Outstanding Corrosion Resistance Research Articles

Mechanical, wear and corrosion behaviours of laser additive manufactured iron-based heterogeneous composite coatings for tillage tools

Steel is commonly used in engineering components, and it has a high tendency to wear and corrosion attacks when exposed to unfavourable working conditions. The use of chromium-vanadium-iron-rich carbide reinforced iron-based hard facings has become more important in improving the corrosion and wear resistance of such steel subjected to abrasive and impact conditions. In this study, the chromium-vanadium-iron carbide reinforced coatings were developed using in-situ by depositing FeCrV15+Cr powder through laser cladding on carbon steel. The influence of the reinforcement on the microstructure of the coating in relation to its laser processing condition and extra chromium addition was investigated. Furthermore, the effect of the coating's reinforcement on the hardness, microstructures, anti-corrosion, and anti-wear properties of the carbon steel used in tillage and mining operations was investigated. The result is a defect free deposits with a solid metallurgical attachment to the substrate and improved microhardness. FeCrV15 deposits had a wear-resistant (with a wear rate of 2.42 × 10−6 mm3/N/m) and anti-corrosion capability (with a corrosion rate of 0.001869 mm/yr) that were several folds higher than the steel substrate (with wear rate of 1.72 × 10−3 mm3/N/m and corrosion rate of 0.1168 mm/yr). The general grain refinement of the FeCrV15 deposits was richly enhanced in the iron base matrix. This resulted in outstanding wear and corrosion resistance attributed to the better production of VC–Cr3C2–Cr7C3 particles and better grain refinement of the microstructural formation.

Interfacial swelling engineered superhydrophobic and electrically conductive coatings for multifunctional piezoresistive sensors

Conductive foam composites (CFCs) based pressure sensors show promising applications in flexible electronics, but it is still difficult to develop cost-effective methods for preparation of multifunctional CFC pressure sensors with a large working strain and environment tolerance. Herein, a facile “carbon nanotubes (CNTs) decoration and simultaneous hydrophobization” method is proposed to fabricate electrically conductive and superhydrophobic foam composites. CNTs/stearic acid (SA) are anchored onto the skeleton of the partially swelled styrene-butadiene rubber (SBR) foam via one step ultrasound-assisted interface sintering. The obtained superhydrophobic SA/CNTs decorated foam composites (SCFCs) with strong interfacial adhesion exhibit outstanding corrosion resistance and durability. SCSF piezoresistive sensors show a wide compressive strain sensing range (10–95 %) and a great durability over 11,000 cycles and can work normally in underwater or even corrosive conditions. In addition, SCFCs possess excellent photothermal conversion performance and their resistance exhibits negative temperature coefficiency, making them promising as temperature sensors.

Super-hard and well-tough (TiZrVCrCoNi)Nx high entropy nitride coatings with biphasic nanocomposite structure

High entropy nitride (HEN) coating is a new choice to replace traditional nitride as a protective coating. Through rational composition design, (TiZrVCrCoNi)Nx HEN coatings under different N2 gas flow rates (RN) were fabricated by multi-target magnetron co-sputtering deposition. The increasing RN enhanced N content in the HEN coatings, which influences the structural, mechanical, and corrosion characteristics of the coatings. The increase of N content caused the phase structure to transform from an amorphous phase to a face-centered-cubic (FCC) phase in the coatings. At a high N content of 47.7 at.% (RN = 15 sccm), the coating with a biphasic nanocomposite structure exhibits a high-quality combination of super-hardness, good toughness, anti-friction property, and excellent corrosion resistance. While the hardness can reach the super-hard level (40.9 ± 0.75 GPa), the toughness is not decreased much (3.35 ± 0.08 MPa m1/2). Besides, the corrosion current density of it (1.86 × 10−8 A/cm2) is nearly two orders of magnitude lower than 304 stainless steel (1.24 × 10−6 A/cm2). Therefore, (TiZrVCrCoNi)Nx HEN coatings present outstanding mechanical properties and corrosion resistance, which have potential applications in various fields.

Synergy of Mo doping and heterostructures in FeCo2S4@Mo-NiCo LDH/NF as durable and corrosion-resistance bifunctional electrocatalyst towards seawater electrolysis at industrial current density

Electrolysis of seawater to produce hydrogen is a replenished way to utilize sustainable hydrogen energy. However, it remains a challenge to develop electrocatalysts with high chloride corrosion resistance and meet the industrial-required low overpotential at large current density. Here, a heterostructure FeCo2S4@Mo-NiCo LDH/NF (FCS@M-NC LDH/NF) catalyst consisting of Mo-doped NiCo LDH nanosheets on FeCo2S4 nanorods grown on nickel foam is demonstrated as a large-current–density electrocatalyst for seawater electrolysis. The hierarchical structure endows FCS@M-NC LDH/NF with abundant active sites and hydrophilic and aerophobic surfaces, which promotes the adsorption of OH− and accelerates gas-release capabilities during water electrolysis. Moreover, the incorporation of high-valence Mo species and the presence of heterostructures contribute to the outstanding corrosion resistance, selectivity, and activity of FCS@M-NC LDH/NF, which only requires 314 mV (HER) and 307 mV (OER) overpotential to achieve a large current density of 1000 mA cm−2 in alkaline electrolysis of seawater. Impressively, it maintains stable operation for 140 h at a current density of 500 mA cm−2 without the production of hypochlorite. Furthermore, density functional theory calculations demonstrate that Mo doping and formation of heterostructures decrease the adsorption energy barrier for intermediate on FCS@M-NC LDH/NF, which promotes electrocatalytic activity. The robust electronic interaction between FCS and M-NC LDH/NF promotes the redistribution of charges on the interface, boosting electrical conductivity and charge transfer in the FCS@M-NC LDH/NF. This study offers a mild way to create a bifunctional electrocatalyst with exceptional corrosion resistance and stability in industrial high-alkaline natural seawater electrolysis.

Robust and Corrosion-Resistant Overall Water Splitting Electrode Enabled by Additive Manufacturing.

Electrolysis of water has emerged as a prominent area of research in recent years. As a promising catalyst support, copper foam is widely investigated for electrolytic water, yet the insufficient mechanical strength and corrosion resistance render it less suitable for harsh working conditions. To exploit high-performance catalyst supports, various metal supports are comprehensively evaluated, and Ti6 Al4 V (Ti64) support exhibited outstanding compression and corrosion resistance. With this in mind, a 3D porous Ti64 catalyst support is fabricated using the selective laser sintering (SLM) 3D printing technology, and a conductive layer of nickel (Ni) is coated to increase the electrical conductivity and facilitate the deposition of catalysts. Subsequently, Co0.8 Ni0.2 (CO3 )0.5 (OH)·0.11H2 O (CoNiCH) nanoneedles are deposited. The resulting porous Ti64/Ni/CoNiCH electrode displayed an impressive performance in the oxygen evolution reaction (OER) and reached 30mAcm-2 at an overpotential of only 200mV. Remarkably, even after being compressed at 15.04MPa, no obvious structural deformation is observed, and the attenuation of its catalytic efficiency is negligible. Based on the computational analysis, the CoNiCH catalyst demonstrated superior catalytic activity at the Ni site in comparison to the Co site. Furthermore, the electrode reached 30mAcm-2 at 1.75V in full water splitting conditions and showed no significant performance degradation even after 60h of continuous operation. This study presents an innovative approach to robust and corrosion-resistant catalyst design.

Mechanical hydroxyapatite coatings on PEO-treated Ti–6Al–4V alloy for enhancing implant's surface bioactivity

In this study, to reactivate the oxide film and to secure biocompatibility, plasma electrolytic oxidation (PEO) treatment and hydroxyapatite (HA) deposition via mechanical coating (MC) processes were investigated. This experimental approach involved subjecting the Ti–6Al–4V alloy specimens to PEO treatment, followed by MC with HA powder for different hours as HA has the potential to increase bioactivity and surface characteristics due to its chemical composition and structural properties similar to natural bone. Therefore, the study aimed to examine the effects of MC with HA powder for 0, 1, 3, 5, 7, and 9 h on PEO-coated Ti–6Al–4V alloy discs for analyzing the surface characterization, phase analysis, surface roughness, wettability, adhesion strength, hardness, corrosion behavior, and cell proliferation properties for dental implant use. The findings demonstrate that prolonged HA milling enhances the substrate's mechanical strength, corrosion resistance, and adhesion properties. The presence of prominent anatase and HA peaks, particularly in the 5 MC-PEO, 7MC-PEO, and 9 MC-PEO samples, validates the synergistic impact of the PEO oxide layer and HA milling, resulting in outstanding corrosion resistance and biocompatibility. Cell culture analysis reveals a positive correlation between increased milling time and enhanced cell proliferation, particularly towards small-sized HA particles.

Development of a sprayable PVA-fiber-enhanced cement mortar with high acid-corrosion resistance for pipeline rehabilitate

The spraying method offers the advantages of environmental protection, convenient construction, and cost-effectiveness, making it widely used in pipeline structure repair. Given the complex service environment of pipelines, there is an urgent demand for high-strength and durable spraying materials. To achieve this goal, a PVA fiber reinforced cement mortar material (PFCM) with high early strength, excellent impermeability and stable acid corrosion resistance was developed through orthogonal test design. The optimal material was obtained through factors such as setting time, fluidity, compressive strength and flexural strength. The effects of the contents of fly ash, redispersible polymer powder and PVA fiber on the working and mechanical properties of the material were investigated, and further research was conducted on its tensile strength, impermeability, acid corrosion resistance. In addition, Thermogravimetric-differential Thermal Analysis (TG-DTA) was utilized to analyze the thermal stability of PFCM. X-ray diffraction (XRD) was utilized to analyze the composition of PFCM. Mercury intrusion porosimetry (MIP) was utilized to analyze the pore structure of PFCM, and the feasibility of the PFCM was verified. The results indicate that the contents of fly ash, redispersible polymer powder and PVA fiber have significant effects on the working and mechanical properties. The optimum initial setting time is 60–80 min, and the optimum fluidity is between 170 and 180 mm. The compressive strength and flexural strength of the mortar prepared with the optimum parameters are 102.5 MPa and 20 MPa, respectively. The material has an excellent spraying effect with no sagging, and exhibits high early strength, outstanding corrosion resistance, low porosity, and exceptional impermeability. This study lays the foundation for achieving high-quality spray repairs of underground drainage pipelines.

Discoloration on Laser Welds of AISI 321 Tubes

Abstract In this contribution, a fabrication problem is discussed, related to Laser Beam Welding (LBW). Strictly speaking, the case study presented herein does not constitute a failure as such, since the subject components never made it to component service. In the narrow sense of the word, a component failure happens if and when a part does no longer serve its proper function. This is definitely not the case in the study put forward in this paper. However, one could argue that a product that cannot be marketed for lack of certain properties, or because of certain shortcomings, is rendered worthless for the manufacturer and this, in turn, could be considered a failure. In this case study, the issue of discoloration on the surfaces of welded austenitic stainless steel is discussed. This is a well-known and well-researched fabrication problem. Dependent upon service conditions of affected parts, discoloration might be detrimental to the normally outstanding corrosion resistance of this class of high-alloy steels.

Hybrid aliphatic and aromatic diisocyanates forming mixed urea segments for high-performance polyurea

Polyurea is gaining more traction in the realm of protective coatings on metal surfaces from corrosion. The properties of polyurea can be controlled by the judicious selection of its reactants. Herein, a series of polyurea based on hybrid aliphatic/aromatic diisocyanates are synthesized from isophorone diisocyanate (IP) and polycarbodiimide-modified diphenylmethane diisocyanate (ISO). The formulation composed of 37.5:62.5 (IP: ISO) weight ratio yields the highest tensile strength at 47.80 MPa, elongation at 500 %, and hardness of 95 HA. The findings are validated through field emission scanning and atomic force microscopic analysis, which reveals phase mixing surface and ductile fracture containing wide-ranging stretching lines due to enhanced resistance to deformation. Furthermore, synthesized polyureas present a unique stress relaxation pattern with gradual increase in stress under constant deformation, due to hydrogen bond reformation and dislocation creations during chain alignment. IP37.5-ISO62.5 demonstrates outstanding corrosion resistance after a 28-day exposure in salt spray test.

Synthesis and characterization of ternary nanocomposite based on Ag-Fe3O4/rGO for electrochemical application

In-situ synthesis of a ternary nanocomposite based on Ag-Fe3O4/rGO by utilizing Azadirachta indica leaf extract as a reducing agent has been carried out. The morphological, EDX, and structural analyses confirm the reduction of GO into rGO by forming crystalline Fe3O4 and Ag nanoparticles in the rGO matrix, with a crystalline size of 25.77 nm. Further, the FTIR, UV-Vis, and BET analyses confirmed the effective interaction between Fe3O4 and Ag nanoparticles in the rGO matrix, tunable bandgap, and a higher specific surface area. Various electrochemical techniques such as cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy have been performed in a 2 M KOH electrolyte to investigate its electrochemical performance. The synthesized ternary nanocomposite exhibits a specific capacitance of 493 Fg−1 at a current density of 1 Ag−1, with notable capacitive retention of 91.5% even after 10,000 cycles. This nontoxic technique provides a substitute pathway for the formation of graphene-based ternary nanocomposites with exceptional structural, morphological, optical, surface, and electrochemical properties. The ternary nanocomposite synthesized through this procedure displays an outstanding specific capacitance, cyclic stability, and corrosion resistance and hence the possibility of using nanocomposite as a promising electrode material can be explored for energy storage devices.

Simple preparation of UV-absorbing and magnetic superhydrophobic membranes by one-step electrospinning for effective oil–water separation

Developing multifunctional separation membranes, especially composite separation membranes that are corrosion-resistant, fouling-resistant, and easy to collect, has become a new challenge to treating oily wastewater in complex environments. Therefore, superhydrophobic magnetic membranes composed of polystyrene/poly(acrylonitrile)-poly(vinylidene fluoride)/poly(dimethylsiloxane)-iron oxide/titanium dioxide nanoparticles (PS/PAN-PVDF/PDMS@Fe3O4/TiO2), which possess exceptional corrosion resistance and UV absorption properties, were fabricated through the process of electrospinning. Controlling the doping ratio of Fe3O4/TiO2, composite membranes with excellent superhydrophobicity (156.9°), mechanical properties (3.67 MPa and 75.93 %), and thermal stability (330 °C) were obtained. The membrane demonstrates outstanding corrosion resistance (WCA > 150°) even after being immersed in various corrosive solutions for 120 h. Under visible-ultraviolet irradiation, the membrane has excellent UV absorption and exhibits a significant red-shift phenomenon, providing a certain degree of resistance to fouling. In the presence of a magnetic field, the membrane has a maximum saturation magnetization of 9.98 emu/g, which the magnetic field drive can attract. The oil adsorption capacity of the membrane was 29–112 g/g, which also maintained 88 % of the initial value after ten cycles. In addition, a comprehensive evaluation was conducted to assess the fabricated composite membrane's separation flux, efficiency, and cycle life when exposed to acidic and alkaline corrosive solutions. The results indicated that even after 40 cycles, the membrane's oil–water separation flux and separation efficiency remained at 6971 L.h−1.m−2 and 97 %, respectively, representing a 24.2 % increase compared to the unmodified membrane. Therefore, the membrane exhibits promising potential for treating oily wastewater in harsh environments.

Preparation of fully epoxy resin microcapsules and their application in self-healing epoxy anti-corrosion coatings

Herein, an innovative self-healing epoxy coating with outstanding corrosion resistance has been developed. The self-healing capability of the coating is achieved by embedding microcapsules, comprising of solidified epoxy resin as the outer layer and liquid epoxy resin as the inner content. The chemical composition of the microcapsule wall is identical to that of the coating substrate, it is equivalent to injecting the liquid repair agent directly into the coating. Remarkably, due to the absence of any additional components in the coating system, the microcapsules seamlessly integrate with the resin matrix of the coating, showcasing exceptional compatibility.

Comparative study on the corrosion resistance of Al, AlTiSi and AlTiSiN coated Mg-Gd-Y magnesium alloy

Aluminum rich coatings have been proven to be promising protective coatings in magnesium alloy products due to their high potential and ability to form passive films. This work reports the corrosion resistance of Al, AlTiSi and AlTiSiN coatings synthesized by magnetron sputtering on AZ80M magnesium alloy. The results show that the AlTiSiN coated magnesium alloy exhibits the outstanding corrosion resistance with obviously high polarization resistance (Rp) and corrosion potential (Ecorr), and significantly low corrosion current density (Icorr), due to its greatly compact and directionless structure. The salt spray test confirms that the AlTiSiN coated magnesium alloy has more durable resistance to chloride ion immersion compared to Al and AlTiSi coated magnesium alloy.

Stiffness enhancement of polymer nanocomposites via graphene nanoplatelet orientation

AbstractIn the development of National Aeronautics and Space Administration (NASA)'s Unmanned Aerial Vehicles (UAVs), lightweight and durable materials play a crucial role for extended high‐altitude flights. Nanoparticle‐reinforced polymer composites meet these requirements, exhibiting resistance to environmental degradation. Despite their potential, the outstanding specific strength, corrosion resistance, and dimensional stability at elevated temperatures of graphene–epoxy nanocomposites have not been fully realized due to inadequate dispersion and spatial orientation within epoxy matrices. Our recent research has introduced a mathematical framework aimed at optimizing alignment parameters for graphene nanoplatelets (GNPs) and Fe3O4‐attached GNP under a weak DC magnetic field. Subsequently, nanocomposites reinforced with GNP and aligned Fe3O4–GNP nanoparticles were fabricated using optimized parameters, and their alignment was characterized using various techniques. The current study examines the influence and comparative impact of alignment and weight percentage (wt%) loading of both nanoparticles on various mechanical properties, including tensile and compressive strength, along with failure mechanisms. It was observed that both GNP and aligned Fe3O4–GNP enhance the mechanical properties of nanocomposites, particularly notable improvements from aligned Fe3O4–GNP. The Young's modulus of GNP nanocomposites increased by 17%, while aligned Fe3O4–GNP contributed significantly to a 31% enhancement in the Young modulus.Highlights Epoxy nanocomposites featuring well‐dispersed GNP and Fe3O4–GNP nanoparticles. Proper alignment of Fe3O4–GNP within the epoxy nanocomposite was achieved. Mechanical properties improved with GNP and aligned Fe3O4–GNP incorporation. The aligned Fe3O4–GNP exhibits advanced potential for engineering applications.

Designing multifunctional basalt-CeO2@C3N4/epoxy novolac composite coating with outstanding corrosion resistance and CO2 gas barrier properties

The greenhouse effect caused by CO2 emissions is becoming more and more serious, and the carbon capture, utilization and storage (CCUS) is a feasible strategy to reduce emissions. However, the corrosion problem brought by CCUS is unprecedentedly serious. In this paper, we present a composite epoxy novolac (EN) system for resisting corrosion of metals in CCUS environments. In this system, nanorod CeO2 and nanosheet C3N4 are simultaneously grown on the surface of the micron sheet basalt (Bt), which are used as effective additives to improve the corrosion resistance and CO2 gas barrier properties of EN. Only with 3 % of nanoparticles addition, a significant reduction of the gas diffusion of composite film to dry CO2 has been observed, up to 5.88 × 10−12 m2/s. This is associated with the synergistic enhancement of the physical shielding effect by the nano and micron sheets. Additionally, we found that adsorption of oxygen vacancy of CeO2 material with CO2 enhances the stability of corrosion resistance. Therefore, the |Z|0.01 Hz of the Bt-CeO2@C3N4/EN coating is above 106 Ω cm2 higher than that of the EN coating after 25 days of immersion in a 3.0 MPa CO2 aqueous solution at 70 °C. Overall, the anti-corrosion coating system combines long-lasting water resistance and low CO2 gas transmission in harsh corrosive environments, and thus has a high potential for CCUS applications.

Correlation of microstructure, mechanical properties and corrosion behavior in a Ni34Co28Cr28Al10 multi-principal element alloy with outstanding corrosion resistance

Microstructure, mechanical properties and corrosion behavior of a Ni34Co28Cr28Al10 multi-principal element alloy (MPEA) were investigated at different states. The as-cast and aged samples exhibited a primary face-cubic centered (FCC) phase and some B2 phase, wherein the FCC phase contained L12 precipitates and the B2 phase contained body-cubic centered (BCC) precipitates. The homogenized sample displayed a single FCC phase. The as-cast sample exhibited the best combination of mechanical properties and corrosion resistance, resulting from multiple strengthening mechanisms, and Al-rich L12 and B2 precipitates which could suppress the transfer of Al atoms to surface leading to increased Cr content in passive film.

Decision Science-Driven Assessment of Ti Alloys for Aircraft Landing Gear Beams

Titanium alloys, with their low density, exceptional mechanical properties, and outstanding corrosion resistance, play a vital role in various aerospace applications. Our decision science-driven assessment focused on metastable β, near-β, α + β, and near-α Ti alloys for landing gear applications, integrating multiple-attribute decision-making (MADM) methods, principal component analysis (PCA), and hierarchical clustering (HC) is based on current literature. The ranks of the alloys evaluated by diverse MADM methods were consistent. The methodology identifies five top-ranked Ti alloys assists and verifies the guidelines for alloy design. The top-ranked alloy, Ti1300-BM-nano-α (alloy chemistry: Ti-5Al-4V-4Mo-3Zr-4Cr, solution treatment: 800 °C for 1 h followed by air cooling—solution treated below β transus, and aging: 500 °C for 4 h followed by air cooling), stands out with a percentage elongation (%EL) ~3.3 times greater than the benchmark or goal (density, d = ~4.6 g/cm3; yield strength YS = ~1250 MPa; %El = ~5), while maintaining similar density and yield strength. The analyses underline that metastable β Ti alloys comprising globular primary α + trans β matrix coupled with α precipitates in trans β are the base optimal microstructure to fine-tune using thermomechanical processing for aircraft landing gear applications.

Comparison of the Effects of Vegetable Oils such as Castor and Canola Oil and Polyol Esters on the Metalworking Performance of Ti-6Al-4VAlloy by Tapping Torque Method

Ti-6Al-4V material is an alloy of particular interest for engineering applications in a wide range of industries, especially aerospace and medicine, due to its outstanding corrosion resistance, favorable strength-to-weight ratio and biocompatibility properties. Due to the low thermal conductivity and high chemical reactivity of this alloy, its machinability is quite limited and is therefore referred to as the "difficult-to-cut" alloy. When the problems encountered in the processing of Ti-6Al-4V alloy are evaluated, the preparation of the appropriate cutting environment, ensuring optimum cutting parameters and the use of appropriate coolant are the priorities in overcoming these problems. Vegetable oil and polyol esters are biodegradable base fluids that can be used as a sustainable alternative to petroleum-derived oils in many lubricant applications. In this study, the effects of castor and canola oils and trimethylolpropane trioleate (TMPTO) and trimethylolpropane trioleate complex (TMPCX), neopentyl glycol (NPG) and pentaerythritol tetra-oleate (PE-TO) type polyol esters on the machining performance of Ti-6Al-4V alloy were investigated using the Tapping Torque test method. In the tests performed on Ti-6AL-4V, it was determined that the tapping performances of TMP-TO, TMP-CX, PE-TO and castor oil were close to each other and gave the best results. It has also been determined that the tapping performance of canola oil is lower than these oils. NPG-DO gave a striking result for Ti-6AL-4V and the tapping performance was found to be very low.

Anti-corrosive and self-healing properties of epoxy coatings loaded with montmorillonite modified with zinc-based ionic liquid

In this work, the outstanding corrosion resistance of coated steel and self-healing ability of epoxy coatings loaded with 1 % of sodium montmorillonite (MMT-Na+) clay modified with bis-(1-butyl-3-methylimidazolium) zinc tetrachloride (bmim2[ZnCl4]) was successfully demonstrated. The corrosion protection properties and self-healing ability of artificially scratched ER coatings containing 1 % of MMT-bmim2[ZnCl4] were compared with those loaded with MMT-Na+, MMT-ZnCl2 and the MMT modified with the ionic liquid 1-butyl-3-methylimidazolium chloride (bmimCl), using electrochemical impedance spectroscopy (EIS) under saline medium. The presence of 1 % clay modified with ZnCl2 and bmim2[ZnCl4] promoted outstanding anti-corrosion protection to the scratched ER coatings. The last one exhibited the best anti-corrosive response, whose |Z|f=0.01Hz value corresponded to 2.9 × 106 Ω·cm2 after 24 h immersion and increased by around two orders of magnitude after 360 h immersion in saline solution. Furthermore, the charge transfer resistance (Rct) increased after 360 h immersion followed by significant decrease in double-layer capacitance values (Cdl) at the electrolyte/metal interface. The self-healing ability was also confirmed by SEM/EDX (due to the presence of Zn in the scratched region) and by visual observation of the scratched region after immersion in the saline solution for 360 h.

Effects of rare-earth element Y content on the microstructure and properties of quinary Al–Ni–Zr–Co–Y high entropy metallic glasses

A series of quinary (Al1/4Ni1/4Zr1/4Co1/4)100-xYx (x = 16–28 at.%) high entropy metallic glass ribbons were successfully fabricated through the high-speed single roller melt-spinning method. The effects of rare-earth element yttrium content on the microstructure and performances of alloy ribbons were systematically investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), heat treatment, transmission electronic microscopy (TEM), atomic force microscopy (AFM) and electrochemical experiments. The microhardness of metallic ribbons was measured by Vickers hardness tester. Results show that the microstructure of the as-quenched alloy ribbons maintain the glassy state and the average microhardness value of each specimen can reach 488 HV0.1 or above. The surface morphologies of the as-spun ribbon samples exhibit the smooth surface with small roughness value of Ra = 0.115–0.150 nm. In the meantime, with the increase of Y content, the glass transition temperature can be detected in the DSC traces when Y content is over 22 at.%, and the crystallization onset temperature shifts to the lower temperature region, suggesting that the thermal stability of amorphous state in Al–Ni–Zr–Co–Y alloy ribbons has been weakened. The (Al1/4Ni1/4Zr1/4Co1/4)84Y16 alloy ribbons own the highest crystallization onset temperature (∼742 K). Adding appropriate yttrium element can enlarge the super-cooled liquid region and improve the glass-forming ability. In 3.5 wt% NaCl solution, the prepared alloy ribbons can maintain smaller corrosion current densities (∼10−8 A cm−2) than traditional Al-based amorphous alloys, 6061 Al alloy and other common structural steels. The X-ray photoelectron spectrometer results indicate that the passive film of equiatomic alloy ribbons is rich in oxides of Al, Zr, Co, and Y elements, which has excellent resistance to chloride ion attack. On the basis of all experimental results, (Al1/4Ni1/4Zr1/4Co1/4)84Y16 alloy ribbons can optimally combine outstanding corrosion resistance, superior thermal stability, and acceptable microhardness. The above research results lay a solid foundation for the composition development of high-performance high entropy metallic glasses.