Al-Zn Alloys Research Articles

Simultaneous Improvement of Strength, Ductility and Damping Capacity of Single β-Phase Mg–Li–Al–Zn Alloys

Body-centered cubic (BCC) Mg–Li alloy can be effectively strengthened by with the addition of Al and Zn. However, adding excessive amounts result in reduced mechanical properties and damping capacity of the alloy during subsequent heat treatment and deformation. The effects of solution-hot rolling-aging on the mechanical properties and damping capacity of LAZ1333 alloy and LAZ1366 alloy were studied. The solid solution strengthening greatly increases the hardness of the alloy, but the ductility is extremely poor. The AlLi softening phase precipitated during the subsequent hot rolling and aging process greatly improves the ductility of the alloy, but the excess precipitation of in the AlLi softening phase and the solid solution of excess Zn element are not conducive to the substantial improvement of the strength and ductility of the alloy. Excessive addition of alloying elements is detrimental to the damping capacity of the alloy, but the damping capacity of the alloy can be significantly improved by depleting the number of solute atoms through subsequent ageing treatments. The UTS and FE of as-cast LAZ 1333 alloy are 111 MPa and 16.9%, respectively. The as-aged LAZ1333 alloy has the best mechanical properties and damping capacity, and the UTS and FE are increased by 65.8% and 89.3%, respectively, compared to the as-cast alloy, and the damping capacity increased from 0.011 to 0.015.

Surface tension of liquid mixtures and metal alloys. Positive and negative temperature coefficients in alloys with remarkably high surface density

The effect of temperature on the surface tension is examined in liquid alloys that combine a positive or negative temperature coefficient with gravity limitation of the surface concentration in the surface-active metal constituent. This is a restriction that is likely to occur in alloys where the metal with lower surface tension is much denser than the other component. Since there is a surface tension increase due to diminished segregation, the resultant temperature coefficient will depend on the superposition of two independent effects. Working in the framework of Butler’s thermodynamics for ideal surface phases, equations and methods of analysis are obtained to describe both effects. These developments are illustrated with alloys where the surface density is likely to attain the bulk density at certain compositions, namely the Al–Zn alloys that exhibits a negative temperature coefficient and the Sn–Bi, Ga–Bi, Ga-Pb and Cu–Pb alloys that present composition ranges with positive temperature coefficients. The specific concave down dγ/dT curves of liquid alloys are theoretically predicted. Furthermore, good estimates are obtained for systems with positive and negative temperature coefficients, except within a 50 K interval of phase transitions, or for systems showing large deviations from ideal behaviour.

Suppressing zinc dendrite growth in aqueous battery via Zn–Al alloying with spatially confined zinc reservoirs

Rechargeable aqueous zinc-ion batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrite formation and low stripping/plating coulombic efficiency when using bare Zn metal foil as anode have severely limit the battery reliability and energy density. Thus, to develop a more robust ZIB anode with lower extent of dendrite growth, Zn–Al alloy is proposed in this work. The passivating Al2O3 shell formed on the Al phase can provide two key functions; (1) selective electrochemical stripping of Zn due to electrochemically inert Al2O3, and (2) guiding the electrodeposition of Zn on the available Zn sites. The as-prepared Zn–Al alloy anode is able to outperform the bare Zn anode as bare Zn anode shows signs of short circuit after cycling. When paired with V6O13 cathode, the Zn–Al//V6O13 cell delivers enhanced rate performance and a nearly 95% capacity retention after 1000 cycles at 3 A g−1, with a specific capacity of 280 mA h g−1. The strategy demonstrated that Zn–Al alloy is suitable for aqueous zinc-ion batteries due to its low corrosion rate, low dendrite formation, low corrosion current, and high capacity retention.

Mechanism of room-temperature superplasticity in ultrafine-grained Al–Zn alloys

Superplastic deformation of polycrystalline materials is usually accommodated by diffusion-assisted grain boundary (GB) sliding at high temperatures. Lowering the temperature requirement for commercial superplastic forming enables green and cost-effective manufacturing. Recently, room-temperature (RT) superplasticity was realized in ultrafine-grained Al–Zn based alloys, but the underlying mechanism remains unclear. Here, we conducted in-situ tensile straining and post-mortem electron microscopy characterization, and atomistic density functional theory simulation to understand the RT superplasticity of an Al–15 Zn (at%) alloy. Results showed that the superplasticity is achieved by GB sliding and grain rotation, assisted by the continuous diffusion of Zn. In-situ observations showed Zn atoms diffusing from within grains to GBs, resulting in a Zn nanolayer at the GBs that acts as a solid lubricant to decrease the energy barrier of GB sliding. This research advances our understanding of diffusion-assisted deformation mechanism that is a prerequisite for the rational design of new materials with RT superplasticity.

Enhancement of Interfacial Wettability between Al-Zn Alloy Matrix and MnO2 Decorated with Ni for Effective Cathodic Protection Systems

Substrates made of steel used in coastal applications are regularly exposed to harsh salty environments; as a result, it is essential to adopt reliable strategies for preventing corrosion. Utilization of aluminum rich sacrificial anodes is an efficient anticorrosive technique owing to its high columbic amplitude, low density, inherent negative potential and galvanic economy. In this work, the electrochemical and micro-structural was characterized by catalytic effect of MnO2-Ni on anode activation. MnO2-Ni present in anode matrix results in destroyed passive alumina film and facilitates the galvanic growth on an anode. The anode exhibited active operating potential and high columbic efficiency during prolonged marine exposure studies. High anodic efficacy was performed by fine tuning composites into the metal matrix Al based alloy. The results revealed that the preferential dissolution of intermetallic particles induced effective sacrificial anode action.

Microstructural Evolution and Mechanism of Strengthening in Al-Zn/fly ash/ ZrO2 Composites Fabricated Through a Vortex

This paper describes the fabrication of aluminum-zinc (Al-Zn) alloy (AZ91E) metal matrix composites augmented with Fly Ash (FA) and zirconium dioxide (ZrO2) particulate utilizing the vortex method and a stir casting process. The researchers introduced composites with ZrO2and fly ash at varied weight % ranging from 0 to 10 with 53 μm particle sizes. The inclusion of ZrO2 particle reinforcement increased the hardness significantly, whereas the ultimate yield and tensile strengths increased somewhat. As the weight % of ZrO2 particles was increased, the permeability and density of Al-Zn alloy based composites increasing. When compared to the comparable alloy, composite densities were lower, which might be attributed to the low density of the FA. Additionally, the compressive and tensile crack properties of the composites produced were investigated. Microstructural analyses confirmed the presence of evenly dispersed FA and ZrO2 particles throughout the matrix, but an EBSD study revealed that this led to the diminished reduction. The inclusion of FA particles enhanced the material’s tensile properties and hardness including ultimate yield and tensile strengths. The strengthening mechanisms underlying the enhanced properties were discussed. At the point when ZrO2 and FA fortifications were applied, a definite tensile and yield strengths raised in contrasted with the basic compound. As revealed by the aftereffects of the examination, the grain size of the Al-Zn composite built up with FA and ZrO2 particulates is a lot of lower than the grain size of the lattice compound.

Effects of Er addition and cooling rate on the corrosion resistance of Zn-5Al alloys

Galfan (Zn-5Al-RE) coating is widely used in high-strength steel wires. The effects of cooling rate and the adulteration of erbium (Er) on the microstructure and corrosion resistance of Zn-5Al alloys were investigated in this study. The results show that the Zn-5Al alloy is made up of the primary η-Zn phase and eutectic structure at a high cooling rate. As the cooling rate decreases, the corrosion current firstly increased and then decreased due to decrease of the primary η-Zn content , the appearance and grew of α-Al phase. Moreover, the addition of Er leads to the formation of Er-containing intermetallic compounds in the Zn-5Al alloy, reducing the size of the primary η-Zn and α-Al phase, decreasing the corrosion current density, and improving the density and compactness of the corrosion product.

An investigation of microstructure and mechanical properties of as-cast Zn–22Al alloy during homogenizing and equal channel angular pressing

In this study, the effect of homogenization heat treatment and equal channel angular pressing process (ECAP) on microstructure and mechanical properties were explored in Zn–22Al alloy. It was observed that homogenization caused a significant part of the structure to transform to equiaxed grains from an initially lamellar structure. Also, with increasing time of homogenization, a homogeneous structure with no coarse phases were created. Average grain sizes of 48, 2.5, 1.2 and 1.1 μm were respectively achieved after homogenization for 4, 8, 12 and 24 h at 375 °C followed by water quenching. By removal of the lamellar structure during homogenization, improved superplastic behavior was observed. By increasing the time of homogenization, a decrease in microhardness took place which can be due to the loss of hard dendritic phases in the microstructure. On the other hand, grain size of 0.44 μm was achieved after 8 passes of ambient temperature ECAP process which was found to be quite effective in forming the ultra-fine grained (UFG) and equiaxed microstructure leading to further improvement in superplastic behavior. By increasing the number of ECAP passes, the failure elongation increased. On the other hand, the microhardness curve showed a work softening which is associated with the dynamic recovery/recrystallization of η phase after ECAP process.

Flake-like ZnAl alloy powder modified waterborne epoxy coatings with enhanced corrosion resistance

Zinc-rich epoxy coatings (ZRECs) have been widely used to protect steel against corrosion because of their excellent corrosion resistance. However, the ZRECs preparation usually used a large amount of Zn powders and organic solvents, which not only wasted resources but also produced a great quantity of volatile organic compounds (VOC). Therefore, it was necessary to develop a method which can prepare epoxy coatings with low Zn content, great corrosion resistance and green environmental protection. In this paper, three different flake metal powders (Zn, ZnAl alloy and ZnAlMg alloy) were used to replace spherical Zn powders to develop environmentally friendly coatings with low pigment content. The coatings were evaluated by salt spray test and electrochemical test. The results show that the use of flake metal powders instead of spherical zinc pigments can enhance the electrical connection between metal particles, prolong the path of corrosive medium infiltration into the coatings, enhance the physical shielding effect of the coatings, and reduce the pigment content by one third. Among them, the ZnAl coatings displayed the best anti-corrosion performance resisting salt fog corrosion for 28 days. In addition, the experimental results show that the self-healing ability of the coatings also plays an important role in the immersion middle and late stages. In short, the waterborne epoxy ZnAl coatings are suitable for large-scale application in harsh environments.

Corrosion Resistance Analysis of Al-Cu, Al-Zn and Al-Cu-Zn Alloys

Anticipating an alloy's corrosion resistance is essential to avoid product failure and reduce costs. Research and analyze the corrosion resistance of Al-Cu, Al-Zn and Al-Cu-Zn alloys based on the analytical balance of the elements according to weight, thermodynamic, metallurgical rules on metal alloys, kinetic and other properties. The purpose of this study is to determine the corrosion resistance of Al-5-wt% Cu, Al-5-wt% Zn and Al-5-wt% Cu-5-wt% Zn alloys based on the analytical calculation. Based on the analytical calculation results, the Al-Zn-Cu alloy has the best corrosion resistance with a corrosion rate of 0.4375 mmpy. Next is the Al-Cu alloy with a corrosion rate of 0.4634 mmpy. While Al-Zn alloy has the lowest strength with a corrosion rate of 0.4828 mmpy. Based on standard EMF potential values for these three alloys. Al-Zn alloys are most active with an value of-1.61 V, followed by Al-Zn-Cu alloys with an value of - 1.60 V, and the noblest Al-Cu alloy has the most positive value of-1.56 V. Faraday's law to get corrosion rates of the anode and cathode materials. In the third reaction, the exothermic alloy has a positive value of so the exothermic reaction occurs.

Hydroxyapatite Effect on the Corrosion Rate of AMC Al-Zn by Powder Metallurgy

Al-Zn-based AMC is a light metal, with low density, excellent mechanical and mechanical properties, suitable for use in automotive, electrical, general-purpose electronics, machinery and equipment. However, the development of this alloy is limited by its low hardness and low corrosion resistance, which limits its use in many applications. This corrosion process can cause fitting corrosion and can damage the passive oxide layer that protects the metal from corrosion. This study aimed to increase the corrosion resistance of AMC Al-Zn by adding hydroxyapatite ceramic reinforcement from snail shells in a corrosive medium of 3.5% NaCl solution. The HAp is used as an AMC amplifier. AMC uses Al-Zn alloys with a ratio of 90% to 10% by mass. The variation of HAp enhancer used was 10, 15, 20, 30 and 40% by weight. This AMC was produced by powder metallurgy using 250 KPa compression for 20 min with sintering at 550°C for 2 h followed by slow cooling. The characterization of Al-Zn-based AMCs was performed by electrodynamic polarization testing in 3.5% NaCl solution. From the experimental results, the addition of HAp snail waste at a concentration of 20% by weight with matrix composition Al90-Zn10 is an AMC preparation with optimal corrosion resistance. The corrosion rate of Al90-Zn10/20HAp is 0.01 mmpy, while the corrosion rate of Al90-Zn10/0HAp is 1.15 mmpy. The addition of HAp up to 20% by weight showed the highest micro-hardness (117.90 Hv) while the smallest micro-hardness occurred at AMC Al90-Zn10/0HAp (87.57 Hv). The HAp material could very well be used as an AMC-reinforced biomaterial for biomedical applications.

A synergistic effect on enriching the Mg–Al–Zn alloy-based hybrid composite properties

Mg–Al–Zn alloys are widely preferred in many applications by considering their excellent properties of high stiffness-to-weight ratio, lightweight, high strength-to-weight ratio, low density, castability, high-temperature mechanical properties, machinability, high corrosion resistance, and great damping. Improving the properties of such alloys is challenging due to their hexagonal crystal structure and other alloying limitations. This study aims to synthesize Mg–Al–Zn alloy by incorporating the alloying elements 8.3 wt% Al, 0.35 wt% Zn on pure magnesium (Control specimen). Then synthesize Mg–Al–Zn/BN/B4C hybrid composite by reinforcing B4C at three weight proportions (3 wt%, 6 wt%, 9 wt%) along with constant solid lubricant BN (3 wt%) through a stir casting process. The hybrid composite samples were characterized and compared with the performances of the control specimen. The results reveal that 9 wt% B4C reinforced samples outperformed through recording the improvement of tensile strength by 28.94%, compressive strength by 37.89%, yield strength by 74.63%, and hardness by 14.91% than the control specimen. Apart from this, it has reduced the corrosion area (37.81%) and noticed negligible changes in density (increased by 0.03%) and porosity (decreased by 0.01%) than the control specimen. The samples were characterized using SEM, XRD, and EDAX apparatus.

Deformation behavior at cryogenic temperature in extruded Mg–Al–Zn alloy

ABSTRACT The effect of grain size on tensile deformation behaviors at room- and cryogenic-temperatures was examined using extruded Mg–Al–Zn (AZ31) alloys with different average grain sizes of 3.7, 14.0, and 38.7 μm. The mechanical properties were influenced by the grain size as well as the testing temperature. Strength increased with a finer grained structure and a lower testing temperature. Regarding the elongation-to-failure in tension, all the alloys tested at cryogenic-temperature exhibited about half the values of those at room-temperature. Deformed microstructural observations revealed that deformation twins formed in the alloys with coarse- and meso-grained structures, but decreased with grain refinement. The reduction of twin formation at both room- and cryogenic-temperatures is due to enhancement of grain boundary plasticity. Contrary to our expectation, it is interesting to note that grain boundary compatibility contributes to activation of non-basal dislocation slips, irrespective of testing temperatures. In addition, dislocation slips lead to occurrence of strain hardening after yielding even at 77 K.

Anodic behavior of gallium doped Zn55Al alloy in acid, neutral and alkaline environments

The paper presents results of potentiostatical and potentiodynamical research of anode behaviour of gallium-doped Zn55Al alloy in acid, neutral and alkaline environments of electrolytes HCl, NaCl and NaOH, at various pH values. Gallium additives (0.01-1.0 wt%) lead to displacement of corrosion electrochemical potential, pitting formation and repassivity to positive values. The results indicate a decrease in the corrosion rate of gallium doped alloys by 2-3 times compared to the base alloy. Such dependence is observed in all investigated corrosion environments.

Behavior of localized strain under hot compression of cast specimen from Mg–Al–Zn alloy

Axisymmetric hot compression experiments of Mg–Al–Zn specimens in intervals of temperature 250–450 °С and deformation rate (10-3-5)·10–1 s–1 were carried out. Structure formation was studied by optical microscopy. Macroscopically localized strain of cylindrical specimens depending on temperature, strain rates and initial grain size (400 μm and 1400 μm) are investigated. Localized strain diagrams for different initial grain size can be used for development and optimization of hot processing technology parameters are plotting. It is shown that increase of the grain size direct to strain localization increment tendency.

Scalable production of hydrogen evolution corrosion resistant Zn-Al alloy anode for electrolytic MnO2/Zn batteries

Electrolytic MnO2/Zn battery has attracted significant attention for large-scale energy storage due to its advantages of high energy density and low cost. However, the acidic electrolyte used to maintain the Mn2+/MnO2 chemistry causes severe and irreversible hydrogen evolution corrosion (HEC) on the Zn anode. Herein, we present a scalable, metallurgical Al alloying approach to mitigate the HEC of Zn and prolong the battery's cycle life. Through various in situ and ex situ characterizations, it is demonstrated that the HEC on Zn-Al alloy electrode is effectively inhibited in the acidic electrolyte with and without the electric field effect. The outstanding anti-HEC capability of the Zn-Al alloy anode enables the electrolytic MnO2/Zn-Al battery with a high discharge voltage of more than 1.9 V at 1 C, a more stable cycle performance, and an enhanced cycle life comparing with the MnO2/Zn battery. Meanwhile, the experimental and COMSOL simulation results also reveal that the preferential but with slow corrosion speed of Al matrix in Zn-Al alloy is the key factor to improve the anti-HEC capability. This work exhibits the practicality of alloying strategy to produce scalable and robust Zn alloy anodes for the electrolytic MnO2/Zn battery in the large-scale energy storage field.

Ultra strength-ductility synergy in the Mg-Al-Zn alloy via densely dispersed multi-scale {10[formula omitted]} tension twins

Enhancing the strength and ductility of widely used Mg–Al–Zn alloys is an urgent requirement for Mg alloy load-bearing components. Ultra-fine grains and a large amount of β-Mg17Al12 precipitates improve their strength but reduce ductility. This work developed a commercial AZ80 alloy with the ultimate tensile strength (UTS) of 512 MPa and elongation to failure (EF) of 19.8% using a combination of extrusion and multi-directional forging processes, which has superior strength-ductility synergy among the reported AZ80 alloys and reaches the level of wrought Mg-RE alloys. The excellent mechanical properties are attributed to the formation of densely dispersed multi-scale {1012‾} tension twins. The introduction of ultra-fine {1012‾} twins reduces the mean free path of dislocations leading to a faster dislocation accumulation, which improves the work hardening ability of the alloy. This work provides a new insight into the development of low-cost Mg alloy forging billets with high strength and ductility.

Bimetallic Rechargeable Al/Zn Hybrid Aqueous Batteries Based on Al-Zn Alloys with Composite Electrolytes.

Aluminum is abundant and exhibits a high theoretical capacity and volumetric energy density. Additionally, the high safety of aqueous aluminum-ion batteries makes them strong candidates for large-scale energystorage systems. However, the frequent collapse of the cathode material and passive oxide film results in the difficult development of aqueous aluminum-ion batteries. This work provides a novel battery system, namely, Al-Zn/Al(OTF)3 +HOTF+Zn(OTF)2 /Alx Zny MnO2 ·nH2 O, with a mixed electrolyte. The cathode applies MnO topology transformation to ensure that the cathode forms Alx MnO2 ·nH2 O. Topology transformation alters the structure of the cathode material so that Zn2+ can be intercalated into the Alx MnO2 ·nH2 O spinel structure to provide support for the material structure. Regarding the anode, Zn2+ in the electrolyte is deposited onto Al of the anode to produce a regional Al-Zn alloy. Zn2+ is reduced to Zn metal during discharging, which adds a platform for secondary discharge beneficial for battery capacity enhancement. This system can provide a 1.6V discharge platform, while the first cycle discharge can reach 554 mAhg-1 , thereby maintaining a high capacity of 313 mAhg-1 after 100 cycles. This study provides a new idea for the further development of aqueous aluminum-ion batteries (AAIBs).

(Digital Presentation) Corrosion Resistance of 55%Al-Zn Alloy Fabricated By Ball Milling and Spark Plasma Sintering

Hot-dip 55mass%Al-Zn coated steels show good corrosion resistance because the 55%Al-Zn alloy coating layer acts as a sacrificial anode and protects the steel substrate from atmospheric corrosion.1 The balance between sacrificial behavior and dissolution resistance is important for improving the corrosion protection ability of the Al-Zn coating. In this study, 55%Al-Zn alloy was fabricated by ball milling and spark plasma sintering, and the effect of microstructure on the dissolution behavior of the 55%Al-Zn alloy was investigated. The 55%Al-Zn alloy specimen was fabricated by ball milling of Al and Zn powders and subsequent spark plasma sintering. The coating layer on the hot-dip 55%Al-Zn coated steel was used to compare the dissolution behavior. The dissolution behavior of 55%Al-Zn alloys was analyzed by galvanic current measurements and polarization measurements in a diluted synthetic seawater. In the sintered 55%Al-Zn alloy, Zn-rich phases with diameter less than 500 nm were dispersed in the Al matrix. The galvanic current measurements between the sintered 55%Al-Zn alloy and the steel substrate showed that the sintered 55%Al-Zn alloy acted as a sacrificial anode. In the galvanostatic polarization measurements, the potential of the sintered 55%Al-Zn alloy remained lower than that of the hot-dip 55%Al-Zn coating layer.Reference: S. Tokuda, I. Muto, Y. Sugawara, M. Takahashi, M. Matsumoto, and N. Hara, Corros. Sci., 129, 126–135 (2017).

Design of heat-resistant Al–Mg –Zn–Cu–Ni quinary alloy: Controlling intermetallic phases and mechanical performance at elevated temperature

Owing to good formability, wrought Al alloys are used in a wide range of industries, including turbochargers in automobile engines. The development of Al alloys with increased high-temperature strength is necessary to improve the fuel efficiency of engines. In this study, a modified heat-resistant Al–Mg–Zn–Cu–Ni quinary alloy with superior high-temperature strength and creep rupture life at 200 °C (potential temperature in service for compressor radial impellers) was designed. The thermodynamic assessments provided a modified alloy composition of Al–5Mg–3.5Zn–2Cu–2Ni (at %) exhibiting α-Al phase in equilibrium with T-Al6Mg11Zn11 and Al3(Ni, Cu)2 phases at elevated temperatures. The experimental alloy showed granular T and Al3(Ni, Cu)2 phases often located on grain boundaries in the α-Al matrix, although the undissolved Al3Ni phase (formed in solidification) locally remained. Apart from the T phase, the η-Zn2Mg phase containing Cu element preferentially precipitated on grain boundaries. A large number of fine precipitates were dispersed homogeneously in the grain interior after the aging at 200 °C or 300 °C. Compared to the base alloy with a ternary composition of Al–5Mg–3.5Zn (at %) and conventional Al alloys, the designed quinary alloy (pre-aged at 200 °C for 10 h) showed a high strength at elevated temperatures above 200 °C. The creep-rupture life at 200 °C/105 MPa was remarkably extended to 665 h by the addition of Cu and Ni elements into the base ternary alloy. The rupture life was more than ten times longer than one (57 h) of the ternary alloys. The alloy modification based on the thermodynamic calculations provides an effective approach for designing lightweight Al alloys with superior high-temperature strength and creep rupture life.