Mg-Ca Binary Alloy Research Articles

Selection of Electrolyte Additives for Enhanced Mg-Air Battery Performance Supported By Data-Driven Approach

A Mg-air battery is a primary aqueous battery with high theoretical voltage and specific energy density. They have attracted much attention due to their high theoretical energy density, long shelf life, and safety. They consist of magnesium anode coupled to an air electrode. However, the performance of aqueous Mg-air batteries is relatively poor due to: a large overvoltage caused by formation of insoluble discharge products (MgO and Mg(OH)2); and fast self-corrosion of Mg anodes in aqueous electrolytes. Two main strategies have been developed to address these shortcomings – alloy development [1, 2] and electrolyte modification [3, 4]. Electrolyte additives are an effective way to control interfacial processes. They are inexpensive and straightforward methods for controlling self-corrosion of Mg. As was previously shown electrolyte additives can also improve the discharge performance of aqueous primary Mg-air batteries by changing the surface of Mg anode.Here, we investigated the mechanism of action of several Mg2+ complexing agents as electrolyte additives for aqueous Mg-air batteries [5, 6]. Electrochemical impedance spectroscopy (EIS) measurements during discharge and real-time hydrogen evolution measurements were used to elucidate the mechanisms of action. We found that Mg2+ complexing agents at optimal concentration greatly slowed the formation of insoluble discharge products and decreased the voltage drop in Mg-air batteries. Additionally, anodic hydrogen evolution experiments quantified the effect of Mg2+ complexing agents on self-corrosion of the Mg anode during discharge. These results suggest that Mg2+ complexing agents increase the battery utilization efficiency by inhibiting self-corrosion and decreasing the non-uniform dissolution of the Mg anode. This work showcases the promise of computer-assisted methods for rapidly and efficiently screen large numbers of organic compounds as potential electrolyte additives. Two data-driven quantitative structure-property relationship (QSPR) machine learning models were trained and used for in silico searches for promising battery performance-boosting candidates [7].[1] M. Deng, D. Höche, S.V. Lamaka, D. Snihirova, M.L. Zheludkevich, Mg-Ca binary alloys as anodes for primary Mg-air batteries, J. Power Sources, 396 (2018) 109-118.[2] M. Deng, L. Wang, D. Höche, S.V. Lamaka, P. Jiang, D. Snihirova, N. Scharnagl, M.L. Zheludkevich, Ca/In micro alloying as a novel strategy to simultaneously enhance power and energy density of primary Mg-air batteries from anode aspect, Journal of Power Sources, 472 (2020) 228528.[3] D. Höche, S.V. Lamaka, B. Vaghefinazari, T. Braun, R.P. Petrauskas, M. Fichtner, M.L. Zheludkevich, Performance boost for primary magnesium cells using iron complexing agents as electrolyte additives, Scientific Reports, 8 (2018) 7578.[4] B. Vaghefinazari, D. Höche, S.V. Lamaka, D. Snihirova, M.L. Zheludkevich, Tailoring the Mg-air primary battery performance using strong complexing agents as electrolyte additives, J. Power Sources, 453 (2020) 227880.[5] D. Snihirova, L. Wang, S.V. Lamaka, C. Wang, M. Deng, B. Vaghefinazari, D. Höche, M.L. Zheludkevich, Synergistic Mixture of Electrolyte Additives: A Route to a High-Efficiency Mg-Air Battery, Journal of Physical Chemistry Letters, (2020) 8790-8798.[6] L. Wang, D. Snihirova, M. Deng, B. Vaghefinazari, D. Höche, S.V. Lamaka, M.L. Zheludkevich, Enhancement of discharge performance for aqueous Mg-air batteries in 2,6-dihydroxybenzoate-containing electrolyte, Chem. Eng. J., (2021) 132369.[7] T. Würger, L. Wang, D. Snihirova, M. Deng, S.V. Lamaka, D.A. Winkler, D. Höche, M.L. Zheludkevich, R.H. Meißner, C. Feiler, Data-driven selection of electrolyte additives for aqueous magnesium batteries, Journal of Materials Chemistry A, 10 (2022) 21672-21682.

HRTEM Characterization of an Age-Hardened Mg-Ca Binary Alloy

HRTEM Characterization of an Age-Hardened Mg-Ca Binary Alloy

Elucidating the role of micro-galvanic coupling between eutectic α-Mg lamellas and α-Mg matrix on the hydrogen evolution behaviour of Mg-0.6Ca binary alloy using real-time imaging

ABSTRACT The hydrogen evolution process in the as-cast Mg-0.6Ca alloy was investigated using real-time optical imaging of the corroding surface. It was revealed that hydrogen evolved as large stable bubbles and continuous streams of tiny bubbles because of high localised current density. To the best of the author’s knowledge, this is the first attempt to characterise the hydrogen evolution behaviour of Mg-Ca binary alloy employing a mechanistic model based on real-time imaging.

Effect of Ultrasonic Degassing on Mg-Ca Binary Alloy by Ultrasonic Treatment

The effect of ultrasonic treatment parameters, including ultrasonic treatment duration, frequency resonance, and treatment temperature, on the degassing of Mg-3.03Ca alloys was investigated. The results indicated that the optimum degassing efficiency could be obtained under the ultrasonic resonant condition. When applying ultrasonic treatment for 90 s with 150 W at 700 °C, the minimum hydrogen content and the highest degassing efficiency are obtained, respectively (42.8 cm3/100 g and 27.5%). The ultrasonic treatment can remove the gas from the melt and refine the microstructures. Finally, the mechanism of ultrasonic degassing and refinement was analyzed.

Local galvanic corrosion analysis on cast Mg-Ca binary alloy using scanning Kelvin probe force microscopy

Mg2Ca precipitate effect on the local galvanic corrosion behavior of Mg-Ca alloy was quantitatively evaluated using the surface potential difference between Mg2Ca and α-Mg matrix measured by scanning Kelvin probe force microscopy. In a saltwater immersion test, discontinuous Mg2Ca precipitates acted as anodes and remarkably eroded rather than the matrix.

Does acid pickling of Mg-Ca alloy enhance biomineralization?

The mechanical and physical properties of biodegradable magnesium (Mg) alloys make them suitable for temporary orthopaedic implants. The success of these alloys depends on their performance in the physiological environment. In the present work, surface modification of Mg-Ca binary alloy by acid pickling for better biomineralization and controlled biodegradation is explored. The corrosion rates of nitric and phosphoric acid treated samples were analysed by conducting electrochemical corrosion tests. In vitro degradation behaviour was studied using immersion test in simulated body fluid (SBF). The sample surfaces were characterized using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It is seen that acid pickling leads to significant improvement in biomineralization and develop in situ calcium phosphate (CaP) coating on the sample surfaces. In addition, the treated samples recorded a reduced degradation rate in the SBF compared to untreated samples. Thus, acid pickling is suggested as an effective surface treatment method to tailor the biomineralization and degradation behaviour of the Mg-Ca alloy in the physiological environment.

Effect of extrusion speed on microstructure and mechanical properties of the Mg-Ca binary alloy

Abstract This work reported the effect of extrusion speeds on the microstructures and mechanical properties of Mg-Ca binary alloy. The results showed that yield strength of the as-extruded Mg-1.2 wt.% Ca alloys decrease from ∼ 360 MPa to ∼ 258 MPa as the ram speed increases from 0.4 mm/s to 2.4 mm/s, and the elongation increases from ∼ 3.9% to ∼ 12.2%. The microstructure changes from bimodal grain feature to the complete dynamical recrystallization (DRX) with increase of the extrusion speed. The ultrafine DRXed grains in size of ∼0.85 µm, the numerous nano-Mg2Ca particles dispersing along the grain boundaries and interiors, as well as the high density of residual dislocations, should account for the high strength. It is believed that the high degree of dynamic recrystallization and the resulting texture randomization play the critical roles in the ductility enhancement of the high-speed extruded Mg alloys.

XPS and Electron Microscopy Study of Oxide-Scale Evolution on Ignition Resistant Mg-3Ca Alloy at Low and High Heating Rates

AbstractEarlier work by the authors suggested that the formation of molten eutectic regions in Mg-Ca binary alloys caused a discrepancy in ignition temperature when different heating rates are used. This effect was observed for alloys where Ca content is greater than 1 wt%. In this work, the effect of two heating rates (25 °C/min and 45 °C/min) on the ignition resistance of Mg-3Ca is evaluated in terms of oxide growth using X-ray Photoelectron Spectroscopy. It is found that the molten eutectic regions develop a thin oxide scale of ~100 nm rich in Ca at either heating rate. The results prove that under the high heating rate, solid intermetallics are oxidized forming CaO nodules at the metal/oxide interface that eventually contribute to the formation of a thick and non-protective oxide scale in the liquid state.

Mg-Ca binary alloys as anodes for primary Mg-air batteries

In this research, Mg-Ca binary alloys are evaluated as anode material candidates for primary Mg-air batteries. The effect of Ca content on self-corrosion and discharge performance of Mg anode is investigated through microstructure characterization, electrochemical measurements and half-cell discharge tests. Then the composition of Mg-Ca alloys is optimized in terms of reduced self-corrosion and improved discharge performance. The basic characteristics of Mg-air batteries with optimized Mg-Ca alloy as anode are tested and compared to those based on high purity Mg and defined commercial Mg alloys. The results show that Mg-0.1 wt. % Ca alloy has the best self-corrosion behavior and discharge performance among all prepared Mg-Ca alloys. The Mg-air battery with Mg-0.1 wt. % Ca alloy as anode offers higher cell voltage and specific energy than those based on high purity Mg, AM50 and AZ31 alloys.

Hot Tearing Susceptibility of Mg-Ca Binary Alloys

Hot tearing is known as one of the most critical solidification defects commonly encountered during casting practice. As most Mg alloys are initially prepared by casting, ingots must have superior quality with no casting defects for the further processing. Due to the extensive potential biodegradable applications of binary Mg-Ca alloys, it is of great importance to investigate their hot tearing behavior. In the present study, the influence of Ca content (0.1, 0.2, 0.5, 1.0, and 2.0 wt pct) on hot tearing susceptibility (HTS) of Mg-Ca binary alloys was investigated using a constrained rod casting apparatus equipped with a load cell and data acquisition system. Tear volumes were quantified with 3D X-ray tomography. Results showed that the influence of Ca content on HTS followed a “Λ” shape: the HTS increased with increase in Ca content, reached a maximum at 0.5 to 1 wt pct Ca, and then decreased with further increasing the Ca content to 2.0 wt pct. The wide solidification range and reasonably high volume of intermetallic in the Mg-0.5 wt pct Ca and Mg-1 wt pct Ca alloys resulted in high HTS. Microstructure analysis suggested that the hot tear initiated at grain boundaries and propagated along them through thin film rupture or across the eutectic.

Mg-Ca binary alloy sheets with Ca contents of ≤1 wt.% with high corrosion resistance and high toughness

Mg-Ca alloy sheets with high toughness and corrosion resistance were developed by tailoring the microstructures of Mg-Ca alloys with Ca contents of ≤1% by means of high-ratio differential speed rolling (HRDSR) followed by annealing treatment. Refinement of Mg2Ca phase to submicron sized particles by HRDSR allowed to achieve a fine-grained recrystallised microstructure with low dislocation density after post-HRDSR annealing. The Mg-0.4Ca and Mg-1Ca alloys had the higher toughness and corrosion resistance compared to the pure Mg. The Mg-0.4Ca alloy exhibited a lower strength than the Mg-1%Ca alloy, but it had a higher ductility and a higher corrosion resistance.

Effect of Calcium Content on the Microstructure and Degradation of Mg-Ca Binary Alloys Potentially Used as Orthopedic Biomaterials

The effect of calcium addition in modifying the microstructural aspects and corrosion behavior was investigated on two different biodegradable magnesium alloys type Mg-xCa binary alloys (x = 0.8, 1.8 wt. (%)). Systematic microstructure investigations was made using optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray. Following these experimental investigations, in the microstructure of the investigated Mg-Ca alloys a notable refinement was observed occurred with increasing the calcium content. The evaluation of corrosion resistance was performed both using electrochemical measurements and hydrogen release in simulated body fluid (SBF), as proposed by Kokubo and his colleagues, maintaining the temperature at 37°C. The results showed a lower corrosion resistance when the calcium content was increased, due to the increased Mg2Ca intermetallic phase in grain boundaries. Consequently, our preliminary results showed that MgCa0.8 alloy having a minimal amount of Mg2Ca appear to be a promising alloy to be used as a biomaterial for orthopedic implants.

Effect of the Content of Ca on the Microstructure of Magnesium Alloys

Magnesium-calcium binary alloys were prepared with pure Mg and pure Ca to study the influence of Ca on the microstructure of Mg-Ca binary alloys. The results showed that with the increase of the content of Ca, there is a sharp decrease of the grain size of Mg alloy with Ca content in the range of 0 to 0.5%, then there is slight decrease of grain size with increasing the content of Ca from 0.5 to 2%; the grain size becomes increasing with further increasing the content of Ca.

319 結晶粒微細化によるMg-Ca二元合金の高強度化(OS-4 マグネシウム合金の変形とメカニクス(5))

319 結晶粒微細化によるMg-Ca二元合金の高強度化(OS-4 マグネシウム合金の変形とメカニクス(5))

Characteristics of As-Cast and Forged Biodegradable Mg-Ca Binary Alloy Immersed in Kokubo Simulated Body Fluid

Biodegradable implant is an alternative to metallic implant and has the advantage of not being necessary to remove once the fracture has healed. Magnesium is particularly desirable since it is biocompatible and has a modulus of elasticity closer to bone. In addition, it shows ability to biodegrade in situ, when used as an implant material. In this research, different percentages of calcium were added to magnesium during melting of the alloy. A selected alloy was forged at different parameters. Both as cast and forged alloys were subjected to polarization test performed in Kokubo simulated body fluid. Immersion test in the fluid was conducted for 96 hours to investigate the formation, growth and morphology of the hydroxyapatite on the surface of the alloys. The results showed that similar electrochemical behaviour took place in the alloys regardless of the calcium content. However, an increase in corrosion rate was observed with increasing calcium content. It was also observed that forging process decreased the corrosion resistance of the alloy. Furthermore, increasing calcium content accelerated the growth of bone-like apatite in the alloy.

Microalloying Effect on the Precipitation Processes of Mg-Ca Alloys

The Mg-Ca binary alloys in the Mg-Mg2Ca two-phase region show little precipitation hardening by aging. However, the Mg-Ca alloys microalloyed with Al and Zn result in notable age hardening because of the formation of metastable, internally ordered, plate-like Guinier–Preston (GP) zones on the basal plane. To enhance the age-hardening response, we explored microalloying elements that can alter the habit plane from basal to prismatic. We found that an indium addition causes the homogeneous precipitation of thin plates on prismatic planes, resulting in a pronounced age-hardening response. Based on transmission electron microscopy and atom probe analysis results, we discuss the structure of the GP zones and the possible origin of the habit plane alternation.

Characteristics of As-Cast and Forged Biodegradable Mg-Ca Binary Alloy Immersed in Kokubo Simulated Body Fluid

Biodegradable implant is an alternative to metallic implant and has the advantage of not being necessary to remove once the fracture has healed. Magnesium is particularly desirable since it is biocompatible and has a modulus of elasticity closer to bone. In addition, it shows ability to biodegrade in situ, when used as an implant material. In this research, different percentages of calcium were added to magnesium during melting of the alloy. A selected alloy was forged at different parameters. Both as cast and forged alloys were subjected to polarization test performed in Kokubo simulated body fluid. Immersion test in the fluid was conducted for 96 hours to investigate the formation, growth and morphology of the hydroxyapatite on the surface of the alloys. The results showed that similar electrochemical behaviour took place in the alloys regardless of the calcium content. However, an increase in corrosion rate was observed with increasing calcium content. It was also observed that forging process decreased the corrosion resistance of the alloy. Furthermore, increasing calcium content accelerated the growth of bone-like apatite in the alloy.

Effect of Ultrasonic Treatment on Microstructures of Mg-Ca Binary Alloy

The effects of high intensity ultrasonic melt treatment on the microstructure of magnesium alloys were investigated in this paper. Magnesium melts were treated with power ultrasonic wave and then cooled to a predetermined temperature. With the increase in ultrasonic power, the structure exhibited refined and spheroidzed crystal grains. After further increasing the ultrasonic power, the grains tended to somewhat coarsened. Increasing the ultrasonic processing time led to a grain refinement of magnesium alloy.

Study on Corrosion and Degradation Behavior of Mg-Ca Alloy in Simulated Body Fluid

The corrosion and degradation behavior of Mg-Ca binary alloy in simulated body fluid (SBF) were studied by immersion of pure Mg and Mg-Ca alloys with different Ca contents in SBF. The corrosion process was carried out by real-time measurement of sample weight, pH value of SBF and the microstructures of the immersed samples at different immersion time observed by electron microscopy. The result shows that Mg-Ca alloy with 0.7% Ca has better corrosion resistance than the one with 2.0% Ca. The product generated on the surface of Mg-0.7Ca during the immersion was identified by X-ray diffraction and energy spectrum analysis.