynamic recrystallization (GDRX) simultaneously at high temperature and low strain rate (743 K, 0.001–0.01 s−1), where CDRX includes microshear band assist (MSBA), homogeneous increase of misorientation (HIM) and progressive lattice rotation near grain boundaries (LRGB). However, with decreasing temperature and increasing strain rate, GDRX basically disappears, and DDRX becomes the main DRX mechanism. At medium to high strain rate (0.1∼1 s-1), high-density dislocations accumulate at the grain boundaries and numerous microshear bands form inside grains during the early deformation stage. The misorientation angles of these pre-existing geometrically necessary boundaries gradually increase with temperature and strain, ultimately transforming into subgrains and DRX grains.

The Structure and Properties of Sheets of the Al–Zn–Mg–Cu–Zr–Y(Er) Alloy Doped with Manganese

The Structure and Properties of Sheets of the Al–Zn–Mg–Cu–Zr–Y(Er) Alloy Doped with Manganese

A trade-off between mechanical strength and electrical conductivity of Al–Zn–Mg–Cu alloy via Ag alloying and retrogression re-aging heat treatment

The effects of silver (Ag) alloying and a retrogression re-aging heat treatment on the mechanical properties and electrical conductivity of the Al–Zn–Mg–Cu aluminum alloy were studied by means of tensile test, electrical conductivity test, and transmission electron microscopy (TEM). A trade-off between the mechanical strength and electrical conductivity was achieved, with the former reaching 558 MPa and the latter reaching 45.1 IACS. The alloy was prepared through a retrogression re-aging heat treatment (120 °C/6 h + 160 °C/7 h + 220 °C/0.5 h + 120 °C/24 h) performed on the solution and quenched samples. Furthermore, through TEM analysis of the sample solution treated at Temperature Ⅰ (420 °C/3 h + 470 °C/2 h) and Temperature II (420 °C/3 h + 480 °C/2 h), indicates that the Ag interacts with zinc or magnesium to form small clusters, which can act as precursors for η′ precipitates. η–type precipitates were the dominant precipitated phase, and the precipitation sequence was supersaturated solid solution (SSS)→ small clusters → Guinier–Preston (GP) zone → η′ → η. Furthermore, after the retrogression re-aging heat treatment, a large amount of GP (Ⅱ) and η′ precipitated in the matrix. GP (Ⅱ) and the η′ phase are related to the precipitation of {111} Al crystal plane, it is thus speculated that the interaction between the η′ phase and GP (Ⅱ) or nanosized Al3Zr dispersoids contributes to the strength of the alloy. Moreover, the retrogression re-aging heat treatment promotes the precipitation of the second phase, which can purify the matrix and reduce lattice distortion, thus improving the conductivity of the alloy.

Microstructural evolution of aluminium in dissimilar A1050/S45C FSW joints by Zn interlayer

This study investigated the microstructural evolution of A1050 stir zones in dissimilar A1050/S45C friction stir-welded joints fabricated with 100- and 200-µm-thick Zn interlayers in addition to a third joint without any interlayer. The dissolved Zn in the A1050 stir zones contributed to its strengthening by forming Al–Zn solid solution. The addition of Zn refined the A1050 grains with many well-defined high-angle grain boundaries. The effect of Zn in the A1050 strengthening and grain refinement becomes apparent with a relatively high content of Zn. The possible precipitation of Zn-rich particles along the A1050 grain boundaries may also contribute to the A1050 stir zone strengthening by retarding the dislocation motion and enhancing the discontinuous dynamic recrystallisation.

Constitutive modelling of coupled creep deformation and age hardening behavior of aluminum alloys under various thermal and mechanical loadings

A new theoretical-based constitutive model has been proposed in this study to concurrently predict the ageing and coupled creep-ageing behavior in both micro and macro ways of aluminum alloys under complex thermal and mechanical loading histories. The nucleation, growth and coarsening theories for age strengthening of aluminum alloys have been modified with the integration of dislocation-based theories raised by plastic or creep deformation to form the new theoretical-based creep-ageing modelling framework. Both the key microstructures (precipitates, solid solutes and dislocations) and macro properties (creep/stress-relaxation, yield strength and strengthening components) under various thermal and loading histories (e.g., single-step/multi-step isothermal and non-isothermal, pre-strain loaded) of a typical Al–Zn–Mg alloy have been effectively predicted and validated by the same set model. Furthermore, the capability of the developed model to reveal the detailed deformation and strengthening mechanisms with complex thermal and loading histories, and to assist the design of complex non-isothermal creep-ageing processes with optimization objectives of accurate shape and high strength in the formed alloys has been discussed and demonstrated.

Thermal Kinetics of Varying Weight Fraction of Silicon Carbide Reinforced Al–Zn–Mg–Cu Alloy Composite

Thermal Kinetics of Varying Weight Fraction of Silicon Carbide Reinforced Al–Zn–Mg–Cu Alloy Composite

Towards enhancing the ductility of AZ31 Mg alloys by controlling twin orientation at various shear strain levels

In this work, a novel texture control strategy, shear strain-induced twin orientation regulation (SITOR), was employed to fabricate the Mg–3Al–1Zn (AZ31) alloy with significantly improved ductility. The SITOR-1P sample processed at 250 °C exhibited a homogeneous microstructure and an almost ideal shear texture (c-axes of grains tilted 45° from the extrusion direction to the transverse direction), which resulted in an enhanced fracture elongation from 14.3% to 30.6% owing to the high activity of basal slip when compared with as-extruded Mg alloys. With increasing shear strain, the concentration of shear texture components in the SITOR-4P sample increased, leading to further improvement in its mechanical performance. While specimens produced by the conventional shear strain-induced orientation regulation (SIOR) method also underwent the same 4 passes of shear deformation, both their texture deflection and performance enhancement remained limited. The current investigation proposes a viable way to largely activate basal slip via the SITOR scheme, therefore offering a fresh perspective for addressing the poor plasticity of Mg.

Interfacial microstructural evolution and mechanical properties in dissimilar A1050 aluminium and S45C carbon steel friction stir welded joints using Zn interlayers

This study investigated the effect of Zn interlayers on the dissimilar friction stir welding of A1050 pure aluminium and S45C carbon steel. Two joints were made by adding Zn foils of two different thicknesses (100 μm and 200 μm) between the A1050 and S45C base metals in addition to a third joint without any interlayer. The joining experiments were conducted in constant process parameters at tool rotational speed and welding speed of 1500 rpm and 250 mm/min, respectively. The differences in joints microstructure were correlated with their mechanical properties and fracture mode. The results showed that Zn inhibited the growth of the interfacial Al–Fe IMCs, altered their composition and contributed to strengthening the A1050 stir zones by forming Al–Zn solid solution. Compared to the Zn-free joint, the ultimate tensile strength of the joints fabricated with the 100 μm and 200 μm thick Zn interlayers was improved by 14% and 26%, respectively. Also, the brittleness inside their interfacial IMCs was eliminated. As a result, the joints fabricated with Zn interlayers exhibited higher elongation and their fracture occurred at the A1050 instead of the joint interface as in the Zn-free joint. The Zn interlayer is expected to widen the joining process window by minimizing the detrimental effects of the Al–Fe IMCs.

The contribution of grain boundary sliding to the deformation in an ultrafine-grained Mg–Al–Zn alloy

The contribution of grain boundary sliding to the deformation in an ultrafine-grained Mg–Al–Zn alloy

Thermal stability of nanocrystalline surface layer in an aged Al–Zn–Mg–Cu alloy induced by ultrasonic surface rolling processing

This paper investigates the thermal stability of nanocrystalline surface layer in an aged Al–Zn–Mg–Cu alloy fabricated by ultrasonic surface rolling process (USRP). The microstructure of the nanocrystalline surface layer and the microstructure changes of grains and precipitates in the nanocrystalline surface layer after annealing at various temperatures were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The microhardness after annealing was also analyzed. The results show that a nanostructured lamella with a thickness of about 40 nm was prepared in the surface layer of the aged Al–Zn–Mg–Cu alloy after USRP. The granulation of the nanostructured lamellae occurs during subsequent annealing due to recovery and becomes more significant with the increase of annealing temperature. Besides, the coarsening η phases occur at the lamellae boundaries by heterogeneous nucleation. Meanwhile, the precipitate inside lamellae gradually changes from GP zone and η' phase to η phase. The thermal stability of the nanostructured lamellae is excellent below 160 °C, but it deteriorates significantly when the temperature exceeds 200 °C. The hardness variation of the nanostructured lamellae is mainly determined by the variation of lamellae thickness and the precipitation behavior plays an auxiliary role.

Mechanical Characterization of B4C-Gr Reinforced Al–Zn–Mg Alloy Hybrid Nanocomposites

The current study is an attempt made to synthesize nano B4C/Graphite reinforced Aluminum–Zinc–Magnesium alloy composites by altering the weight %age of B4C (2%, 4%, and 6%). SEM was used to examine the morphology and mechanical behaviour was done in accordance with ASTM standards (ASTM E8, E9, E23, and D790). The microstructure displays a nearly uniform dispersion of reinforcement particles in the matrix alloy, with no residual pore visible. From the XRD analysis it is identified that interfacial phases between the base material and ceramic strengthening particulates are identified as Al3BC, AlB12, Mg2Si, SiAl2 and it strive as strengthening mechanism of synthetic composites. The interfacial phases identified as Al3BC, AlB12, Mg2Si, and SiAl2, and serve as a strengthening mechanism for synthetic composites, according to XRD. When compared to the base material, intermixtures had higher hardness (28.07%), ultimate tensile strength (69.31%), compressive strength (18.58%). The flexural strength is improved (29.32%) due to higher dislocation density in the matrix and wider variations in the elastic modulus. The impact strength improved significantly (72%) due to a reduction in porosity and grain refinement.

Correlating surface topography of relaxed layer of ZA/ZrB2 in situ composites to wear and friction

In the present study, the correlation between the surface topography of relaxed layer and wear and friction has been investigated. For this purpose, the lubricating tribology and surface topography of insitu formed ZrB2 reinforced Zn-Al (ZA) composites have been studied. The wear and friction properties of composites have been evaluated on a pin-on-disc tribometer under synthetic SAE20W40 motor oil. The worn surface has been studied by SEM, AFM, and profilometer. Results indicate high wear resistance and low COF with smoother topography with ZrB2 reinforcement. The composite with 9 vol. % ZrB2 exhibits lower kurtosis and negative skewness values confirming the smoother topography with higher load-carrying capacity. This composite exhibits little wear and COF even at higher loads and sliding distances in the presence of lubricant. A comparative study with existing tribological materials indicates that the present materials have huge potential to be used as bearings and bushings.

Enhanced precipitate strengthening in particulates reinforced Al–Zn–Mg–Cu composites via bimodal structure design and optimum aging strategy

Depletion of solutes on particle-Al interfaces in particulates reinforced precipitate-hardening Al composites was harmful to strength. A two-step strategy including bimodal structure design and dislocation assisting low-temperature aging was proposed to enhance the precipitate strengthening in composites. Bimodal structures can redistribute the dislocations from vicinities of particles to coarse grains and increase the density of GNDs under a low strain pre-deformation. Subsequent low-temperature aging at 373 K can eliminate the coarse phases and precipitate-free zones on both grain boundaries and phase interfaces and introduce dense plate precipitates with large aspect ratio in {111}Al planes, contributing to an ultrahigh strength in bimodal composites without the sacrifice of ductility.

Fabrication of micron-sized three-dimensional porous Al from an Al–Zn monotectoid alloy via selective etching and Al passivation

Fabrication of micron-sized three-dimensional porous Al from an Al–Zn monotectoid alloy via selective etching and Al passivation

Effect of Homogenization Process on Microstructure of Al–Zn–Mg–Cu Aluminum Alloys

Herein, the best homogenization process of 466.5 °C × 36 h + 490 °C × (14–26.4 h) that can completely eliminate the coarse phases σ[Mg(Zn, Al, Cu)2] and S(Al2CuMg) in the Al–Zn–Mg–Cu aluminum alloy is developed. The homogenization process is determined by the method of calculation phase diagram, and the experimental verification. It is shown in the results that, first, in the microstructure of the as‐cast alloys, the crystal structure of the σ[Mg(Zn, Al, Cu)2], Al7Cu2Fe, and Mg2Si phases is determined. Second, during the homogenization process, the σ[Mg(Zn, Al, Cu)2] phase dissolves and also transforms into the S(Al2CuMg) phase. Most importantly, the dissolution temperature range of the σ[Mg(Zn, Al, Cu)2], S(Al2CuMg), and Al7Cu2Fe phases is determined from 472.56 to 476.36 °C, from 484.09 to 485.39 °C, and from 540.18 to 547.23 °C, respectively. At best homogenization process, the residual Al7Cu2Fe phase area fraction ranges from 1.28 ± 0.16% to 1.60 ± 0.18%. In addition, dispersed η(MgZn2) phase precipitates in supersaturated Al‐matrix during differential scanning calorimeter heating. And, the concentration differences between the grain center and the eutectic of structure of Zn, Mg and Cu regression equations are established, which can provide some reference for the design of experimental parameters, thus reducing the experimental workload.