Al-rich Phase Research Articles

Intense alteration on early Mars revealed by high-aluminum rocks at Jezero crater

The NASA Perseverance rover discovered light-toned float rocks scattered across the surface of Jezero crater that are particularly rich in alumina ( ~ 35 wt% Al2O3) and depleted in other major elements (except silica). These unique float rocks have heterogeneous mineralogy ranging from kaolinite/halloysite-bearing in hydrated samples, to spinel-bearing in dehydrated samples also containing a dehydrated Al-rich phase. Here we describe SuperCam and Mastcam-Z observations of the float rocks, including the first in situ identification of kaolinite or halloysite on another planet, and dehydrated phases including spinel and apparent partially dehydroxylated kaolinite. The presence of spinel in these samples is likely detrital in origin, surviving kaolinitization, pointing to an ultramafic origin. However, the association of low hydration with increased Al2O3 abundances suggests heating-induced dehydration which could have occurred during the lithification or impact excavation of these rocks. Given the orbital context of kaolinite-bearing megabreccia in the Jezero crater rim, we propose an origin for these rocks involving intense aqueous alteration of the parent material, followed by dehydration/lithification potentially through impact processes, and dispersion into Jezero crater through flood or impact-related processes.

Investigation of phase transformation and mechanical properties of silicon addition on AlCrFeMnNi high entropy alloys

Abstract This paper examines the impact of silicon in the AlCrFeMnNi high-entropy alloy system, focusing on both its microstructural and mechanical properties. Alloys with varying silicon content (x = 0, 0.3, 0.6, 0.9 atomic ratio) were synthesized using vacuum arc melting. The phase formation of these high-entropy alloys was analyzed using X-ray diffraction to comprehend the alloying process behaviour. The findings revealed that the solidification of the AlCrFeMnNi alloy occurred in dendritically, with dendrite cores containing Cr, Fe, and Ni, while interdendritic regions were enriched in Al and Ni after adding Silicon. Increasing the silicon content from 0 to 0.9 led to significant improvements in microhardness and wear resistance. This improvement is attributed to the reinforcement of grain boundaries provided by silicon. The formation of an Al and Ni rich B2 phase is crucial in resisting dislocation motion and preventing further deformation. Additionally, the addition of silicon led to improved corrosion resistance, as demonstrated by potentiodynamic polarization measurements. However, a trade-off was observed between compressive strength and ductility: compressive strength increased with higher silicon concentrations, but at the expense of ductility.

Improved wear and corrosion resistance of magnesium AZ80 alloy prepared by laser surface remelting

Laser surface remelting (LSR) is a laser-based surface treatment method. In the LSR process, microstructural defects such as cracks and porosity are suppressed in addition to grain refinement, and the mechanical properties are improved. The present research investigated the effects of LSR parameters on the microstructure, wear, and corrosion behavior of Mg AZ80 alloy. The results showed that in LSR, the coarse-grained (29.8 μm) structure of AZ80 was transformed into a fine-grained structure (3.1 μm) with no microstructural defects. The evaporation of Mg during LSR and the formation of Al-rich and Mg-poor phases are the most important challenges in the surface treatment of AZ80. This limitation was solved by optimizing the LSR parameters, which included a gas flow rate of 2 L min−1, pulse duration of 3 ms, scanning speed of 3 mm s−1, pulse frequency of 8 Hz, and heat input of 64 J mm−1. The prevention of Mg evaporation was associated with the elimination of porosity and cracks, reducing of the solidification range, and uniform distribution of β-Mg17Al12 precipitation phases in α-Mg refined grains. The tribological behavior of the laser-treated region showed that the COF, depth of the wear scar, wear rate, and wear volume loss were reduced by 18%, 48%, 37%, and 66%, respectively, compared to AZ80. This result is attributed to the refinement of α-Mg grains and the uniform distribution of β-Mg17Al12 in the laser-treated region. The results of the polarization curves of the corrosion test in 3.5 wt% NaCl solution showed that the optimal laser-treated region with the lowest corrosion current density (34.68 × 10−6 μA.cm−2) and highest self-corrosion potential (1.425 V) exhibited the highest corrosion resistance. A slight change in the breakdown potential current slope in the laser-treated region indicates the formation of a protective film on the surface after the completion of LSR, which increases corrosion resistance.

Design of explosively welded Fe–Al multilayer laminated composite pipes: A critical microscopy analysis of stand-off distance and post-weld heat treatment effects on interface properties

This study examined the microstructure and mechanical properties of explosively welded (EXW) Fe–Al multilayer laminated composite pipes, specifically SS321/AA1050/AA5083, with varying stand-off distances (SD) and post-weld heat treatments (PWHT). Findings revealed that higher collision forces at higher-SD produced a wavy interface with finer grains at the AA1050/AA5083 interface. In contrast, lower-SD yielded a smooth, flat interface. At the SS321/AA1050 interface, collision energy resulted in the formation of an uneven composite reaction layer comprising multiple intermetallics. Analysis of the SS321/AA1050 interface revealed that an increase in the PWHT temperature results in diffusion toward the reaction layer, transforming the unevenly Al-rich and Fe-rich phases into a uniform Al85(Fe,Cr,Ni)15 solid solution. The increase in the fraction of this phase made the reaction layer more brittle. At the AA1050/AA5083 interface, PWHT at higher temperatures caused a significant hardness decline extending further from the interface in samples with higher-SD. On the SS321 side of the laminated composite, higher SD resulted in higher kernel average misorientation (KAM) and increased hardness. Despite a decrease in hardness after PWHT at 350 °C, the hardness gradient from the matrix to the interface in laminates with higher SD remained relatively unaffected, whereas the lower SD counterparts experienced a noticeable stress relief.

Microstructure and mechanical properties of CP780 steel - 7075 aluminum alloy laser welded joint assisted by rotating magnetic field

Abstract This study uses a rotating magnetic field for laser welding on 1 mm thick CP780 high-strength steel and 1.5 mm thick 7075 aluminum alloy. The effects of different welding parameters (B = 0 mT, B = 65 mT with V = 0°/s, B = 65 mT with V = 10°/s) on the morphology, microstructure, and tensile properties of welded joints are analyzed. At B = 0 mT, the weld shape is V-shaped, with the intermetallic compounds primarily consisting of needle-like brittle Al-rich (Fe, Si)Al2 phase and fewer granular ductile Fe-rich (Fe, Si)Al phase, resulting in poor mechanical properties. With the application of the rotating magnetic field, the laser energy becomes more concentrated, forming a ‘T’ shape weld. The rotating magnetic field (B = 65 mT with V = 10°/s) generates a constantly changing Lorentz force, promoting molten pool flow and enhancing Fe diffusion within the weld. This process reduces needle-like brittle Al-rich (Fe, Si)Al2 phase and increases granular ductile Fe-rich (Fe, Si)Al phase. It also accelerates the weld cooling rate and inhibits the reaction time and grain growth of intermetallic compounds, thereby reducing the thickness and content of the intermediate transition layer and significantly improving mechanical properties. A comprehensive comparison shows that the best mechanical properties are achieved at B = 65 mT with V = 10°/s. This study offers new insights and a theoretical foundation for achieving cost-effective, high-performance welded joints in advanced high-strength steel and high-strength aluminum alloy for automobiles, thereby facilitating lightweight vehicle development.

Enhancement of copper mobilization using acidic AlCl3 − rich lixiviant

Copper (Cu) extraction from low-grade ores is limited by the formation of secondary minerals that can passivate the surfaces of Cu-sulphide minerals in these ores. Hence, a novel approach utilizing AlCl3 as a lixiviant was developed to modify coupled dissolution-reprecipitation processes at the mineral interface. The formation of Al-rich phases instead of Fe-hydroxysulphates enhanced Cu extraction through combined ferric-iron and proton-promoted dissolution. AlCl3 accelerated chalcopyrite and bornite dissolution by forming soluble intermediate Cu-phases (e.g., covellite) at consistently high Eh (550–650 mV) and acidity due to the Lewis acid property of AlCl3. X-ray diffraction analysis revealed that Na-bearing jarosite [(K0.61Na0.41)Fe3(SO4)2(OH)] and sideronatrite [Na2Fe(SO4)2(OH)(H2O)] formation in lixiviants without AlCl3 decreased Fe3+(aq) availability for Cu-sulphide minerals dissolution. In contrast, significant amounts of AlSO4+(aq) formed in the AlCl3-rich lixiviant at pH 1–3, which reduced the sulphate activity and decreased the saturation state of the Fe-hydroxysulphates. Further, AlCl3 promoted the formation of amorphous, porous Al-rich phases, facilitating quick Fe diffusion through the passivating layer and improving Cu recovery compared to lixiviants containing CaCl2, NaCl, or acid-only.

Comparison of diffusion coatings resistance on ferritic and austenitic-stainless steels at 650 °C in steam oxidation

Iron-aluminide coatings were deposited on T24, P92 and Incoloy 800HT (IN-800HT) by pack-cementation and by a water-based slurry. According to the differences in heat treatments between the two processes, Al-rich phases, i.e. Fe4Al13 and Fe2Al5 were obtained by pack cementation and only B2-(Fe, Ni)Al by slurry. Vertical or horizontal cracks were present on certain coatings, the former being due to the coefficient of thermal expansion (CTE) mismatch with the substrate while the latter were related to the brittleness of the Al-rich phases. The oxidation behaviour of uncoated and coated substrates was studied at 650 °C up to 1000 h under a low steam flow rate (1.07 × 10−5 m/s). The aluminide coatings were very protective on the low Cr substrates (i.e. T24 and P92) because of the formation of a very thin oxide scale compared to the non-protective thick layers of Fe3O4 and Fe2O3 that grew on both uncoated substrates. In contrast, none of the coatings significantly improved the oxidation resistance of the IN-800HT steel despite the growth of a thin oxide layer made of (Fe, Cr)2O3 and (Fe, Cr)3O4 at 650 °C.

Alumina solubility in periclase determined to lower mantle conditions and implications for ferropericlase inclusions in diamonds

A series of high-pressure multi-anvil experiments were conducted in the MgO-Al2O3 system between 15 and 50 GPa and at temperatures up to 2623 K, to determine the solubility of Al2O3 in periclase in the stability fields of coexisting spinel, corundum, the Mg2Al2O5 modified ludwigite phase, the MgAl2O4 calcium ferrite phase, and the MgAl2O4 calcium titanate phase. The Al2O3 solubility in periclase is strongly temperature-dependent over the conditions investigated. Conversely, periclase Al2O3 solubility exhibits a negative relationship with pressure. Experiments with up to 40 mol.% FeO in ferropericlase show Al2O3 solubilities that are near identical to those of periclase, within experimental uncertainties. A simple thermodynamic model incorporating significant literature on ambient pressure measurements is able to describe periclase Al2O3 solubility up to 40 GPa. This model is used to investigate the Al2O3 contents of ferropericlase inclusions observed in natural diamonds, which vary up to 0.35 mol. %. Pressure–temperature curves along which particular inclusions formed can be produced if equilibrium can be assumed with Al-bearing minerals found in the same diamond. Alternatively, the maximum possible Al2O3 content in ferropericlase can be determined for a certain pressure–temperature profile and inclusions with Al2O3 contents that exceed this curve can be excluded from those conditions. To obtain such solubility curves, calculations are performed for periclase coexisting with the Al-rich phases spinel, garnet, bridgmanite and the MgAl2O4 calcium ferrite phase. The calculations indicate that periclase, and by inference ferropericlase, Al2O3-contents cannot be greater than 0.5 mol.% under present day adiabatic mantle temperatures and go through a minimum at mantle transition zone conditions. This excludes a number of Al-rich ferropericlase inclusions found in natural diamonds from being formed in the transition zone, unless temperatures were super-adiabatic. This subset of inclusions likely formed either at the base of the upper mantle or the top of the lower mantle, but must have formed at near adiabatic temperatures. The majority of ferropericlase inclusions have Al2O3 contents that would be consistent with formation in the transition zone at near slab temperatures, but could still have been formed at higher temperatures if Al2O3 activities were low.

An improved preparation method of core-shell Al@Sn-Bi microspheres and its microstructure formation mechanism

This paper presents an improved method for achieving controllable preparation of the composition and size of the monotectic alloy core-shell structure microspheres. This advancement is expected to enhance the commercial application of monotectic alloy core-shell structure microspheres. By installing a heating device at the top of the drop tube in the pulsated orifice ejection method setup, we achieved in-situ heat treatment of falling droplets, resulting in the successful preparation of Al45(Sn42Bi58)55 core-shell structure microspheres. Furthermore, we investigated the formation mechanism of the Al@Sn-Bi core-shell structure. Nine sets of Al-Sn-Bi microspheres with varying in-situ heat treatment temperatures were prepared. Analysis via X-ray diffraction and transmission electron microscopy revealed that the microspheres consisted of Al-rich, Sn-rich, and Bi-rich phases, without any intermetallic compounds. Scanning electron microscopy results indicated that as the in-situ heat treatment temperature increased, the structure of the Al-Sn-Bi microspheres transitioned from irregular to regular core-shell configurations. This suggests that higher heat treatment temperatures prolong liquid phase separation time, leading to increased repetition of Marangoni motion within the droplet, Ostwald ripening of the minor phase droplets, and Soret effect of the matrix phase. However, at temperatures exceeding 700 °C, the solidification rate of alloy droplets decreased, causing the Al-rich phase core to deviate from the center and form a crescent structure due to Stokes motion.

Study on the structure and corrosion behavior of hot-dipped Zn–6Al–3Mg alloy coating in chlorine-containing environment

In this study, the microstructure and corrosion behavior of hot-dipped Zn–6Al–3Mg alloy coating in Cl-containing environment were studied. The results show that there are primary Zn phase, Al-rich phase and ternary eutectic phase in the coating. Electrochemical corrosion occurs due to the formation of micro-electric couples between dendrites and ternary eutectic. The corrosion process can be divided into four stages, including the dissolution of the oxide layer, the corrosion of the coating microstructure, the covering of the corrosion products and the formation of the stable corrosion product layer. In addition, electrochemical tests demonstrated that the active areas on the coating gradually decrease upon extending the corrosion time. The corrosion products protect the coating and improve its corrosion resistance.

Corrosion behavior of erbium modified Zn-11Al-3Mg cast alloy in stagnant 3.5 wt% NaCl solution

Zn-11Al and Zn-11Al-3Mg-xEr (x=0, 0.05, 0.1, 0.5) alloys were prepared, and the microstructures and corrosion resistance of the alloys were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and electrochemical methods. The results show that the primary Al-rich phase in Zn-11Al alloys is corroded as the main anode. The electronegativity of the primary Al phase in Zn-11Al-3Mg alloys is higher than the primary MgZn2 phase, and the electronegativity of Al-rich and Mg2Zn11 phases is higher than that of the η-Zn phase in ternary eutectic structure. The primary Al-rich phase and Mg2Zn11 phases in the alloy are corroded as the main anodes. On the other hand, the erbium (Er) reacts with Al to form the AlEr phase, and the AlEr phase has a significant refining and homogenizing effect on the primary Al-rich phase in the Zn-11Al-3Mg alloy. When the content of Er is 0.05%, the primary Al phase transforms into fine discontinuous cellular structure. However, the increase of Er addition promotes the growth of primary Al-rich phase and the reduction of ternary eutectic, which weakens the corrosion resistance of the alloy.

Study of the role of aluminium and corrosion mechanism in galvalume coating in the marine atmospheric environment

PurposeThis study aims to investigate the role of aluminium (Al) in marine environment and the corrosion mechanism of galvalume coatings by conducting accelerated experiments and data analysis.Design/methodology/approachSamples were subjected to accelerated corrosion for 136 days via salt spray tests to simulate the natural conditions of marine environment and consequently accelerate the experiments. Subsequently, the samples were examined using various test methods, such as EDS, scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS), and the obtained data were analysed.FindingsGalvalume coatings comprised interdigitated zinc (Zn)-rich and dendritic Al-rich phases. Corrosion was observed to begin with a Zn-rich phase. The primary components of the corrosion product film were Al2O3 and Zn5(OH)8Cl2·H2O. It was confirmed that the role of Al was to form a dense protective film, thereby successfully blocking the entry of corrosive media and protecting the iron substrate.Originality/valueThis study provides a clearer understanding of the corrosion mechanism and kinetics of galvalume coatings in a simulated marine environment. In addition, the role of Al, which is rarely mentioned in the literature, was investigated.

A method for preparing alloy coating on the aluminum alloy substrate via laser cladding technology to prevent the galvanic corrosion of TC4/5083 couple

The Cu-Ni-Cr alloy coating was prepared on 5083 aluminum alloy substrate using laser cladding technology. The microstructure of the coating and its galvanic corrosion resistance in contact with TC4 alloy were studied. The results indicate that the Cu-Ni-Cr alloy coating primarily consists of Al-rich dendrite phase and Cu-rich matrix phase. The shear strength of the Cu-Ni-Cr alloy coating is 154.68 MPa, which is greater than that of the aluminum alloy substrate. The galvanic current density of the TC4/Cu-Ni-Cr couple is 0.05 μA·cm−2. The neutral salt spray corrosion test results demonstrate that the Cu-Ni-Cr alloy coating exhibits excellent resistance to galvanic corrosion. The coating can attenuate the galvanic corrosion effect when it is in contact with the TC4 titanium alloy, offering new solutions to address the galvanic corrosion challenges between titanium alloy and aluminum alloy in marine environments.

Investigating the microstructure-property relationship in Mg matrix composites reinforced by particles of different sizes using experiments combined with finite element simulation

In this study, Ti particles (size of 45, 38, 15, and 5 μm) with a mass fraction of 5% reinforced the Mg-9Al-1Zn (AZ91) magnesium matrix composites are fabricated via spark plasma sintering method. Microstructure observation reveals the interfacial zone is composed of Mg17Al12 and Al-rich phase products. Mechanical testing demonstrates that the elongation of the AZ91-Ti (15 μm) composite reaches the peak value of 21.8%, the ultimate tensile strength can be maintained at 211 MPa, and the optimal elastic modulus is up to 47.85 GPa. The composites maintain high strength mainly through heterogeneous deformation induced (HDI) strengthening and thermal mismatch strengthening. From finite element simulation analysis, the relative small size of Ti particles can restrain strain concentration and facilitate stress conduction, making the strain and stress distributing uniformly. Ti particles with appropriate size can enhance the work hardening capacity, leading the AZ91-Ti composite to possess excellent comprehensive mechanical performance.

Aluminide diffusion coatings for improving the pesting behavior of refractory metals

Refractory metal based alloys show great potential as structural materials for high-temperature applications due to their high melting points, but they are prone to catastrophic oxidation at around ▪. The effectiveness of aluminium diffusion coatings on the oxidation resistance of pure molybdenum, niobium, tantalum, and tungsten was investigated. Homogeneous diffusion layers of Al-rich intermetallic phases were formed on all four refractory metals after pack cementation. Thermodynamic calculations and experimental assessments (e.g., of the activator) determined the most suitable conditions for the pack cementations. Subsequent thermogravimetric analysis of the uncoated and coated samples at ▪ and ▪ for up to ▪ in dry synthetic air was used to determine the protective effect of the coatings and investigate the underlying oxidation mechanisms. Optical and electron microscopy, EPMA, XRD and Raman spectroscopy were used to investigate the diffusion layers and the oxide scales. For two refractory metals (Mo and Ta) the aluminization resulted in an improved oxidation behavior and a substantially decreased oxide growth rate compared to uncoated substrates.

Microstructure evolution and cyclic oxidation performance of Cr2AlC as active diffusion barrier for NiCrAlY coating on TiAl alloy

Cr2AlC diffusion barrier was prepared between NiCrAlY coating and TiAl alloy. Long-term cyclic oxidation was conducted at 900 °C in air for 1000 cycles(h). Cr2AlC and transformed Cr7C3, α-Cr and TiC had significant blocking effects on Ti diffusion. So, the Al-rich phase in the NiCrAlY coatings was NiAl rather than Ni2TiAl, which inhibited the generation of TiO2 and avoided the presence of α-Cr in the Al2O3 scales. As a result, the stability and spalling resistance of the Al2O3 scales were enhanced.

Experimental and numerical analysis of intermetallics in Al–Mg friction stir welds

In this research work, it was aimed to analyse the thermal behaviour during FSW in order to understand the diffusion behaviour of Al (AA6061)-Mg (AZ31B) dissimilar joints. Three heat input levels at different weld pitch ratios (WPR) of 0.087, 0.068 and 0.051 are accounted for the analysis. Finite element modelling (FEM) is employed to predict temperature evolutions. From the FEM results and fundamental diffusion equations, the intermetallic thickness and the diffusion behaviour between the Al and Mg material were analyzed and found that the Al-rich intermetallic phases Al3Mg2 grow faster and wider than the Mg-rich phase Al12Mg17. Tensile test demonstrates that a lower welding pitch ratio (WPR) leads to the formation of thicker intermetallic layers, resulting in reduced tensile strength and joint efficiency. In contrast, a higher WPR (0.087) minimizes intermetallic thickness, yielding superior tensile properties (138mpa). Microhardness measurements at the stir zone reveal a broad range from 70 to 164 HV, signifying mechanical heterogeneity. Microstructural reveals that a complex interplay between Al and Mg materials, resulting in fine equiaxed grains, intermetallic compounds, and distinct flow patterns in the stir zone.

Effect of Pt Addition on the Oxidation and Corrosion Resistance of Al0.25CoCrFeNi High-Entropy Alloy

The effect of minor platinum alloying on the microstructure, phase composition, oxidation and corrosion resistance of Al0.25CoCrFeNi high-entropy alloy (HEA) has been studied. It was observed that Pt does not segregate as a separate phase, but it is incorporated into the fcc solid solution. High-temperature oxidation of the as-cast Al0.25CoCrFeNi and Al0.25CoCrFeNiPt0.1 high-entropy alloys was carried out in a muffle furnace under isothermal conditions at 900 °C for 0–50 h (weighing was carried out every 10 h) in air atmosphere. The specific weight gain decreased from 0.58 mg/cm2 for Al0.25CoCrFeNi to 0.31 mg/cm2 for the platinum-doped Al0.25CoCrFeNiPt0.1 sample. It was determined that Pt triggers the formation of an interlayer Al-rich oxide phase between the outer Cr-rich oxide layer and the interior of the alloy, significantly reducing the oxidation rate of Al0.25CoCrFeNiPt0.1 HEA. Electrochemical tests in 0.5 M H2SO4 solution demonstrated passive behavior with anodic control of the process.

Oxidation protection of TNM alloys with Al-rich γ-TiAl-based coatings

The request to reduce carbon emissions as well as fuel consumptions of modern aerospace and aviation mobility, heavily motivated the development of lighter and more durable high temperature materials. γ-TiAl bulk materials meet many of these requirements due to their unique properties, such as low density, high strength or excellent creep resistance. However, improving their oxidation resistance above 750 °C is still challenging, especially without deteriorating other material properties. Recently, we showed that magnetron sputtered Al-rich γ-TiAl coatings are ideal candidates for well-established TNM bulk alloys (Ti-43.5Al-4Nb-1Mo-0.1B, in at%) to increase their oxidation resistance and to block oxygen inward diffusion. Within this study, we present detailed microstructural investigations of the appearing phase transformations and morphological changes in the coating due to ambient-air-exposure at 850 °C for up to 1000 h. These show that only a 4-µm-thin, well-adhering α-Al2O3-based thermally grown oxide (TGO) forms on top of an initial 16.5-µm-thick coating. Cross-sectional nanobeam diffraction in conjunction with high resolution chemical as well as structural analysis during transmission electron microscopy after these exposures highlight that the Al-rich γ-TiAl coating is perfectly intermixed with the TNM substrate material. Already after 100 h oxidation at 850 °C, no interface between the Al-rich γ-TiAl coating and the TNM alloy can be identified chemically or structurally. The structural homogenization is governed by the transformation of all Al-rich phases (i.e., TiAl3 or Ti2Al5) – also present in the as-deposited state – towards γ-TiAl. After 1000 h at 850 °C, the predominant phase within the original coating region is γ-TiAl, next to the highly dense and well-adherent α-Al2O3-based scale.

Study on the microstructure and corrosion resistance of Zn-3Al-xMg alloy

Low-aluminium Zn-Al-Mg alloys (Al content is 1–3 %) were expected to be widely used in automotive panels due to their good coating properties and surface quality. However, the effect of Mg on the microstructure and corrosion resistance of Zn-Al-Mg alloys has not been studied thoroughly enough. In order to investigate the corrosion resistance law of Mg on Zn3Al alloys. The microstructure and corrosion resistance of Zn-3Al-xMg (x = 0.5, 1, 2, 3 wt%) alloys were investigated in the present work. The ternary eutectic (Zn/Al/MgZn2) in the microstructure increased, and the Al-rich phase disappeared with increasing Mg. The grains were also refined. The maximum ratio of ternary eutectic in the alloy was achieved by controlling the Mg content, contributing to the most favourable corrosion resistance. The electrochemical and corrosion behaviour analysis indicated that the Zn-3Al-2Mg alloy exhibited superior corrosion resistance due to the lower presence of Al-rich phases and a larger ternary eutectic area. However, the ternary eutectic in the alloy was completely transformed into Zn/Al/Mg2Zn11 when the Mg was 3 %, leading to decreased corrosion resistance. The corrosion resistance mechanisms of Zn-3Al-xMg were analyzed and discussed by studying the microstructure changes, electrochemical analysis, corrosion morphology, and products of the Zn-3Al-xMg alloy.