Corrosion Properties Of Magnesium Alloy Research Articles

A Critical Review on Improving the Fatigue Life and Corrosion Properties of Magnesium Alloys via the Technique of Adding Different Elements

Magnesium is the eighth-most abundant element in the world and its alloys have a widespread application in various industries such as electronic and transport (i.e., air, land, and sea) engineering, due to their significant mechanical properties, excellent machinability, high strength to weight ratios, and low cost. Although monolithic Mg metal is known as the lightest industrial metal (magnesium density is 30% less than the density of the aluminum, and this unique property increases the attractiveness of its usage in the transportation industry), one of the significant limitations of magnesium, which affects on its applications in various industries, is very high reactivity of this metal (magnesium with an electronegativity of 31.1 can give electrons to almost all metals and corrodes quickly). To overcome this problem, scholars are trying to produce magnesium (Mg) alloys that are more resistant to a variety of loads and environmental conditions. In this regard, Mg alloys include well-known materials such as aluminum (Al), Zinc (Zn), Manganese (Mn), Silicon (Si), and Copper (Cu), etc., and their amount directly affects the properties of final products. In the present review paper, the authors attempted to present the latest achievements, methods, and influential factors (finish-rolling, pore defects, pH value, microstructure, and manufacturing processes, etc.) on the fatigue life and corrosion resistance of most significant Mg alloys, including AM50, AM60, AZ31, AZ61, AZ80, AZ91, ZK60, and WE43, under various conditions. The summarized results and practical hints presented in this paper can be very useful to enhance the reliability and quality of Mg-made structures.

Improvement of corrosion and stress corrosion properties of magnesium alloys by coating aluminum with the electric arc spray method

AbstractIn this study, corrosion and stress corrosion behaviors of AZ31, AZ61, and AZ91 magnesium alloys coated with aluminum by the electric arc spray method were investigated in 3.5 wt.% NaCl solution. Structural properties of coated materials were investigated by scanning electron microscopy (SEM), energy dispersive X‐ray analysis, and X‐ray diffraction. Electrochemical properties were determined using the potentiodynamic polarization method in 3.5 wt.% NaCl solution. Potentiodynamic polarization curves showed that corrosion current density values did not change with coating in aluminum‐coated samples by the electric arc spray method. In contrast, corrosion potential value increased toward positive values. Slow strain rate test (SSRT) was used to determine the stress corrosion behavior and stress corrosion indexes (ISCC), ultimate tensile strength (UTS), and elongation of AZ31, AZ61, and AZ91 magnesium (Mg) alloys were determined. As a result of the SSRT, the aluminum coating process decreased significantly the stress corrosion indexes of AZ31, AZ61, and AZ91 Mg alloys. The fracture of surface images was also examined in the SEM, and both intergranular and transgranular stress corrosion cracking were observed in all three alloys.

Effect of Texture and Phase Composition on the Corrosion Properties of Magnesium Alloys

Effect of Texture and Phase Composition on the Corrosion Properties of Magnesium Alloys

Improving Wear and Corrosion Properties of Magnesium Alloy by Cold Sprayed Nano WC-17Co Coating

Improving Wear and Corrosion Properties of Magnesium Alloy by Cold Sprayed Nano WC-17Co Coating

Corrosion and chemical behavior of Mg97Zn1Y2-1wt.%SiC under different corrosion solutions

To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg97Zn1Y2-1wt.%SiC alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L−1 NaCl, Na2SO4 and NaNO3 were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy (OM), scanning electron microscopy (SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg97Zn1Y2-1wt.%SiC alloy is composed of α-Mg matrix, LPSO (Mg12ZnY) phase and SiC phase. The hydrogen evolution and electrochemical test results reflect that the Mg97Zn1Y2-1wt.%SiC in 0.2 mol·L−1 NaCl solution has the fastest corrosion rate, followed by Na2SO4 and NaNO3 solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.

One-step solve-thermal process for the construction of anticorrosion bionic superhydrophobic surfaces on magnesium alloy

Superhydrophobic surface with biomimetic micro/nanostructures was prepared in this study. The mammillaria-herrerae-like microspheres, carnation-like microclusters and carnation-petal-like nano-slices of biomimetic micro/nanostructures on magnesium alloy surface can create a stable superhydrophobic surface, which is similar to the “lotus leaf” structure. The as-prepared superhydrophobic surface had a contact angle of 158.5° and a sliding angle of 2.0°. Potentiodynamic polarization measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5wt% NaCl solution.

A rapid one-step process for the construction of corrosion-resistant bionic superhydrophobic surfaces

Abstract A simple, one-step method has been developed to construct a corrosion-resistant bionic superhydrophobic surfaces by solve-thermal process in an ethanol and water solution containing stearic acid. Superhydrophobic surface with biomimetic micronanostructures was prepared in this study. The Mammillaria herrerae-like microspheres, carnation-like microclusters and carnation-petal-like nanoslices of biomimetic micronanostructures on magnesium alloy surface can create a stable superhydrophobic surface, which is similar to the “lotus leaf” structure. The as-prepared superhydrophobic surface had a contact angle of 158.5° and a sliding angle of 2.0°. The as-prepared superhydrophobic surfaces were characterized by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and contact angle measurement. Potentiodynamic polarization measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt% NaCl solution.

One-Step Electrodeposition Process To Fabricate Corrosion-Resistant Superhydrophobic Surface on Magnesium Alloy

A simple, one-step method has been developed to construct a superhydrophobic surface by electrodepositing Mg-Mn-Ce magnesium plate in an ethanol solution containing cerium nitrate hexahydrate and myristic acid. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the surfaces. The shortest electrodeposition time to obtain a superhydrophobic surface was about 1 min, and the as-prepared superhydrophobic surfaces had a maximum contact angle of 159.8° and a sliding angle of less than 2°. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements demonstrated that the superhydrophobic surface greatly improved the corrosion properties of magnesium alloy in 3.5 wt % aqueous solutions of NaCl, Na2SO4, NaClO3, and NaNO3. Besides, the chemical stability and mechanical durability of the as-prepared superhydrophobic surface were also examined. The presented method is rapid, low-cost, and environmentally friendly and thus should be of significant value for the industrial fabrication of anticorrosive superhydrophobic surfaces and should have a promising future in expanding the applications of magnesium alloys.

Tungstate ion-assisted hydrothermal conversion of magnesium hydroxide coatings on AZ31 magnesium alloy

Surface modifications are often employed to improve the corrosion properties of magnesium alloys. In this study, the eco-friendly magnesium hydroxide (Mg(OH)2) conversion coatings were successfully applied on AZ31 substrates through hydrothermal treatment with the assistance of tungstate ions. Phase composition, surface and interface morphologies, surface composition, and adhesion property were characterised using X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and scanning scratch tester respectively. The coating obtained was fairly dense and uniform. Coating thickness increased with the increase of hydrothermal treatment time, but longer times ( > 6 h) has a detrimental effect on the coating quality. The combined effect of adsorption and complexing of tungstate ions can effectively change the growth of Mg(OH)2 crystal from anisotropic to isotropic. This effect was crucial to produce the dense and uniform conversion coating. Scratch test indicated that the conversion coating adhered to the substrate strongly. Electrochemical testing revealed that the conversion coating caused AZ31 to be of higher corrosion potential with a much lower corrosion current density. This current study provides a promising surface treatment method for magnesium alloys towards their further applications.

Corrosion Behaviors in Simulated Body Fluid for TiO<sub>2</sub> Films Deposited on AZ31 Magnesium Alloys by Magnetron Sputtering

TiO2 films were deposited on AZ31 magnesium alloy substrates by r.f. magnetron sputtering. The corrosion behaviors in simulated body fluid (SBF) of the film samples were investigated and compared to the bare AZ31 magnesium alloy. After 3 days’ corrosion in SBF, only part of the TiO2 layer suffered from corrosion and the substrate was prevented from corrosion. In contrast, the bare magnesium alloy suffered from severe corrosion. After 10 days’ corrosion, the TiO2 layer was penetrated and the substrates still did not suffer from corrosion. After 15 days’ corrosion, besides TiO2 layer, the substrate suffered from corrosion to some degree. The depth of the corrosion layer is about 6 m, which is far lower than that of bare magnesium alloy, 40 m. The results show that TiO2 films effectively improve the corrosion properties of magnesium alloys.

Corrosion Behavior of As-Cast Binary Mg-Dy Alloys

The addition of rare earth elements (REE) is an effective way to improve the corrosion properties of magnesium alloys. Dysprosium has a very high solubility in Mg (25.3 wt.% at 561 °C) and could therefore be a promising alloying element for Mg based implants. In this study, four binary Mg-xDy (x=5, 10, 15 and 20 in wt.%) alloys were prepared by permanent mould direct chill casting. Microstructure and Dy distribution were investigated using optical microscope and EDX analysis. Corrosion rate was measured with hydrogen evolution method and corrosion morphology was observed after immersion for different time in 0.9 wt% NaCl solution with optical and SEM. The results show that with the increase of Dy, the amount of Dy in Mg matrix and area of Dy segregation are both increased. At the same time, the amount of second phase is also increased. Filiform corrosion is reduced while pitting corrosion is increased with the increment of Dy. As a result, lowest corrosion rate is obtained at Mg-10Dy alloy.

Investigation about Corrosion Properties of AZ31 Magnesium Alloy Coupled with Nitrided 40Cr Steel

Corrosion properties of magnesium alloys coupled with foreign metals impose much influence on the life of the parts. In this paper, the corrosion properties of AZ31 magnesium alloy coupled with nitrided 40Cr steel were investigated through immersion test in saline solution and weight loss test combining with optical microscope (OM) and scanning electronic microscope (SEM) analysis. The results indicate that the anticorrosion properties of the AZ31 magnesium alloy coupled with nitrided 40Cr steel are higher than those of the AZ31 magnesium alloy coupled with unnitrided 40Cr steel. The mechanism is attributed to the resultant nitrided layer which reduces the conductive properties.

Influence of grain size on mechanical and corrosion properties of magnesium alloy for medical implants

AbstractThe microstructure, mechanical property and corrosion behavior of magnesium alloy WE43 (MgYNdZr alloy) in the environment simulating biological fluid were investigated. Samples of ultra‐fine‐grained magnesium alloy with high mechanical properties were obtained by methods of severe plastic deformation. Programmed plastic deformation was realized by two methods: extrusion alternating with upsetting at gradually lowering the temperature and equal‐channel angular pressing.

Improvement of mechanical and corrosion properties of magnesium alloy by lead addition

Mechanical properties and corrosion behaviour of AZ91 magnesium alloy containing 0.2–1.0 wt.% Pb were investigated. An enhancement of ultimate tensile strength by 42%, yield strength by 58% and elongation by 20% can be achieved by Pb addition. Corrosion resistance of the AZ91 alloy also increased progressively with increasing Pb content. The mechanism of property enhancement is ascribed to the suppression of intermetallic phases (β-Mg 17Al 12 and α-Mg + β eutectic) by Pb addition.

Effect of CeCl<sub>3</sub>-Containing Flux on Microstructure and Mechanical Properties of Mg Alloy Containing Rare Earth

The effects of CeCl3-containing fluxes on RE element loss, the high temperature mechanical properties, microstructure and corrosion properties of magnesium alloy containing RE have been studied. The results showed that a certain amount of CeCl3 in purification fluxes restrained the reaction between the Ce element and fluxes to decrease the loss of Ce in alloys. With the flux containing 9% CeCl3, the loss rate of alloy element Ce can be reduced from 26.9% to 3.4%, and the σb and δ of the alloys at 150°C counld be improved from 160.9MPa and 6.2% to 176.5MPa and 7.9% compared with that of conventional MgCl2-containing flux , respectively. Besides, the coarse β phase and rod-like RE phase were refined effectively by CeCl3-containing fluxes.