Corrosion Properties Of Mg Research Articles

Influence of temperature and number of passes during twist channel angular pressing (TCAP) on the microstructural, mechanical, and corrosion properties of Mg–4Li–Ca

Influence of temperature and number of passes during twist channel angular pressing (TCAP) on the microstructural, mechanical, and corrosion properties of Mg–4Li–Ca

Mechanical and Corrosion Properties of Mg–Gd–Cu–Zr Alloy for Degradable Fracturing Ball Applications

Generally, excellent mechanical properties of Mg alloys are desired, but their rapid degradation properties are seldom utilized. Petroleum fracturing techniques are required to take full advantage of this rapid degradation. Therefore, we have prepared an as-extruded Mg–6.0Gd–1.2Cu–1.2Zr (wt.%) alloy and treated it with peak aging to analyze its potential as a degradable fracture ball. The results show that the as-extruded alloy mainly consists of an α-Mg matrix, second phase, and large elongated α-Mg grains (LEGs). After aging, the LEGs undergo static recrystallization, which improves the mechanical properties of the alloy, and a lamellar long period stacking ordered (LPSO) phase is observed. Under simulated underground temperature conditions (93 °C), the ultimate tensile strength and elongation of both as-extruded and as-aged alloys are over Ȧ MPa and 11.1%, respectively, and the ultimate compressive strength and elongation of both alloys are over 336 MPa and 16.9%, respectively. The corrosion rate of the as-extruded alloy in 3 wt.% KCl solution at 93 °C reaches 1660.8 mm/y by mass loss test, and that of the as-aged alloy increases to 1955.1 mm/y. The atomic force microscope analysis result confirms that the second phase shows the highest corrosion potential, followed by the lamellar LPSO phase and α-Mg matrix. The as-extruded and as-aged Mg–6.0Gd–1.2Cu–1.2Zr alloy with good mechanical properties and a high corrosion rate in this work shows promising potential for degradable fracturing ball applications.

Mechanical and corrosion properties of Mg–MgO and Mg–Al2O3 composites fabricated by equal channel angular extrusion method

Equal channel angular extrusion (ECAE) has shown great potential for the consolidation of powdered materials. In the present article, the mechanical and corrosion properties of Mg–MgO and Mg–Al 2 O 3 composites produced by the ECAE method were studied. Pure magnesium reinforced with 0, 10, 20, and 30 ​vol percentages of MgO and Al 2 O 3 particles were hot consolidated at 600 ​MPa in an ECAE die without prior cold compaction or canning of the powders. Results indicated that the reinforcement content is directly proportional to the hardness, compressive strength, and corrosion resistance of the fabricated composites, while it has an inverse relationship with the relative density. The lowest relative density and the highest corrosion rate were obtained for the Mg+30%MgO composite samples, as opposed to the pure magnesium with the highest relative density and the lowest corrosion rate. Besides, composites reinforced with 30 and 20 ​vol percentages of alumina revealed the highest hardness and the highest compressive strength, which were 55% and 74% higher than that of the pure magnesium sample, respectively. Based on SEM and EDX analyses, it was shown that Mg–Al 2 O 3 samples had finer grain sizes compared to Mg–MgO composites. • ECAE was successfully implemented to fabricate Mg–MgO and Mg–Al 2 O 3 composites. • Hardness and strength are linearly related to the content of the reinforcements. • Mg–Al 2 O 3 showed remarkably higher strength and hardness compared to the Mg–MgO. • The corrosion rate of the Mg–Al 2 O 3 was lower than that of Mg–MgO.

Corrosion behavior of severely plastically deformed Mg and Mg alloys

Magnesium (Mg) alloys have several advantages, such as low density, high specific strength and biocompatibility. However, they also suffer weak points, such as high corrosion, low formability and easy ignition, which makes their applications limited. Many studies have been conducted to overcome these disadvantages and further improve the advantages of Mg alloys. Severe plastic deformation (SPD) is one of the most important techniques and has great effects on the microstructure refinement of Mg alloys and improvements in their strength and formability. Several researchers have studied the corrosion behavior of SPD-processed Mg alloys in recent decades. However, these studies have reported some controversial effects of SPD on the corrosion of Mg alloys, which makes the research roadmap ambiguous. Therefore, it is important to review the literature related to the corrosion properties of Mg alloys prepared by SPD and understand the mechanisms controlling their corrosion behavior. Effective grain refinement by SPD improves the corrosion properties of pure Mg and Mg alloys, but control of the processing conditions is a key factor for achieving this goal because texture, dislocation density, size and morphology of secondary phase also importantly affects the corrosion properties of Mg alloys. Reduced grain size in the fine grain-size range can decrease the corrosion rate due to the increased barrier effect of grain boundaries against corrosion and the formation of a stable passivation layer on the surface of fine grains. Basal texture reduces the corrosion rate because basal planes with the highest atomic planar density are more corrosion resistant than other planes. Increased dislocation density after SPD deteriorates the corrosion resistance of the interior grains and thus proper annealing after SPD is important. The fine and uniform distribution of secondary phase particles during SPD is important to minimize the micro-galvanic corrosion effect and retain small grains during annealing treatment for removing dislocations.

Effect of Ag Addition on Microstructure, Mechanical and Corrosion Properties of Mg–Nd–Zn–Zr Alloy for Orthopedic Application

Effect of Ag Addition on Microstructure, Mechanical and Corrosion Properties of Mg–Nd–Zn–Zr Alloy for Orthopedic Application

Corrosion properties of ECAP-processed Mg−Al−Ca−Mn alloys with separate Al2Ca and Mg2Ca phases

To investigate the effect of separate Al2Ca and Mg2Ca phases on the corrosion properties of Mg−Al−Ca−Mn alloys, OM, SEM, immersion and electrochemical tests were conducted on the as-cast and ECAP Al2Ca-containing (2Ca) and Mg2Ca-containing (4Ca) alloys. At the beginning of corrosion, the two as-cast alloys are corroded slowly compared with ECAP alloys. With prolonging the corrosion time, the corrosion of ECAP alloys becomes slighter than that of as-cast alloys, which is mainly ascribed to the dispersion and refinement of the second phase in ECAP alloys. Moreover, the corrosion degree of 2Ca alloys is always slighter than that of 4Ca alloys, suggesting that Al2Ca phase is more beneficial to the enhancement of corrosion resistance of Mg−Al−Ca−Mn based alloys than Mg2Ca phase. Finally, based on the examinations of corrosion surface and electrochemical testing results, different corrosion mechanisms caused by the distributions and morphology of Al2Ca and Mg2Ca phases are discussed.

Mechanical and corrosion properties of graphene nanoplatelet–reinforced Mg–Zr and Mg–Zr–Zn matrix nanocomposites for biomedical applications

Magnesium (Mg)-based biomaterials have gained acceptability in fracture fixation due to their ability to naturally degrade in the body after fulfilling the desired functions. However, pure Mg not only degrades rapidly in the physiological environment, but also evolves hydrogen gas during degradation. In this study, Mg0.5Zr and Mg0.5ZrxZn (x = 1–5 wt.%) matrix nanocomposites (MNCs) reinforced with different contents (0.1–0.5 wt.%) of graphene nanoplatelets (GNP) were manufactured via a powder metallurgy technique and their mechanical and corrosion properties were evaluated. The increase in GNP concentration from 0.2 wt.% to 0.5 wt.% added to Mg0.5Zr matrices resulted in decreases in the compressive yield strength and corrosion resistance in Hanks’ Balanced Salt Solution (HBSS). On the other hand, a higher concentration (4–5 wt.%) of Zn added to Mg0.5Zr0.1GNP resulted in an increase in ductility but a decrease in compressive yield strength. Overall, an addition of 0.1 wt.% GNPs to Mg0.5Zr3Zn matrices gave excellent ultimate compressive strength (387 MPa) and compressive yield strength (219 MPa). Mg0.5Zr1Zn0.1GNP and Mg0.5Zr3Zn0.1GNP nanocomposites exhibited 29% and 34% higher experimental yield strength, respectively, as compared to the theoretical yield strength of Mg0.5Zr0.1GNP calculated by synergistic strengthening mechanisms including the difference in thermal expansion, elastic modulus, and geometry of the particles, grain refinement, load transfer, and precipitation of GNPs in the Mg matrices. The corrosion rates of Mg0.5Zr1Zn0.1GNP, Mg0.5Zr3Zn0.1GNP, Mg0.5Zr4Zn0.1GNP, and Mg0.5Zr5Zn0.1GNP measured using potentiodynamic polarization were 7.5 mm/y, 4.1 mm/y, 6.1 mm/y, and 8.0 mm/y, respectively. Similarly, hydrogen gas evolution tests also demonstrated that Mg0.5Zr3Zn0.1GNP exhibited a lower corrosion rate (1.5 mm/y) than those of Mg0.5Zr1Zn0.1GNP (3.8 mm/y), Mg0.5Zr4Zn0.1GNP (1.9 mm/y), and Mg0.5Zr5Zn0.1GNP (2.2 mm/y). This study demonstrates the potential of GNPs as effective nano-reinforcement particulates for improving the mechanical and corrosion properties of Mg–Zr–Zn matrices.

Effect of Heat Treatment on the Mechanical and Corrosion Properties of Mg-Zn-Ga Biodegradable Mg Alloys.

Mg alloys have mechanical properties similar to those of human bones, and have been studied extensively because of their potential use in biodegradable medical implants. In this study, the influence of different heat treatment regimens on the microstructure and mechanical and corrosion properties of biodegradable Mg–Zn–Ga alloys was investigated, because Ga is effective in the treatment of disorders associated with accelerated bone loss. Solid–solution heat treatment (SSHT) enhanced the mechanical properties of these alloys, and a low corrosion rate in Hanks’ solution was achieved because of the decrease in the cathodic-phase content after SSHT. Thus, the Mg–4 wt.% Zn–4 wt.% Ga–0.5 wt.% Y alloy after 18 h of SSHT at 350 °C (ultimate tensile strength: 207 MPa; yield strength: 97 MPa; elongation at fracture: 7.5%; corrosion rate: 0.27 mm/year) was recommended for low-loaded orthopedic implants.

On the effect of compaction velocity, size, and content of reinforcing particles on corrosion resistance of Mg–B4C composites

In this study, the effect of the compaction velocity as well as the size and volume fraction of the reinforcing particles on the corrosion properties of Mg–B4C composites were investigated. Micron/nano particles of boron carbide at different volume fractions (0, 5, and 10%) were added to the matrix (magnesium powder). Powder mixtures were milled in a planetary ball mill and compacted at 450 °C and different strain rates, using Split-Hopkinson bar (SHB), drop hammer, and Instron devices. Microstructural analysis and corrosion tests were carried out on the produced samples. The results indicated that the samples produced at higher compaction velocities had the lower corrosion rate mainly due to the lower porosity and higher relative density of the samples. For example, the measured corrosion rates for the magnesium samples reinforced with 5 vol% of micron B4C particles and compacted by the SHB method were 54 and 76% lower than the similar samples produced by the drop hammer and Instron device, respectively. It was also shown that decreasing the size and content of the reinforcing particles resulted in a reduction in the corrosion rate values. The recorded corrosion rate values for the samples reinforced with 5 and 10 vol% of B4C nanoparticles and compacted by the drop hammer device were 18.3 and 29.18 mm/year, respectively. These valuses were approximately 16 and 13% lower compared to the similar composites reinforced with micron-sized particles. The lowest corrosion rate (1.84 mm/year) was observed in the pure magnesium sample compacted by the SHB which was 29.42% lower than that of the magnesium sample reinforced with 10 vol% of micron-sized B4C.

Tailoring surface characteristics of bioabsorbable Mg-Zn-Dy alloy using friction stir processing for improved wettability and degradation behavior

Magnesium (Mg) and its alloys are currently under consideration for use as temporary implants. However, early degradation and maintaining mechanical integrity is a significant concern. Surface modification techniques are used to improve mechanical and corrosion properties of Mg based alloys. In the present study, friction stir processing (FSP) was used to tailor the surface characteristics of Mg-1Zn-2Dy (wt.%) alloy for temporary implant applications. The FSPed alloy was characterized using EBSD to understand the influence of FSP on crystallographic texture, grain size and grain boundaries and thereby their effect on corrosion, wettability and hardness. Results showed that the grain size of stir zone (SZ) was refined to less than 3 μm, as a result of dynamic recrystallization (DRX) during FSP and the FSPed alloy exhibited better wettability than as-cast alloy. An increase in the hardness (11.7%) and elastic modulus (6.84%) of FSPed alloy were also observed. Electrochemical corrosion and weight loss methods were conducted in Dulbecco's Modified Eagle's Medium (DMEM) with, 10% Fetal Bovine Serum (FBS) physiological solution. The lower degradation rate (0.72 mm/yr) of FSPed alloy has been attributed to the fine grains and evenly distributed secondary phase particles. Further, the influence of grain boundary characteristics and crystallographic texture on the corrosion behavior have been investigated.

Microstructure, mechanical and corrosion properties of Mg–Zn–Sr–Ca alloys for use as potential biodegradable implant materials

ABSTRACT Effects of Ca addition on as-cast microstructure, mechanical and corrosion properties of Mg–2Zn–0.3Sr alloy were investigated for biodegradable implant application. First, a comparison between Ca and Sr addition in Mg–2Zn alloy was studied. Mg–2Zn–0.3Sr showed the better corrosion performance, but the worse mechanical property. Then, the results of Ca addition indicated that the dendritic phases dispersed in the Mg matrix. The grains became smaller as Ca content increased. The ultimate tensile strength of Mg–2Zn–0.3Sr–0.3Ca alloy was strengthened to about 170MPa, along with a good ductility of 10%, due to the refinement of grains and homogenous morphology. The ternary alloy had the lowest degradation rate. Mg–2Zn–0.3Sr–0.3Ca still presented a considerable corrosion resistance. 0.5wt% Ca addition brought more and coarser second phases, and worse mechanical and corrosion property. It is suggested that minor addition of Ca (0.1–0.3wt%) in Mg–2Zn–0.3Sr alloy would benefit the practical performance for use in biodegradable implants.

Microstructure, mechanical and corrosion properties of Mg–Zn–Nd alloy with different accumulative area reduction after room-temperature drawing

Good mechanical properties and corrosion resistance are the key factors for the application of biodegradable magnesium alloy wires as new medical implant materials. This study is aimed at investigating the influence of microstructural evolution on mechanical and corrosion properties of Mg–2Zn–0.5Nd alloy (ZN20) during room-temperature drawing. The decreases in the cross-sectional area of ZN20 alloy during drawing refined the grains from 10 to 5 μm under the influence of cold deformation, the basal texture was rotated around radius direction, the basal texture became dominant, and the texture transformed from drawing direction (DD)// $$ $$ to a point between $$ $$ and $$ $$ parallel to DD. The ultimate tensile strength of the wire was increased by 44.7% compared with that of the extruded alloy due to grain boundary strengthening, hard orientation and work hardening during drawing process, while the elongation was decreased by 85% under the influence of work hardening. The corrosion resistance of the alloy was improved after drawing due to grain refinement, while it was sensitive to prismatic texture.

Microstructure and corrosion properties of Mg–0.5Zn–0.2Ca–0.2Ce alloy with different processing conditions

The microstructure and corrosion resistance of Mg–0.5Zn–0.2Ca–0.2Ce alloy with different processing conditions were investigated. The composition was detected by X-ray fluorescence (XRF), and the microstructure was analyzed by optical microscopy (OM) and scanning electron microscope (SEM) equipped with energy-dispersive spectroscopy (EDS). The corrosion behavior was investigated by hydrogen evolution tests, weight loss tests and electrochemical measurements. The Mg–0.5Zn–0.2Ca–0.2Ce alloy has much better corrosion resistance compared with the commercial AZ31 sheet, which can be attributed to its dispersive second phases and protective corrosion products film on the alloy surface. Moreover, the as-rolled Mg–0.5Zn–0.2Ca–0.2Ce alloy shows much better corrosion resistance compared with the as-extruded Mg–0.5Zn–0.2Ca–0.2Ce alloy. This can be due to three aspects: The as-rolled alloy has smaller grain size; the as-rolled alloy has lower (10 $${\bar{1}}$$ 0)/(11 $${\bar{2}}$$ 0) texture intensity; the residual stress of the as-rolled alloy is eliminated during the annealing process, but large residual stress exists in the as-extruded alloy produced by the extrusion process.

Effect of Y addition on microstructure and corrosion behavior of extruded Mg–Zn–Nd–Zr alloy

Abstract In this study, the effect of Y addition (0, 0.5, 1 and 2 wt%) on microstructure and corrosion properties of Mg–6Zn–0.5Zr–1Nd (wt%) alloy was investigated. The alloys were produced by low-pressure die casting method and extruded at 300 °C and 400 °C after homogenization treatment at 400 °C for 24 h. The results showed that the as-cast microstructure of the alloy with no Y addition consisted of α-Mg, Mg–Zn binary and Mg–Zn–Nd ternary phases. With increasing Y additions, the average grain size showed a substantial decrease and two kinds of ternary Mg–Zn–Y ternary phases, designated as I-phase (Mg3Zn6Y) and W-phase (Mg3Zn3Y2) were formed. Homogenization treatment resulted in a partial dissolution of second phase particles. Extrusion process gave rise to a remarkable grain refinement due to the DRX mechanism. The extruded alloys with no Y addition exhibited poor corrosion resistance due to the strong micro galvanic coupling effect. Y additions up to 1 wt% improved the corrosion resistance due to the formation of finer grains, fine and uniform distribution of second phase particles and more stable oxide film.

Mechanical, corrosion and biological properties of advanced biodegradable Mg–MgF2 and WE43-MgF2 composite materials prepared by spark plasma sintering

Newly developed magnesium composite materials with a continuous network of MgF2 prepared by powder metallurgy exerted enhanced corrosion resistance and seems to be suitable for application in medicine as biodegradable implants. In this work, the influence of conditions of preparation of Mg and WE43 composite materials on final mechanical and corrosion properties of spark plasma sintered samples is revealed. Immersion in HF leads to the significant improvement of corrosion properties of Mg and WE43, while mechanical properties of WE43 alloy are reduced due to the specific interface. Moreover, cytocompatibility tests revealed the nontoxic behavior of magnesium fluoride coating on both Mg and WE43 alloy. The better proliferation of cells was observed on the WE43 composite material.

Processing and understanding of light-weight Mg-4Li-xCa (0, 0.5 and 1) alloy for bio-degradable implant applications

Magnesium alloy is the promising candidate for biodegradable implants because of its low density, and corrosion products do not cause any toxicity to the human body. However, its poor formability in room temperature and poor corrosion resistance limit its applications. Therefore, efforts have been made to improve the formability and corrosion properties of Mg by adding lithium (Li) and calcium (Ca) as alloying elements. The Mg-4Li-xCa alloy’s microstructure, mechanical properties and corrosion behaviour with varying calcium content (0, 0.5 and 1.0) were systematically studied. The microstructure of the Mg-Li alloy shows α-Mg matrix whereas Mg-Li −0.5 Ca and Mg-4Li-1Ca exhibits eutectic phase (α-Mg + Mg2Ca) along with α-Mg. The Mg-4Li alloy displays good mechanical properties upon increasing Ca addition. The bio-corrosion behaviour of the Mg alloys are determined by electrochemical polarization test. The results show that the after Ca addition Mg-4Li alloys shows better corrosion resistance.

Effects of Solution Treatment on Corrosion Properties of Mg–6 mass%Al–1 mass%Zn–2 mass%Ca (AZX612) and Mg–6 mass%Al–1 mass%Zn (AZ61) Alloys

Effects of Solution Treatment on Corrosion Properties of Mg–6 mass%Al–1 mass%Zn–2 mass%Ca (AZX612) and Mg–6 mass%Al–1 mass%Zn (AZ61) Alloys

Effect of Solution Treatment on Microstructure and Corrosion Properties of Mg–4Gd–1Y–1Zn–0.5Ca–1Zr Alloy

The as-cast multi-element Mg–4Gd–1Y–1Zn–0.5Ca–1Zr alloy with low rare earth additions was prepared, and the solution treatment was applied at different temperatures. The microstructural evolution of the alloy was characterized by optical microscopy and scanning electron microscopy, and corrosion properties of the alloy in 3.5% NaCl solution were evaluated by immersion and electrochemical tests. The results indicate that the as-cast alloy is composed of the α-Mg matrix, lamellar long-period stacking-ordered (LPSO) structure and eutectic phase. The LPSO structure exists with more volume fraction in the alloy solution-treated at 440 °C, but disappears with the increase in the solution temperature. For all the solution-treated alloys, the precipitated phases are detected. The corrosion rates of the alloys decrease first and then increase slightly with the increase in the solution temperature, and the corrosion resistance of the solution-treated alloys is more than four times as good as that of the as-cast alloy. In addition, the alloy solution-treated at 480 °C for 6 h shows the best corrosion property.

Microstructure and corrosion study of porous Mg–Zn–Ca alloy in simulated body fluid

Magnesium alloys had been considered as promising biomedical devices due to their biocompatibility and biodegradability. In this present work, microstructure and corrosion properties of Mg–Zn–Ca–CaCO3 porous magnesium alloy were examined. Porous metals were fabricated through powder metallurgy process with CaCO3 addition as a foaming agent. CaCO3 content was varied (1, 5, and 10%wt) followed by sintering process in 650 °C in Argon atmosphere for 10 and 15 h. The microstructure of the resulted alloys was analyzed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry data (EDS). Further, to examine corrosion properties, electrochemical test were conducted using G750 Gamry Instrument in accordance with ASTM standard G5-94 in simulated body fluid (Hank’s solution). As it was predicted, increasing content of foaming agent was in line with the increasing of pore formation. The electrochemical testing indicated corrosion rate would increase along with the increasing of foaming agent. The porous Mg–Zn–Ca alloy which has more porosity and connecting area will corrode much faster because it can transport the solution containing chloride ion which accelerated the chemical reaction. Highest corrosion resistance was given by Mg–Zn–Ca–1CaCO3-10 h sintering with potential corrosion of −1.59 VSCE and corrosion rate of 1.01 mmpy. From the microstructure after electrochemical testing, it was revealed that volcano shaped structure and crack would occur after exposure to Hank’s solution

Influence of Gd and Ca on microstructure, mechanical and corrosion properties of Mg–Gd–Zn(–Ca) alloys

Microstructures, mechanical and corrosion properties of the Mg–xGd–1Zn (x=3, 6, and 9 wt%) and Mg–9Gd–1Zn–yCa (y=0, 0.2, and 0.6 wt%) alloys were studied and compared for biomedical applications. The results show that the microstructures of the alloys are composed of primary α-Mg, eutectic phase, lamellar long period stacking ordered (LPSO) phase, and MgxGd compounds. The grain size is apparently refined and the volume fraction of the eutectic phase increases with increasing Gd. The grain size is not reduced and the divorced eutectic phase is formed with Ca addition. Gd plays a more positive role in the improvement of yield strength while Ca shows a higher enhancement on microhardness. The higher Gd addition results in worse corrosion resistance of the Mg–xGd–1Zn alloy, nevertheless, the alloy with 0.6 wt%Ca has the best corrosion resistance among the Mg–9Gd–1Zn–yCa alloys. The as-cast Mg–3Gd–1Zn alloy exhibits the lowest corrosion rate, and is a promising alloy for biodegradable applications.