Al Zn Research Articles

Study on hot deformation behavior and dynamic recrystallization mechanism of recycled Al–Zn–Mg–Cu alloy

This study utilized Al–Zn–Mg–Cu alloy chips as raw materials to prepare recycled billets through a solid-state recycling process. Isothermal hot compression tests were conducted using a thermal simulation machine to establish an Arrhenius-type constitutive equation and the hot processing map based on the dynamic materials model. The microstructure of the recycled Al–Zn–Mg–Cu alloy after hot compression was characterized and analyzed using SEM, EBSD, and TEM, exploring the microstructural evolution mechanisms of the recycled alloy at different temperatures and strain rates. The results indicate that the optimal hot deformation parameters for the recycled Al–Zn–Mg–Cu alloy are 300–360 °C at a strain rate of 0.01–0.05 s⁻1 and 400–450 °C at a strain rate of 0.05–0.3 s⁻1. At the same strain rate, as the deformation temperature increases, low-angle grain boundaries gradually disappear, and the grain structure becomes more stable. Dynamic recrystallization replaces dynamic recovery as the dominant mechanism. At the same deformation temperature, low strain rates allow more time for the migration of low-angle grain boundaries, thereby promoting the growth of dynamically recrystallized grains and ultimately forming new, undistorted grains.

Microstructural Evolution During Homogenization of Direct-Chill-Cast Al–Zn–Mg–Cu Alloy

Microstructural Evolution During Homogenization of Direct-Chill-Cast Al–Zn–Mg–Cu Alloy

Experimental investigation of FSW induced property changes in welded dissimilar Mg–Al–Zn alloys

Intense plastic deformation and intermixing during friction stir welding of dissimilar alloys may suppress the properties in welded zone. To suitably control these changes, careful study is required. Present research investigates microstructure, mechanical performance and corrosion behaviour at different rotational speeds in friction stir welded dissimilar AZ31–AZ91 Mg alloys. Very small cracks were present in welded zone due to formation of magnesium oxide (MgO). The EBSD analysis suggest more concentrated fibre texture at 1000 rpm tool rotational speed as compared to 700 rpm tool rotational speed in welded zone and the texture maximum intensity was 39.447 times of random distribution at tool rotational speed of 1000 rpm. The obtained maximum microhardness was 82 Hv at tool rotational speed of 700 rpm. The maximum values of tensile strength (234.86 ± 7.77 MPa) and flexural strength (350.89 ± 17.67 MPa) of welded samples were decreased as compared to base materials. The corrosion rate of welded samples was increased and corroded surface have some pits and corroded rings. The highest corrosion rate (2.1596 mm / year ) was obtained at 700 rpm. This experimental work suggests that in overall, sample welded at 1000 rpm tool rotational speed has better weld property.

The characteristics of Zn–5Al–2Mg coating on low carbon steel by two-step galvanizing method

The aim of this work is to characterize the complicated microstructure of a multilayer material that has been produced using a two-step batch galvanizing technique, with a particular focus on its extraordinary resistance to corrosion. The corrosion testing was performed using cyclic salt spraying, which involved the use of a salt mist chamber, wet chamber, and dry chamber. The results indicated that the Zn–5Al–2Mg (ZMA) coating system consists of four distinct layers: α, β, θ, and π layers. The top layer consisted of ternary and binary eutectic phases, whereas the central section had a branch-like Fe4Al13 phase. A continuous layer of Fe4Al13 was produced at an interface with the substrate. After undergoing 270 corrosion cycles, the coating demonstrated the capability to generate corrosion products that were dense and compact, including Zn5(OH)6Cl2H2O, Zn5(CO3)2(OH)6, and Mg6Al2(CO3)(OH)16⋅H2O. The corrosion products inhibited the corrosive substance from reaching the steel substrate, hence enhancing the durability of the coating.

Microstructures, mechanical properties and damping performance of wrought Mg–Cu–Ca alloys

Mg–Cu–Ca alloy sheets show good room temperature formability and excellent thermal conductivity; however, their strength is insufficient for load-bearing applications. In this study, Mg–Cu–Ca ternary alloys were subjected to a conventional extrusion process, and the microstructures and tensile properties were systematically evaluated. The addition of extremely small amounts of Cu and Ca to pure Mg (Mg–0.03Cu–0.05Ca, wt%) led to significant refinement of dynamically recrystallized (DRXed) grains while preserving a certain fraction of un-DRXed grains, which contributed to a substantial increase in tensile yield strength. Adjusting the extrusion parameters further increased the tensile yield strength to 329MPa, driven by the combined effects of further refined DRXed grains and an increased area fraction of un-DRXed grains. The damping performance of the Mg–0.03Cu–0.05Ca alloy sheet was superior to that of commercial AZ31(Mg–3Al–1Zn–0.3Mn in wt%) alloy sheet but lower than that of pure Mg, particularly at low frequencies. This revealed that the solute segregation at grain boundaries plays a crucial role in the damping performance of Mg alloys.

Dispersoid evolution in Al–Zn–Mg alloys by combined addition of Hf and Zr: A mechanistic approach

Coherent Al3X-type L12-structured dispersoids have the potential of effectively stabilizing the grain structure and increasing strength. This concept has been successfully demonstrated for non-hardenable and rapidly solidified Al alloys. In precipitation-hardened Al alloys, effective dispersoid addition requires both controlling their high-temperature stability and minimizing their impact on precipitation hardening. The current study focuses on dispersoid-modified AlZn5.0 Mg1.2 alloys, which exhibit MgZn precipitation upon age-hardening and include less than 1 wt% of Zr and Hf for dispersoid formation. Heat treatments between 350 °C and 500 °C for varying times were applied to evaluate dispersoid formation, thermal stability and the related strengthening potential. The microstructure was assessed using transmission electron microscopy (TEM) and atom probe tomography (APT), and the mechanical response was evaluated by hardness testing. TEM after heating at 500 °C reveals Ostwald ripening for the dispersoids. APT results on the dispersoids reveal a core–shell structure development upon longer annealing times. The Zr–Hf-modified alloy exhibits a higher initial strength than the Zr-modified alloy but the latter displays greater strength retention even after prolonged exposure to 500 °C. This effect is attributed to a destabilization of the mixed Zr–Hf dispersoids that arises from lower enthalpic benefits of Al3Hf formation over Al3Zr.

Enhanced combustion performance of Al–Zn alloys with property optimization inspired by “two-way tunneling” strategy

Fluorinated polymers (PVDF) are widely used due to their pre-ignition reaction with Al2O3 to improve the combustion of Al. In this study, a homogeneous PVDF coating layer was constructed on the surface of Al–Zn alloys by solvent evaporation, and Al-Zn@PVDF composites with “two-way tunneling” function during thermal decomposition and combustion were prepared. The constructed PVDF coating layer can react with Al2O3 to destroy the protective layer and promote the oxidation and combustion of Al–Zn from the outside to the inside. At the same time, the energy provided by the Al-Zn@PVDF during the ignition and combustion process also promotes the melting and vaporization of Zn, which achieves the rapid and full combustion of Al–Zn alloy from the inside to outside. The “ two-way tunneling” function of Al-Zn@PVDF composites significantly improves the combustion performance, resulting in a maximum combustion temperature of 1346.9 °C for Al-Zn@PVDF-40 % and a minimum combustion duration of 1.39 s for Al-Zn@PVDF-30 %, which is a significant improvement in combustion performance. The good chemical stability of PVDF also improves the hydrophobicity of Al–Zn and enhances its applicability. In conclusion, the construction of composites with “two-way tunneling” function first proposed in this study can significantly improve the thermal decomposition and combustion properties of Al–Zn, which is expected to further facilitate its application in propellants, explosives and pyrotechnics.

Elimination of cracks in Al–Zn–Mg–Cu alloy by addition of TiO2 in selective laser melting

7050 aluminium alloy is widely used in aerospace industry due to its excellent mechanical properties. 7050 aluminium alloy belongs to Al–Zn–Mg–Cu alloy. Due to the formation of cracks in selective laser melting (SLM) forming of Al–Zn–Mg–Cu alloys, 7050 aluminium alloy is difficult to be applied to forming and manufacturing in this technological field. In order to solve this critical problem, in this paper, titanium dioxide (TiO2) powder was mixed with 7050 aluminium alloy using ball milling method to achieve the effect of eliminating cracks. The cracks in the specimens completely disappeared when the TiO2 additions were 1.5 wt% and 2 wt%. With the addition of TiO2, the grains gradually changed from coarse columnar crystals to fine equiaxed crystals. Combined with the temperature field simulation, the grain refinement and crack elimination mechanism of TiO2 in SLM forming were analysed. The grain refinement is attributed to the formation of Al3Ti. The crack elimination was attributed to the reduction of the intergranular solid-liquid channel length. The maximum values of tensile strength and elongation of 7050 aluminium alloy formed by SLM are achieved at 2 wt% of TiO2. The values are 389 MPa and 8.8 %. The better mechanical properties were attributed to the synergistic effect of crack elimination, Hall-Petch, and Orowan strengthening. This study provides experimental guidance for the preparation of crack-free 7050 aluminium alloy.

The effects of deformation parameters on the second phases and softening behavior of Al–Zn–Mg–Cu alloys

This study investigates the effects of deformation parameters on the second phase and softening behavior of Al–Zn–Mg–Cu alloy. The results are as follows: Firstly, the area fraction of the intermetallic phase fluctuates between 0.704 ± 0.092% and 1.886 ± 0.231% with varying deformation parameters. Secondly, in the temperature range of 270 °C to 430 °C, the area fraction of the η[Mg(Zn, Al, Cu)2] phase first increases and then decreases with rising deformation temperature, and gradually increases with decreasing strain rate. The highest area fraction is 12.613 ± 0.340% at 350 °C/0.001 s−1, and the lowest is 0.366 ± 0.068% at 470 °C/0.001 s−1. Additionally, the coarsening and dissolution of the η[Mg(Zn, Al, Cu)2] phase accelerate the dynamic recovery softening of the alloy. The sample at 350 °C/0.001 s−1 shows a low-angle grain boundary (LAGBs) percentage of 97.83% and a minimum average dislocation density of 8.493 × 102 μm2. Furthermore, at 470 °C/0.001 s−1, the Al7Cu2Fe phase has a weaker effect on stimulating nucleation and recrystallization, while the most significant promotion occurs at 430 °C/0.001 s−1. In the range of 270 °C to 350 °C and 0.1 s−1 to 0.5 s−1, the Al7Cu2Fe phase mainly stimulates the formation of sub-grains. These findings offer valuable insights for refining the grain size of alloys by regulating the content of the second phase during hot deformation.

Microstructure Evolution and Mechanical Properties of In Situ TiB2/Al–Zn–Mg–Cu Composites by Electropulsing‐Assisted Solution Treatment

The traditional solution treatment is not completely applicable for in situ TiB2/Al–Zn–Mg–Cu composite due to the influence of TiB2 particles. This study investigates the impact of the electropulsing‐assisted solution (EAS) process on the microstructure evolution and mechanical properties of TiB2/Al–Zn–Mg–Cu composites. The nonuniform microstructure evolution related to the difference in temperature and current density is supported by simulative and experimental results. EAS treatment significantly enhances the degree of supersaturation, allowing phases surrounding TiB2 particles to dissolve without extensive overburning, unlike traditional solution treatments. This improvement is attributed to the reduced thermodynamic barrier and accelerated atomic diffusion, facilitated by both localized and average Joule heating effects and enhanced thermal electron/phonon scattering. Meanwhile, grain size remains stable during the temperature rise induced by EAS treatment. Furthermore, the mechanical properties of composites increase, among which the increase in strength is mainly ascribed to solid–solution strengthening, and the increase in elongation is related to multiple factors referring to TiB2 particles fracture and interface crack between the undissolved phases and matrix. This study provides an approach to achieve an efficient dissolution of phases aggregated with particles and without widespread overburning in particle‐reinforced Al matrix composites via electropulsing techniques.

Uncovering the combining V with Ni micro-addition alloying on the mechanical properties and multiphase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc alloy

The ultimate tensile strength of the T6-aged Al–Zn–Mg–Cu–Sc alloy is improved by 24 MPa reached 667 MPa with the addition of 0.10 % V, 0.20 %Ni and decrease 0.1 %Sc. The thermodynamic and microalloying mechanisms of phase transformation during solidification and homogenization of Al–Zn–Mg–Cu–Sc–V–Ni alloy were clarified. The phase transformation model of Al3Sc (V, Ni) structure induced by V and Ni addition during homogenization was established. The calculation radius showed that coherent L12-ordered Al3Sc(V, Ni) nanoparticles were formed in the Al–Zn–Mg–Cu–Sc–V–Ni alloy, which had a small critical nucleation radius (22.0 nm). The large thermodynamic driving force and the high kinetic energy migration energy barrier of γ-Al7Cu4Ni and Al3Sc (V, Ni) phases led to the finer microstructure of grain. V element not only promoted the formation of Al21V2 phase containing Sc but also hindered the mutual diffusion of Al and (Sc, Ni) elements in the eutectic system via segregation at the α-Al/Al3Sc (V, Ni) interface, which improved the stability of the whole alloy. The edge nucleation of γ-Al7Cu4Ni phase upon its diffusion into a Sc-containing Al21V2 phase induced the formation of Al3Sc (V, Ni) structure, whereas the segregation of V and Ni further strengthened the alloy matrix.

INVESTIGATIONS ON THE MACHINABILITY CHARACTERISTICS OF Al–Zn(5.4)–Mg(2.4)–Cu(1.4) ALLOY COMPOSITE USING TOPSIS APPROACH

In this research, stir casting was used to create the aluminium alloy (AA7075) composite filled with 10[Formula: see text]wt.% zirconia (ZrO2) particles as reinforcement. Die sinking electric discharge machining (EDM) was used to examine the machining characteristics of the proposed composite. The machining experiments were executed in accordance with the [Formula: see text] orthogonal layout. Here, the material removal rate (MRR) and surface roughness (SR) were taken into account as the output responses, and the discharge current ([Formula: see text]), pulse on-time ([Formula: see text]), and pulse off-time ([Formula: see text]) were taken as the machining parameters. To determine the optimal parameter conditions for the output responses, the technique for order preference by similarity to ideal solution (TOPSIS) approach was applied. According to the experimental findings, the optimum settings of the parameters are determined at 15[Formula: see text]amps of ‘[Formula: see text]’, 750[Formula: see text][Formula: see text]s of ‘[Formula: see text]’ and 50[Formula: see text][Formula: see text]s of ‘[Formula: see text]’. ANOVA results stated that ‘[Formula: see text]’ has the most notable factor with a contribution of 90.85%. The interaction effect of parameters on the responses was shown by the contour plots. The confirmatory experiment was finally conducted at the optimum machining parameter settings, and it was found that the error only occurred in 8.4%.

Effect of prerolling before artificial aging on the mechanical properties of high-Zn-content Al–Zn–Mg–Cu–Sc–Zr–Mn alloy

The effect of prerolling before artificial aging on the mechanical properties of the Al–Zn–Mg–Cu–Sc–Zr–Mn alloy with 12.4 wt% Zn (Zn/Mg ratio >1.3 at.%) is studied. The alloy sheets are prepared via casting, homogenization, hot rolling, and solution treatment. The sheets are further cold rolled to reduce their thicknesses by 0%–50% before being artificially aged. Yield strength, ultimate tensile strength, and elongation are increased from 648 to 697 MPa, from 662 to 712 MPa, and from 2.2% to 4.4% by prerolling up to 30%, and prerolling again by 50% reduces both the strength and elongation. Changes in the microstructural features, such as grain morphology, dislocation density, and defect characteristics, are attributed to the variations in the strength and elongation of the alloy. Work hardening during prerolling is responsible for the increase in strength, while pore closure and shear band formation induced by prerolling either increase or decrease the elongation. Furthermore, precipitation kinetics are accelerated by applying prerolling, which facilitates a faster aging response, lesser processing time to reach the peak hardness, and better mechanical properties.

Effects of L12 precipitates containing Zr, Er, and Y on the precipitation of Al–Zn–Mg alloys at elevated temperatures

Microalloying significantly enhances the high-temperature properties of nano-precipitates through solute partitioning at elevated temperatures. In this study, we investigated the effects of L12 crystal structural precipitates containing Zr, Er, and Y influence the precipitation of Al–Zn–Mg alloys using transmission electron microscopy and atom-probe tomography. The results demonstrate that the multi-addition of Zr, Er, and Y improves both ambient and high-temperature hardness of Al–Zn–Mg alloys by increasing the number density of precipitates and preventing coarsening of L12/η-MgZn2 type nano-precipitates during over-aging period at elevated temperatures. Particularly, Y forms a thermally stable L12 precipitate through multiple additions with Zr and Er, a finding supported by atom-probe tomography, which reveals a synergistic interaction between Er and Y. The Er and Y multi-addition increases the number density of fine L12-Al3(Zr, Er, Y) precipitates, providing heterogeneous nucleation sites for η-type nano-precipitates at the interfaces between L12/η precipitate, thereby increasing the formation of fine η-type nano-precipitates during the over-aging period.

Use of third generation data for the pure elements to model the thermodynamics of binary alloy systems: Part 3 – The theoretical prediction of the Al–Si–Zn system

In a previous paper a method was developed to define Einstein temperatures for metastable phases of the elements and their relation to the so-called lattice stabilities used in the past, and also the variation of the Einstein temperature with composition to account for the composition dependence of the excess entropy. This approach was demonstrated successfully for the Al–Zn system. In this paper this approach is extended to cover the Al–Si and Si–Zn binary systems. The phase diagram for the Al–Si–Zn ternary system was then predicted from the thermodynamic description of the binary subsystems only without any ternary interaction parameters. Agreement with the experimental data is shown to be very good.

Effect of intermittent non-isothermal aging on the microstructure and properties of Al–Zn–Mg–Cu alloy

The proposition of an intermittent non-isothermal aging (IM-NIA) is an innovative approach to address the challenge of balancing the mechanical properties and corrosion resistance of Al–Zn–Mg–Cu alloys. The effects of IM-NIA on the hardness, corrosion resistance and microstructure morphology of Al–Zn–Mg–Cu alloys were investigated by hardness test, intergranular corrosion test (IGC), exfoliation corrosion test (EXCO), electrochemical corrosion test and combined with transmission electron microscopy (TEM) observation. The results showed that the hardness of the alloy was the highest at 186HV after intermittent post-tempering to 180 °C (IM-H180). The intergranular corrosion depth is the smallest, the corrosion rate is the slowest, and the exfoliation corrosion rating is EA. In addition, the alloy matrix precipitated phase has the smallest average diameter, the highest volume fraction, the strongest ability to repair the passivation film, and the strongest resistance to Cl− erosion; At the same time, the grain boundary precipitation phase is intermittent and multilinear parallel distribution, PFZ is the widest, hindering the anodic corrosion channel, slow corrosion progress and improve corrosion resistance.

Investigation of hot deformation behavior and three-roll skew rolling process for hollow stepped shaft of Al–Zn–Mg–Cu alloy

The increasing demand for high-strength lightweight hollow shafts in transportation highlights the need for advanced fabrication techniques. Al–Zn–Mg–Cu alloys, noted for their superior properties, are selected for three-roll skew rolling (TRSR). In TRSR, the material undergoes combined axial tensile and radial compressive stresses. This study evaluates the feasibility of TRSR for producing high-strength lightweight hollow stepped shafts from Al–Zn–Mg–Cu alloy. An integrated approach, including constitutive modeling, hot processing map development, and TRSR numerical simulations/experiments, is employed to optimize the TRSR forming process. The constitutive model was established based on 300°C–450 °C & 0.01–10 s−1 hot compression and 350°C–430 °C & 0.1–5 s−1 high-temperature tensile test data. The established Johnson-Cook optimization by genetic algorithms (GA-JC) model and unified viscoplastic constitutive model, accurately capture the alloy's hot deformation behavior, exhibiting minimal average absolute relative errors (AARE) of 5.431% and 5.808%, respectively. Microstructure evolution analyses shed light on the predominant softening mechanisms, emphasizing dynamic recovery (DRV) at elevated strain rates and diminishing texture intensity with escalating deformation temperatures. The composite hot processing map delineates optimal process parameters (400°C–450 °C & 0.1s−1-1s−1), facilitating informed decision-making in manufacturing practices. The validation of numerical simulations through TRSR forming experiments with initial temperature of 450 °C for the billet and axial moving speed of 10 mm/s for the chuck in affirms the feasibility of producing hollow stepped shafts from high-strength Al–Zn–Mg–Cu alloy. Close agreement was found between simulated and experimental wall thickness variations. This study enhances understanding and optimization of TRSR forming for high-strength lightweight alloys, advancing industrial manufacturing methodologies.

Optimizing corrosion behaviours of an Al–Zn–Mg–Cu alloy through cold rolling and artificial ageing

Optimizing corrosion behaviours of an Al–Zn–Mg–Cu alloy through cold rolling and artificial ageing

Plasma Spheroidization of Al–Zn–Mg–Fe–Ni Alloy Powders for Selective Laser Melting

Plasma Spheroidization of Al–Zn–Mg–Fe–Ni Alloy Powders for Selective Laser Melting

Effect of retrograssion and re-aging on microstructure and properties of Al–Zn–Mg–Cu–Zr–Er alloy

Effect of retrograssion and re-aging on microstructure and properties of Al–Zn–Mg–Cu–Zr–Er alloy