Corrosion Behavior Of Magnesium Alloy Research Articles

Effect of Aluminum Content on the Crevice Corrosion Behavior of Magnesium Alloys

Effect of Aluminum Content on the Crevice Corrosion Behavior of Magnesium Alloys

Effect of laser cavitation peening on surface integrity and electrochemical corrosion behavior of magnesium alloy

A novel method of laser cavitation peening (LCP) was employed to process the AZ31B magnesium (Mg) alloy. The processes of bubble evolution and LCP impact were investigated. The influences of LCP on the surface integrity (surface morphology and roughness, microhardness, residual stress, phase) and electrochemical corrosion behavior of AZ31B Mg alloy under various processing parameters (laser energy and defocusing amount) were systemically investigated. The results show that the laser breakdown extent, bubble radius, pulsation period, and bubble energy increase with the increase of laser energy. The maximum radius of the cavitation bubble decreases significantly as the defocusing amount increases from 0 mm to 2 mm. LCP enhances the microhardness and introduces the compressive residual stress into the surface layer of the AZ31B, but it also increases the surface roughness. The surface morphology of LCP processed AZ31B has significant differences under various processing parameters, and the microhardness and residual stress increase as increasing the laser energy. LCP improves the anti-corrosion of AZ31B effectively except for the condition of 200 mJ laser energy. The best defocusing amount for enhancing the surface integrity and electrochemical performance of AZ31B by LCP processing is 1 mm, and the higher laser energy has the better corrosion resistance.

The effect of selected corrosion inhibitors on localized corrosion of magnesium alloy: The expanded understanding of "inhibition efficiency"

Research about magnesium corrosion inhibitors focuses on their influence on corrosion rate, but little attention is paid to whether the service reliability of alloys is improved by the inhibitors. In this work, the effects of selected corrosion inhibitors on the corrosion rate and localized corrosion behavior of magnesium alloy were compared. It is found that some corrosion inhibitors fail to inhibit the localized corrosion of magnesium, resulting in the inability to effectively maintain the mechanical bearing capacity of the corroded magnesium alloy. This study is of great significance for establishing reasonable screening and evaluation criteria for magnesium alloy corrosion inhibitors.

Machine Learning in Enhancing Corrosion Resistance of Magnesium Alloys: A Comprehensive Review

While magnesium alloys have garnered attention for their lightweight properties across diverse applications, their susceptibility to corrosion presents a formidable challenge. Recent years have witnessed the emergence of machine learning (ML) as a formidable tool for predicting and augmenting material properties, notably corrosion resistance. This comprehensive review investigates the latest advancements and hurdles in utilizing ML techniques to investigate the corrosion behavior of magnesium alloys. This article delves into a spectrum of ML algorithms, encompassing artificial neural networks, support vector machines, and random forests, elucidating their roles in predicting corrosion rates, morphologies, and other corrosion-related characteristics in magnesium alloys. Furthermore, it underscores the pivotal challenges and opportunities within this field, such as data quality, model interpretability, and model transferability. Finally, it examines the potential of ML methods in the conception and enhancement of magnesium alloys endowed with superior corrosion resistance. This review aspires to offer valuable insights into harnessing ML’s potential for optimizing magnesium alloy designs with heightened corrosion resistance, a facet of paramount importance across diverse industries, including the automotive, aerospace, and biomedical sectors. By addressing the challenges inherent in using ML to forecast corrosion rates, including data limitations and the intricacies of corrosion mechanisms, ML stands poised to emerge as a potent instrument for advancing the development of corrosion-resistant materials.

Prediction of electrochemical corrosion behavior of magnesium alloy using machine learning methods

The corrosion of magnesium (Mg) alloys is a major challenge in many industrial applications because of their extreme reactivity, this greatly limits their applicability. The traditional methods in the prediction of corrosion rate depend on experimental or empirical models that can be time-consuming and expensive. Besides how to integrate experiments with faster machine-learning approaches is still a challenge of research. In recent years machine learning (ML) algorithms have proved and promised better magnesium corrosion predictability. In this study, different training algorithms such as linear regression (LR), decision tree (DT), extra tree (ET), random forest (RF), K-nearest neighbor (KNN), extreme gradient boosting (XGBoost), and Artificial Neural Network (ANN) were used to develop and predict corrosion rate of magnesium alloys based on magnesium chemical alloy composition as independent input variables. The data used for model preparation and validation were obtained from literature and experimental studies respectively. The feature selection methods were used to identify the most important and influential input parameters for magnesium alloy thus Shapley Additive Explanations (SHAP) interpretation was employed in this manuscript to facilitate feature visualization of the model. The results of the study show that the random forest (RF) algorithm has the greatest prediction impact than other machine learning algorithms. The magnesium alloy corrosion prediction model provides a better ability for the prediction of magnesium corrosion alloys. The study demonstrates the potential of ML models in the prediction of the corrosion behavior of Mg alloys and these models can be used to optimize an alloy composition for designing improved corrosion resistance of new Mg alloys.

Effect of Fluoride Coatings on the Corrosion Behavior of Mg-Zn-Ca-Mn Alloys for Medical Application.

The most critical shortcoming of magnesium alloys from the point of view of medical devices is the high corrosion rate, which is not well-correlated with clinical needs. It is well- known that rapid degradation occurs when an implant made of Mg-based alloys is placed inside the human body. Consequently, the implant loses its mechanical properties and failure can occur even if it is not completely degraded. The corrosion products that appear after Mg-based alloy degradation, such as H2 and OH- can have an essential role in decreasing biocompatibility due to the H2 accumulation process in the tissues near the implant. In order to control the degradation process of the Mg-based alloys, different coatings could be applied. The aim of the current paper is to evaluate the effect of fluoride coatings on the corrosion behavior of magnesium alloys from the system Mg-Zn-Ca-Mn potentially used for orthopedic trauma implants. The main functional properties required for the magnesium alloys to be used as implant materials, such as surface properties and corrosion behavior, were studied before and after surface modifications by fluoride conversion, with and without preliminary sandblasting, of two magnesium alloys from the system Mg-Zn-Ca-Mn. The experimental results showed that chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental magnesium alloys from the Mg-Zn-Ca-Mn system. Also, high surface free energy values obtained for the alloys treated with hydrofluoric acid correlated with wettability lead to the conclusion that there is an increased chance for biological factor adsorption and cell proliferation. Chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental Mg-Zn-Ca-Mn alloys.

Corrosion and Mechanical Behavior of the As-Cast and Solid-Solution-Treated AM50 Magnesium Alloy in Different Media

Hydrogen embrittlement and the anodic dissolution mechanism are two important aspects of the corrosion behavior of magnesium alloys. Here, to evaluate the effects of these two aspects on the corrosion failure of magnesium alloys under stress, the stress and corrosion behaviors of the AM50 magnesium alloy in air, deionized water, and NaCl solution after solid-solution (T4) treatment were investigated by X-ray diffraction, scanning electron microscopy, slow strain rate tensile testing, and vacuum dehydrogenation. The as-cast AM50 magnesium alloy was mainly composed of the α-Mg and β-Mg17Al12 phases. After T4 treatment, the amount of the β-Mg17Al12 phase was significantly reduced, and only a small amount existed at the grain boundaries. After T4 treatment, the stress corrosion resistance in deionized water improved, but it decreased in an NaCl environment. Dehydrogenation experiments showed that the effect of hydrogen on the corrosion process was weakened owing to the decrease of the β-Mg17Al12 phase after solution treatment. The effects of hydrogen embrittlement and the anodic dissolution mechanism on the corrosion behavior of the AM50 magnesium alloy under stress were different. In deionized water, the hydrogen embrittlement mechanism played the major role, while the anodic dissolution mechanism played the major role in the presence of Cl- ions.

Effect of volume fraction of 18R-LPSO phase on corrosion resistance of Mg−Zn−Y alloys

This study aims to elucidate the effect of LPSO phases on the corrosion behavior of magnesium alloys through experimental design. The microstructure and corrosion behavior of four Mg−Zn−Y alloys designed according to the minimum structural unit for forming the 18R-LPSO phase, i.e. Zn/Y=3/4 (molar ratio), were studied in a comparative manner. The results showed that the alloys mainly contained α-Mg and 18R-LPSO phases, and the volume fraction of the 18R-LPSO phase increased with the increase of Zn and Y contents. The volume fraction of the 18R-LPSO phase in the four alloys was, in sequence, 16.55%, 34.45%, 54.24% and 70.36%, and the spatial distribution of the 18R-LPSO phase also changed from discrete blocks to continuous networks. When the volume fraction was about 50%, the corrosion resistance of the alloy was the best. When the volume fraction was greater than or less than 50%, the corrosion resistance of the alloy decreased.

Microgalvanic corrosion mechanism of the rare-earth phase in Mg binary alloys through first-principles calculation

In this study, we examined the influence mechanism of heavy rare-earth elements Gd and Y on the corrosion behavior of magnesium alloys by combining experimental characterization with the first-principles calculation. We investigated the changes in the work function and surface energies of the second rare-earth phase and matrix phase in binary rare-earth magnesium alloys, Mg-3.5%Gd and Mg-3.5%Y. In addition, we focused on determining the electronic properties of the second rare-earth phase and matrix phase, the correlation between the interface energy of both phases, and the corrosion behavior of the magnesium alloys. The experimental results show Mg3Gd and Mg24Y5 as the second phases of Mg-3.5%Gd and Mg-3.5%Y, respectively; these have different roles in the galvanic corrosion of the alloys. That is, Mg3Gd is the cathode phase, which promotes the corrosion of the surrounding matrix, while Mg24Y5 dissolves itself as the anode phase in the corrosion process. The results of the first-principles calculation show that the work function of the second phase in the alloy is higher than that of the Mg matrix phase doped with rare earth. Moreover, the work function of each crystal plane of the Mg3Gd phase is generally higher than that of Mg24Y5. This implies that the corrosion rate of Mg-3.5%Y is faster than that of Mg-3.5%Gd. The corrosion law obtained through an electrochemical test and a scanning Kelvin probe force microscope test is consistent with the work function calculation results. The calculation results of interface energy show that the interface between Mg3Gd and the matrix is more stable than that between Mg24Y5 and the matrix. In addition, the galvanic corrosion between Mg24Y5 and the matrix is stronger. This result reaffirms the higher corrosion rate of Mg-3.5%Y over that of Mg-3.5%Gd.

Bioinspired Surface Design for Magnesium Alloys with Corrosion Resistance

Magnesium alloys are regarded as potential candidates in industrial and biomedical applications because of their excellent mechanical properties and biodegradability. However, the excessive degradation rate of magnesium alloys can cause a premature disintegration of mechanical integrity, which is the main bottleneck that limits applications. Inspired by nature, various novel surface designs provide a clever strategy to regulate the corrosion behavior of magnesium alloys. This review extensively discusses bioinspired surface designs to reduce corrosion resistance and realize functionalization, so as to offer new ideas with great potential for biomedical applications. Future research on corrosion resistance is expected to benefit greatly from the bioinspired surface designs.

Improving the corrosion behavior of magnesium alloys with a focus on AZ91 Mg alloy intended for biomedical application by microstructure modification and coating.

Magnesium alloys such as AZ91 have received much attention due to their attractive properties, including biocompatibility and lightness. Although magnesium is a potential candidate for implant application, due to its rapid degradation in the physiological environment, there are still some challenges to using it as biocompatible implants. In this regard, various techniques such as microstructure modification and coating are utilized to moderate the degradation rate of magnesium alloys. Therefore, efforts are being made to conduct more extensive research to produce magnesium implants with acceptable corrosion resistance. In this literature review, an overview of the history of research on the corrosion behavior, biodegradability, microstructure deformation mechanisms, crystallographic texture in magnesium alloys with a focus on AZ91 Mg alloy, is provided. In addition, the necessity of improving the properties of AZ91 Mg alloy by the two methods of improving microstructure and coating, and existing innovations in these methods are investigated.

Effect of ZrSiO4 Concentration on the Microstructure and Corrosion Resistance of MAO Coatings Formed on AZ91 Magnesium Alloy

As a metallic material with lightweight and high specific strength, magnesium alloy has excellent application prospects. However, the rapid corrosion rate and localized corrosion behavior of magnesium alloys limit the practical application in the automobile industry. In this study, to improve the corrosion resistance of AZ91 alloy, the film of different concentrations containing zirconium (AZR0, AZR5, AZR10, AZR15) was prepared on the surface of AZ91 alloy by micro-arc oxidation technology in the Na2SiO3-Na3PO4 system. Furthermore, the influence of electrolyte composition on the corrosion resistance of the MAO film was systematically investigated. The experimental results revealed that the ZrSiO4 particles added in the electrolyte could enter into the MAO film and ZrSiO4 particles were also decomposed into ZrO2 and Mg2Zr5O11 in the process of micro-arc oxidation. More importantly, the formation of micro-cracks and other defects in the film could be reduced after this process. The addition of 15 g l−1 ZrSiO4 in the electrolyte was contributed to the best comprehensive properties of MAO-processed AZ91 specimens, including improved Vickers hardness of 167.16 Hv, Young’s modulus of 652 MPa, and enhanced corrosion resistance (RP = 9.82 × 105 Ω cm2). This approach could provide the approach for developing Mg-based materials with high anticorrosion in industrial fields.

In silico modelling of the corrosion of biodegradable magnesium-based biomaterials: modelling approaches, validation and future perspectives.

ABSTRACTMetallic biomedical implants based on magnesium, zinc and iron alloys have emerged as bioresorbable alternatives to permanent orthopaedic implants over the last two decades. The corrosion rate of biodegradable metals plays a critical role in controlling the compatibility and functionality of the device in vivo. The broader adoption of biodegradable metals in orthopaedic applications depends on developing in vitro methods that accurately predict the biodegradation behaviour in vivo. However, the physiological environment is a highly complex corrosion environment to replicate in the laboratory, making the in vitro-to-in vivo translation of results very challenging. Accordingly, the results from in vitro corrosion tests fail to provide a complete schema of the biodegradation behaviour of the metal in vivo. In silico approach based on computer simulations aim to bridge the observed differences between experiments performed in vitro and vivo. A critical review of the state-of-the-art of computational modelling techniques for predicting the corrosion behaviour of magnesium alloy as a biodegradable metal is presented.

Effect of Surface Roughness Induced by Milling Operation on the Corrosion Behavior of Magnesium Alloys

Effect of Surface Roughness Induced by Milling Operation on the Corrosion Behavior of Magnesium Alloys

Long-Term Corrosion Behavior of AZ80 Magnesium Alloy along Different Crystallographic Orientations in Simulated Body Fluid

Two orientation samples were prepared along the normal (ND) and transverse (TD) directions of the rolled AZ80 magnesium alloy. The samples (ND and TD) were immersed in simulated body fluid (SBF) for long-term (25 days) immersion test. Electrochemical measurements such as electrochemical impedance spectroscopy and potentiodynamic polarization test were conducted to study the electrochemical behavior. Scanning electron microscopy and energy-dispersive x-ray spectrometer were used to investigate the corrosion morphology and chemical composition of samples during various immersion processes. X-ray diffraction was employed to identify the texture composition. The results indicated that severe localized corrosion occurred in the ND sample. Uniform corrosion was the dominant corrosion in the TD sample. The TD sample exhibited better corrosion performance (higher corrosion resistance and lower corrosion rate) than the ND sample. The corrosion behavior of magnesium alloy was closely related to texture, microstructure, and corrosion product film. The influence mechanism of texture and microstructure on corrosion behavior of magnesium alloy was discussed.

Measurement of corrosion behaviour of magnesium alloys developed for application in biomaterials area

Measurement of corrosion behaviour of magnesium alloys developed for application in biomaterials area

Effects of zirconium addition on electrochemical and mechanical properties of Mg-3Zn-1Ca-1RE alloy

Purpose The effect of zirconium, zinc, calcium and rare earth group as the alloying elements on mechanical properties and corrosion behavior of magnesium alloys was investigated in the simulated body fluid. Design/methodology/approach Pure magnesium and the alloying elements were melted and zirconium was finally added to obtain different alloys. The castings were annealed and some samples were aged heat treated. X-ray fluorescence was used for the elemental analysis and LSV was used for electrochemical corrosion evaluations. Findings Results showed that corrosion resistance decreases with increasing zirconium content. The lowest corrosion rate was obtained for the samples containing 0.3% and 0.45% of Zr from annealed and aging heat-treated samples, respectively. Yield stress enhances with increasing the zirconium content and degrades by the aging heat treatment. Originality/value These alloys were studied for the first time. Effect of casting without using protective flux and vacuum furnaces. Effect of annealing at 440°C for 2 h and artificial aging at 200°C for 16 h. Alloy’s electrochemical behavior on the body’s simulation environment has been investigated. Improvement of mechanical properties after annealing heat treatment by high zirconium percentage.

Dynamic corrosion behavior of AZ80 magnesium alloy with different orientations in simulated body fluid

Two specimens were prepared along the normal (ND) and transverse (TD) directions of the AZ80 magnesium alloy rolled sheet, respectively, and the other specimen was prepared along the normal direction at 45° (ND45). Three specimens (ND, ND45 and TD) were immersed in dynamic immersion equipment for in-situ electrochemical test. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the static and dynamic corrosion behavior of the specimens in simulated body fluid (SBF). The results indicated that the specimens with different orientations exhibited anisotropy of corrosion performance. The electrochemical corrosion resistance of the specimens decreased in the following order: TD > ND45 > ND. The electrochemical corrosion resistance of the specimens decreased with increasing flow rate. The specimens immersed in SBF solution suffered localized corrosion, and the corrosion degree at the edge position of the specimen was higher than that at the middle position in dynamic environment. Computational fluid dynamics (CFD) simulations showed that with the increase of flow rate, the increase of shear stress and mass transfer coefficient led to the intensification of localized corrosion. The effect of initial texture and flow rate on the corrosion behavior of magnesium alloy was discussed.

The corrosion behavior of Mg-9Al-xRE magnesium alloys modified by friction stir processing

The combination of rare earth (RE) alloying and friction stir processing (FSP) was demonstrated to be favorable in improving the corrosion resistance of Mg-9Al alloys. The microstructure and corrosion behavior of the modified Mg-9Al-xRE alloys were documented in this paper. Electrochemical measurements revealed that the corrosion resistance of as-cast Mg-9Al-xRE alloys in 3.5 wt% NaCl solution was weaken with the addition of RE elements. It is found that the formation of a large amount of coarse strip-like Al-RE precipitates is responsible for the accelerated dissolution of anodic magnesium matrix. However, the corrosion resistance of FSPed Mg-9Al-xRE alloys was improved when the RE element was added and the improvement was further enhanced with the increasing amount of RE addition. This is mainly attributed to the alternation in the corrosion behavior of magnesium alloys owing to the refined and redistributed precipitates in α-Mg matrix. The refinement of cathodic precipitates enlarges the local area ratio of anode and cathode and retards the severe galvanic corrosion tendency in magnesium alloys. In addition, the presence of a large amount of fine Al-RE precipitates is favorable in accumulative growing of the corrosion product layer during the corrosion propagation, and thus improves the stability and compactness of this protective layer.

Synergistic Action of Sulfate and Chloride Anions on the Corrosion Behavior of AZ31B Magnesium Alloy

Magnesium and its alloys have a great potential for lightweight structure applications, because magnesium has lower density (~1.7 g.cm-3) compared to aluminum (2.7 g.cm-3) and iron (~7.9 g.cm-3). Magnesium alloys also exhibit high strength-to-weight ratios [1]. Their use enables the weight reduction of automotive and aerospace vehicles for more energy consumption efficient. However, magnesium alloys have a limitation for practical application, namely the high chemical activity, porous corrosion product and high corrosion rate. In addition, due to the rapid industrialization in some developing countries, air pollution (like PM2.5) has become a hot topic. Most of air pollutants contain ions like SO4 2-, NO3- and NH4+, which have high solubility [2]. The corrosion behavior of magnesium in chloride-containing environment is also worth studying because Cl- is the most common aggressive corrosion species. In contrast, sulfate ions in chloride-containing solutions can inhibit hydrogen evolution [3]. It is thus of great interest to understand the corrosion behavior of magnesium alloys in solution containing different anions, which provides a basis for designing the effective conversion coating process.In this study, the corrosion behavior of magnesium alloy AZ31B in sulfate and chloride solutions was investigated by using real-time imaging, hydrogen evolution test, electrochemical analysis, and cross-sectional TEM characterization. Through the results of the real-time imaging, the corrosion behavior of magnesium alloy AZ31B in the solution can be roughly divided into three stages. Firstly, the uniform corrosion proceeds with a large amount of hydrogen evolution. Secondly, the corrosion product gets thicker accompanied by the reduction in the amount of hydrogen evolution. Final stage only happens in the chloride containing solution. A hydrogen stream and dark corrosion products are produced [4]. Cross-sectional TEM was employed to characterize the sample, which was immersed for 25 min (the time when the dark corrosion product was produced). The results show that when the magnesium alloy AZ31B was treated in the chloride solution, the thickness of the corrosion product layer is about 80 ± 30 nm. Furthermore, the corrosion product layer formed in a sulfate-containing solution shows a uniform film thickness about 170 nm. This difference in thickness was further confirmed in the hydrogen evolution test. The hydrogen evolution test shows that the amount of hydrogen produced by the magnesium alloy AZ31B in the sulfate solution is about twice that in the chloride solution. This indicates that the corrosion product formed in the sulfate solution is about twice that in the chloride solution, implying that the corrosion product formed in the chloride ion environment is more protective. The EIS results also show the same trend. The total impedance of the corrosion product in the chloride ion immersion environment is much larger than that of the sulfate solution and the total impedance value increases as the chloride concentration is increased. As a result, chloride ions can effectively fill the weaker areas of the airform film during the early stages of corrosion. This localized corrosion phenomenon also causes the difference in film thickness.The third stage of corrosion was found to be absent when the magnesium alloy AZ31B was immersed in a chloride and sulfate mixture solution. The TEM results show that the corrosion product is more uniform than immersed in solution containing only chloride. Thus, it is proposed that sulfate ions serve as a physical barrier to hinder chlorine ions from attacking the magnesium substrate, which, in turn, results in a uniform corrosion product layer.