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Due to the high activation energy required for the decomposition of Mg metal hydrides, it can be decomposed into magnesium and H2 when the external temperature reaches 350 °C. In this paper, Nd5Mg41Ni + x wt.% GO (x = 0–4) composites were obtained by planetary ball milling the alloy with GO for 10 h. The alloy has Nd5Mg41, NdMg3, NdMg12 and Mg2Ni phase, and the main phase is Nd5Mg41 phase. The time required for the alloy phase structure composite material to reach the maximum hydrogen desorption capacity of 95 % is 20, 23, 18, 17 and 18 min, and the calculated hydrogen desorption activation energy Ea values are 99.9, 98.1, 95.6, 89.9 and 95.7 kJ/mol H2, the ΔHde of the composites are 77.57, 76.40, 73.48, 70.77 and 81.2 kJ/mol H2, respectively. The alloy particles are embedded in the layered GO to form a special microstructure of the nanocrystalline GO embedded nanocrystalline alloy, which makes the composite material easier to adsorb hydrogen molecules and promotes the dissociation of hydrogen molecules and the diffusion of hydrogen atoms. However, the excessive addition of GO leads to excessive GO coating alloy particles, which hinders the diffusion of hydrogen atoms. The agglomeration of alloy particles leads to the increase of hydrogen desorption enthalpy of the alloy.

Mg80Ni16−xAlxY4 (x = 2, 4, 8) alloys were prepared by induction levitation melting, and the effect of substitution of Al for Ni on the microstructure and hydrogen storage properties was studied in the present work. The results illustrated that the solidification path, phase constitution, and grain size were significantly altered by Al addition. Appropriate Al addition improved abundance and grain refinement of the Mg, Mg2Ni, and Mg15NiY ternary eutectic. But as Al further increased, Mg solidified independently rather than in the formation of the ternary eutectic. More Al favored the formation of Al3Ni2Y but suppressed Mg2Ni and YMgNi4. Although the hydrogen absorption activation and the kinetic property deteriorated, the thermodynamic stability of hydrides was enhanced by adding Al. Hydrogen absorption ability under low pressure was improved, and the Mg80Ni8Al8Y4 alloy could absorb nearly 3.5 wt% hydrogen under 1 bar hydrogen at 250 °C. [ABSTRACT FROM AUTHOR]

Mg77+xNi20−xLa3 (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg2Ni, lamella eutectic composites of Mg + Mg2Ni, and some amount of LaMg12 and La2Mg17. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg77Ni20La3 alloy and Mg82Ni15La3 alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg77Ni20La3, Mg82Ni15La3, Mg87Ni10La3 and Mg92Ni5La3 alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH2. [ABSTRACT FROM AUTHOR]

Mg80Ni16−xAlxY4 (x = 2, 4, 8) alloys were prepared by induction levitation melting, and the effect of substitution of Al for Ni on the microstructure and hydrogen storage properties was studied in the present work. The results illustrated that the solidification path, phase constitution, and grain size were significantly altered by Al addition. Appropriate Al addition improved abundance and grain refinement of the Mg, Mg2Ni, and Mg15NiY ternary eutectic. But as Al further increased, Mg solidified independently rather than in the formation of the ternary eutectic. More Al favored the formation of Al3Ni2Y but suppressed Mg2Ni and YMgNi4. Although the hydrogen absorption activation and the kinetic property deteriorated, the thermodynamic stability of hydrides was enhanced by adding Al. Hydrogen absorption ability under low pressure was improved, and the Mg80Ni8Al8Y4 alloy could absorb nearly 3.5 wt% hydrogen under 1 bar hydrogen at 250 °C.

Magnesium-based materials offer a promising, cost-effective, and high-capacity solution for hydrogen storage. However, their slow kinetics and elevated absorption/desorption temperatures limit their large-scale application. In this study, a series of Mg 1- x /V x (x = 0.05, 0.10, 0.15, 0.20) multilayer films were designed and fabricated using an ultra-high vacuum magnetron sputtering technique. Transmission electron microscopy (TEM) analysis revealed the presence of a discontinuous nanoscale V single-phase interlayer between the Mg layers, confirming the successful formation of Mg/V multilayer films. The surface of the deposited films predominantly consists of hexagonal particles of varying sizes stacked upon one another. Upon hydrogenation, tetragonal rutile structures of MgH 2 and V 2 H were formed. The Mg 0.95 V 0.05 film absorbed 6.40 wt% hydrogen within 15 min at 150 °C and desorbed 0.34 wt% hydrogen within 1.8 h at the same temperature, with an initial dehydrogenation temperature of 79 °C. The activation energies for hydrogen absorption and desorption were estimated to be 60 ± 7 and 140 ± 10 kJ/mol H 2 , respectively, significantly lower than the corresponding values of 100 and 160 kJ/mol H 2 for conventional pure Mg/MgH 2. The enhanced hydrogen absorption performance was attributed to the catalytic effect of nanocrystalline V at the Mg/V incoherent interface, while the improved desorption performance was due to the synergistic catalytic effect of nanocrystalline V 2 H at the MgH 2 /V 2 H incoherent interface. DFT calculations indicated that the interaction at the Mg/V incoherent interface promoted H atom adsorption and diffusion, significantly enhancing the hydrogenation and dehydrogenation performance of the multilayer films. [Display omitted] • Mg/V multilayer films were designed and prepared using magnetron sputtering. • Structure and hydrogen storage properties of Mg/V multilayer films were studied. • DFT calculations revealed that the Mg/V interface strongly adsorbs H atoms. • V and its hydride-induced catalytic effect improve hydrogen absorption/desorption. [ABSTRACT FROM AUTHOR]

Magnesium-based alloys are widely used in the construction of automotive, aviation, and medical applications. The solutions presently used for the production of biodegradable materials are characterized by considerable energy consumption and limitations resulting from the use of different devices and technologies. The proposed material is easier to manufacture due to mechanical alloying (MA). Thanks to the MA process, it is possible to carefully tailor the desired chemical composition and microstructure. There are many parameters that can be modified during synthesis in order to obtain an alloy with the desired microstructure and specific expected alloy properties. The duration of grinding of the alloy, the size and number of balls, and the protective atmosphere have a great influence on the process of mechanical alloying and the properties of the obtained products. So, the aim of this work was to determine the influence of milling time on the phase composition and structure of Mg-based alloy synthesis products. The tested samples were milled for 5, 8, 13, 20, 30, 50, and 70 h. X-ray diffraction analysis (XRD) and scanning electron microscopy studies (SEM) with energy-dispersive spectroscopy (EDS) were performed to obtain the powder morphology and chemical composition of Mg66−xZn30Ca4Agx (where x = 1, 2) powders. Structure characterization based on the Rietveld refinement and crystallite size determination based on the Williamson–Hall theory of milling products were also carried out. [ABSTRACT FROM AUTHOR]

In this investigation, mechanical grinding was applied to fabricating the Mg-based alloys La7Sm3Mg80Ni10 + 5 wt.% M (M = None, TiO2, La2O3) (named La7Sm3Mg80Ni10–5 M (M = None, TiO2, La2O3)). The result reveals that the structures of as-milled alloys consist of amorphous and nanocrystalline. The particle sizes of the added M (M = TiO2, La2O3) alloys obviously diminish in comparison with the M = None specimen, suggesting that the catalysts TiO2 and La2O3 can enhance the grinding efficiency. What's more, the additives TiO2 and La2O3 observably improve the activation performance and reaction kinetics of the composite. The time required by releasing 3 wt.% hydrogen at 553, 573 and 593 K is 988, 553 and 419 s for the M= None sample, and 578, 352 and 286 s for the M = TiO2 composite, and 594, 366, 301 s for the La2O3 containing alloy, respectively. The absolute value of hydrogenation enthalpy change |ΔH| of the M (M = None, TiO2, La2O3) alloys is 77.13, 74.28 and 75.28 kJ/mol. Furthermore, the addition of catalysts reduces the hydrogen desorption activation energy (Eade).

The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction. The catalysis of Co@C composites on the hydrogen storage behavior of Mg90Ce5Y5 alloy was investigated in detail by XRD, SEM, TEM, PCI, and DSC method. Because of the synergistic catalytic function of C and Co in C@Co nanocomposites, the Mg90Ce5Y5 alloy with 10 wt.% C@Co shows the excellent hydrogen absorption and desorption performances. Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300 °C. Meanwhile, the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol−1 H2 after the addition of the C@Co composites. This positive effect attributes to the C layer with the high defect density and the Co nanoparticles, which reduces the energy barriers for the nucleation of Mg/MgH2 phase and the recombination of hydrogen molecule. Besides, the C@Co composites also improve the activation property of the Mg90Ce5Y5 alloy which was fully activated in the first cycle. Moreover, the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased. Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy, these differences are so small that the improvement on thermodynamics can hardly be seen.

Mg77+xNi20−xLa3 (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg2Ni, lamella eutectic composites of Mg + Mg2Ni, and some amount of LaMg12 and La2Mg17. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg77Ni20La3 alloy and Mg82Ni15La3 alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg77Ni20La3, Mg82Ni15La3, Mg87Ni10La3 and Mg92Ni5La3 alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH2.

Background: Since Lambotte and Payr first studied Mg-based alloys for orthopedics in 1900, the research of this field has finally ushered in vigorous development in the 21st century. From the perspective of quantitative analysis, this paper clearly demonstrated the global research trend from 2005 to 2021 by using bibliometrics and scientometric analysis.Methods: We obtained the publications from the Web of Science Core Collection (WoSCC) database. The bibliometric and scientometric analysis was conducted by using R software, CiteSpace software, VOSviewer software, Pajek software and Microsoft Excel program.Results: In total, 1921 publications were retrieved. It can be found that the number of publications is gradually increasing year by year. We can find that the most prolific countrie, institution and researcher are China, Chinese Academy of Sciences and Zheng Yufeng, respectively. The most influential journals in this field are Acta Biomaterialia and Biomaterials, with 16,511 and 12,314 total citations, respectively. By conducting the co-cited documents-based clustering analysis, 16 research hotspots and their representative studies have been identified. Besides, by conducting analysis of keywords, we divided the keyword citation bursts representing the development of the field into three stages.Conclusion: The number of researches on the biodegradable Mg-based alloys increased sharply all over the world in the 21st century. China has made significant progress in biodegradable Mg-based alloy research. More focus will be placed on osteogenic differentiation, fabrication, graphene oxide, antibacterial property, bioactive glass and nanocomposite, which may be the next popular topics in the field.

This study focused on the design and the preparation method of a new biomaterial, Mg30Zn30Sn30Sr5Bi5 (at%) alloy, and its simulation and property analyses. Based on the comprehensive consideration of the preparation of high-entropy alloys, the selection of biomaterial elements, and the existing research results of common Mg-based materials, the atomic percentage of various elements, that is, Mg:Zn:Sn:Sr:Bi = 30:30:30:5:5, was determined. Using the theoretical methods of thermodynamic performance analysis and solidification performance analysis, the proposed composition was simulated and analyzed. The analysis results showed that the mechanical properties of the new material can meet the design requirements, and it can be prepared in physical form. XRD, SEM, PSD, compression tests, and other experimental tests were conducted on the material, and the alloy composition and distribution law showed various characteristics, which conformed to the "chaotic" characteristics of high-entropy alloys. The elastic modulus of the material was 17.98 GPa, which is within the 0–20 GPa elastic modulus range of human bone. This means that it can avoid the occurrence of stress shielding problems more effectively during the material implantation process. [ABSTRACT FROM AUTHOR]

Alloys based on magnesium are of considerable scientific interest as they have very attractive mechanical and biological properties that could be used to manufacture biodegradable materials for medical applications. Mechanical alloying is a very suitable process to obtain alloys that are normally hard to produce as it allows for solid-state diffusion via highly energetic milling, producing fine powders. Powders obtained by this method can be sintered into nearly net-shape products, moreover, their phase and chemical composition can be specifically tailored. This work aims to investigate the effect of milling time on the density, microstructure, phase composition, and mechanical properties of Mg-Zn-Ca-Pr powders processed by high energy mechanical alloying (HEMA) and consolidated by spark plasma sintering (SPS). Thus, the results of XRD phase analysis, particle size distribution (granulometry), density, mechanical properties, SEM investigation of mechanically alloyed and sintered Mg-Zn-Ca-Pr alloy are presented in this manuscript. The obtained results illustrate how mechanical alloying can be used to produce amorphous and crystalline materials, which can be sintered and demonstrates how the milling time impacts their microstructure, phase composition, and resulting mechanical properties. [ABSTRACT FROM AUTHOR]

In this investigation, mechanical grinding was applied to fabricating the Mg-based alloys La 7 Sm 3 Mg 80 Ni 10 + 5 wt.% M (M = None, TiO 2 , La 2 O 3) (named La 7 Sm 3 Mg 80 Ni 10 –5 M (M = None, TiO 2 , La 2 O 3)). The result reveals that the structures of as-milled alloys consist of amorphous and nanocrystalline. The particle sizes of the added M (M = TiO 2 , La 2 O 3) alloys obviously diminish in comparison with the M = None specimen, suggesting that the catalysts TiO 2 and La 2 O 3 can enhance the grinding efficiency. What's more, the additives TiO 2 and La 2 O 3 observably improve the activation performance and reaction kinetics of the composite. The time required by releasing 3 wt.% hydrogen at 553, 573 and 593 K is 988, 553 and 419 s for the M = None sample, and 578, 352 and 286 s for the M = TiO 2 composite, and 594, 366, 301 s for the La 2 O 3 containing alloy, respectively. The absolute value of hydrogenation enthalpy change |Δ H | of the M (M = None, TiO 2 , La 2 O 3) alloys is 77.13, 74.28 and 75.28 kJ/mol. Furthermore, the addition of catalysts reduces the hydrogen desorption activation energy (E a de). [ABSTRACT FROM AUTHOR]

The composites comprised of Co nanoparticle and C nanosheet were prepared though a high-temperature carbonization reaction. The catalysis of Co@C composites on the hydrogen storage behavior of Mg 90 Ce 5 Y 5 alloy was investigated in detail by XRD, SEM, TEM, PCI, and DSC method. Because of the synergistic catalytic function of C and Co in C@Co nanocomposites, the Mg 90 Ce 5 Y 5 alloy with 10 wt.% C@Co shows the excellent hydrogen absorption and desorption performances. Time for releasing hydrogen reduces from 150 min to 11 min with the addition of the C@Co composites at the temperature of 300 °C. Meanwhile, the dehydrogenation activation energy also declines from 130.3 to 81.9 kJ mol−1 H 2 after the addition of the C@Co composites. This positive effect attributes to the C layer with the high defect density and the Co nanoparticles, which reduces the energy barriers for the nucleation of Mg/MgH 2 phase and the recombination of hydrogen molecule. Besides, the C@Co composites also improve the activation property of the Mg 90 Ce 5 Y 5 alloy which was fully activated in the first cycle. Moreover, the temperature for initial dehydrogenation and the endothermic peak of the alloy hydride were also decreased. Although the addition of the C@Co composites increases the plateau pressures and decreases the value of the decomposition enthalpy, these differences are so small that the improvement on thermodynamics can hardly be seen. [ABSTRACT FROM AUTHOR]

Magnesium-based alloys are widely used in the construction of automotive, aviation, and medical applications. The solutions presently used for the production of biodegradable materials are characterized by considerable energy consumption and limitations resulting from the use of different devices and technologies. The proposed material is easier to manufacture due to mechanical alloying (MA). Thanks to the MA process, it is possible to carefully tailor the desired chemical composition and microstructure. There are many parameters that can be modified during synthesis in order to obtain an alloy with the desired microstructure and specific expected alloy properties. The duration of grinding of the alloy, the size and number of balls, and the protective atmosphere have a great influence on the process of mechanical alloying and the properties of the obtained products. So, the aim of this work was to determine the influence of milling time on the phase composition and structure of Mg-based alloy synthesis products. The tested samples were milled for 5, 8, 13, 20, 30, 50, and 70 h. X-ray diffraction analysis (XRD) and scanning electron microscopy studies (SEM) with energy-dispersive spectroscopy (EDS) were performed to obtain the powder morphology and chemical composition of Mg66−xZn30Ca4Agx (where x = 1, 2) powders. Structure characterization based on the Rietveld refinement and crystallite size determination based on the Williamson–Hall theory of milling products were also carried out.

Alloys based on magnesium are of considerable scientific interest as they have very attractive mechanical and biological properties that could be used to manufacture biodegradable materials for medical applications. Mechanical alloying is a very suitable process to obtain alloys that are normally hard to produce as it allows for solid-state diffusion via highly energetic milling, producing fine powders. Powders obtained by this method can be sintered into nearly net-shape products, moreover, their phase and chemical composition can be specifically tailored. This work aims to investigate the effect of milling time on the density, microstructure, phase composition, and mechanical properties of Mg-Zn-Ca-Pr powders processed by high energy mechanical alloying (HEMA) and consolidated by spark plasma sintering (SPS). Thus, the results of XRD phase analysis, particle size distribution (granulometry), density, mechanical properties, SEM investigation of mechanically alloyed and sintered Mg-Zn-Ca-Pr alloy are presented in this manuscript. The obtained results illustrate how mechanical alloying can be used to produce amorphous and crystalline materials, which can be sintered and demonstrates how the milling time impacts their microstructure, phase composition, and resulting mechanical properties.

Biodegradable magnesium alloys are promising candidates for use in biomedical applications. However, degradable particles (DPs) derived from Mg-based alloys have been observed in tissue in proximity to sites of implantation, which might result in unexpected effects. Although previous in vitro studies have found that macrophages can take up DPs, little is known about the potential phagocytic pathway and the mechanism that processes DPs in cells. Additionally, it is necessary to estimate the potential bioeffects of DPs on macrophages. Thus, in this study, DPs were generated from a Mg-2.1Nd-0.2Zn-0.5Zr alloy (JDBM) by an electrochemical method, and then macrophages were incubated with the DPs to reveal the potential impact. The results showed that the cell viability of macrophages decreased in a concentration-dependent manner in the presence of DPs due to effects of an apoptotic pathway. However, the DPs were phagocytosed into the cytoplasm of macrophages and further degraded in phagolysosomes, which comprised lysosomes and phagosomes, by heterophagy instead of autophagy. Furthermore, several pro-inflammatory cytokines in macrophages were upregulated by DPs through the induction of reactive oxygen species (ROS) production. To the best of our knowledge, this is the first study to show that DPs derived from a Mg-based alloy are consistently degraded in phagolysosomes after phagocytosis by macrophages via heterophagy, which results in an inflammatory response owing to ROS overproduction. Thus, our research has increased the knowledge of the metabolism of biodegradable Mg metal, which will contribute to an understanding of the health effects of biodegradable magnesium metal implants used for tissue repair. Biomedical degradable Mg-based alloys have great promise in applied medicine. Although previous studies have found that macrophages can uptake degradable particles (DPs) in vitro and observed in the sites of implantation in vivoin vivo , few studies have been carried out on the potential bioeffects relationship between DPs and macrophages. In this study, we analyzed the bioeffects of DPs derived from a Mg-based alloy on the macrophages. We illustrated that the DPs were size-dependently engulfed by macrophages via heterophagy and further degraded in the phagolysosome rather than autophagosome. Furthermore, DPs were able to induce a slight inflammatory response in macrophages by inducing ROS production. Thus, our research enhances the knowledge of the interaction between DPs of Mg-based alloy and cells, and offers a new perspective regarding the use of biodegradable alloys. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Mg-based alloys have great potential for application owing to their high hydrogen storage capacity but still suffer from too high temperature to absorb/desorb hydrogen due to overly stable de/hydriding thermodynamics and poor kinetics. To overcome this barrier, in this work, atomic-scale superlattice structures have been successfully fabricated in Mg-Zr modulation films using a self-designed semi-co-sputtering method. For comparison, Mg/Zr multilayer films with thicker layers are also prepared. The Mg/Zr interface density in Mg-Zr modulation films is much higher than in Mg/Zr multilayer films, thus exhibiting different structure changes in hydrogenation and excellent hydrogen storage properties. Transmission electron microscopy observation shows that the as-deposited Mg-Zr modulation films have ultra-thin coherent layers and grow along the [0001] direction. These modulated films keep their original lattice structure after de/hydrogenation, indicating the formation of solid solution with the entering of hydrogen atoms into the film. In contrast, the Mg/Zr multilayer films form MgH 2 phase after hydrogenation. The Mg-Zr modulation film absorbs hydrogen at room temperature and begins to release hydrogen at approximately 81 °C, whereas the hydrogen release temperature of the conventional MgH 2 and the present Mg/Zr multilayer film is about 287 and 171 °C, respectively. DFT calculation further reveals that the great enhancement of the above-mentioned properties can be attributed to the synergetic effect of Zr catalysis and strain induced by coherent heterointerfaces. The present work provides a new insight for developing Mg-based hydrogen storage alloys. This manuscript has not been published or presented elsewhere in part or entirety and is not under consideration by another journal. We have read and understood your journal's policiesand believe that neither the manuscript nor the study violatesthese. There are no conflicts of interest to declare. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to investigate the effect of the rare earth element Y on the strengthening potency of magnesium alloys and its strengthening mechanism under tension. In this paper, the solid solution structures with Y atom content of 1.8 at.% and 3.7 at.% were built, respectively, and their cohesive energies and stress-strain curve were calculated in the strain range of 0–20%. The calculation results of the cohesive energies showed that the structure of element Y is more stable with the increase of strains. The calculation results of stress and strain showed that Y element can improve the yield strength and tensile strength of the Mg-based alloy, and the strengthening effect is better when the Y content is 3.7 at.%.

Abstract Hydrogenation properties of two five-component Mg 60 Ce 10 Ni 20 Cu 5 X 5 (X = Co, Zn) metallic glasses have been studied. Using high-pressure differential scanning calorimetery (HP-DSC) under hydrogen atmosphere and hydrogenation kinetics study, it is demonstrated that alloying with Zn shows negligible impact on the hydrogenation kinetics and storage capacity of the Mg Ce Ni Cu metallic glass, however, alloying with Co remarkably improves the hydrogenation kinetics and storage capacities. Apparent activation energies for hydrogenation are calculated to be 64.4 kJ/mol, and 107.2 kJ/mol, for the Mg 60 Ce 10 Ni 20 Cu 5 Co 5 and Mg 60 Ce 10 Ni 20 Cu 5 Zn 5 metallic glasses, respectively. Theoretical calculations are performed to understand the atomic structure of the five-component metallic glasses. It shows that the overall, Mg Mg pair and Mg Ni pair distribution functions (PDFs) of the Mg 60 Ce 10 Ni 20 Cu 5 Co 5 and Mg 60 Ce 10 Ni 20 Cu 5 Zn 5 metallic glasses are almost the same, indicating that geometry issue is not a key factor on influencing the hydrogenation properties of the studied Mg-based metallic glasses. It is proposed that chemical composition is the key to improve the hydrogenation properties of Mg-based metallic glasses. Graphical abstract This study shows a simple method to tune the hydrogenation properties of Mg-based metallic glasses via alloying. A new five-component Mg 60 Ce 10 Ni 20 Cu 5 Co 5 metallic glass with significantly enhanced hydrogenation kinetics and capacity has been reported. Image 1 Highlights • Hydrogenation properties of five-component Mg-based metallic glasses are studied. • Addition of Co greatly improves the hydrogenation kinetics and capacity. • Geometrical and chemical considerations on hydrogenation properties are revealed. [ABSTRACT FROM AUTHOR]

Abstract Biodegradable magnesium alloy was coated by nanostructured monticellite (Mon; CaMgSiO 4) through electrophoretic deposition (EPD) coupled with plasma electrolytic oxidation (PEO) with the purpose of enhancing the corrosion properties, bioactivity, and cytocompatibility. The monticellite layer with a thickness of 15 μm and strong adhesion with the PEO coated Mg alloy is able to provide the corrosion protection for the Mg substrate. Microstructural analysis depicted that the monticellite coatings were homogeneous with no obvious cracks or pinholes on the surface of PEO coated Mg alloy. The electrochemical tests in SBF exhibited that the corrosion rate of the Mg alloy was considerably reduced after preparation of monticellite layer on its surface. Furthermore, high impedance of the monticellite coated Mg alloy was observed even after 96 h of incubation in SBF. The apatite layer with spherical morphology was formed on the monticellite surface via interaction of OH− ions from SBF which could accelerate the healing process. The biocompatibility was evaluated via examination of the osteoblastic MG-63 cells response in-vitro. Deposition of nanostructured monticellite induces high osteoblastic proliferation and supplies suitable sites for cell attachment and growth. The cell adhesion and viability are also determined to evaluate the biological response. Moreover, biphasic drug release graphs of the monticellite coating containing tetracycline show an initial immediate release which is followed by more stable release patterns. Overall, it is anticipated that the novel proposed nanostructured coatings of monticellite can improve the corrosion resistance and cytocompatability of the Mg alloys, which make it useful for orthopedic implants. Graphical abstract Image 1 Highlights • Nanostructured monticellite coating was formed on Mg alloy for first time. • Degradation mechanisms of nanostructured monticellite coating was demonstrated. • Monticellite coating was enhanced bioactivity and cytocompatability of Mg alloy. • Monticellite-tetracycline coating presented desired antimicrobial activity. [ABSTRACT FROM AUTHOR]

Magnesium-based materials are interesting alternatives for medical implants, as they have promising mechanical and biological properties. Thanks to them, it is possible to create biodegradable materials for medical application, which would reduce both costs and time of treatment. Magnesium as the sole material, however, it is not enough to support this function. It is important to determine proper alloying elements and methods. A viable method for creating such alloys is mechanical alloying, which can be used to design the structure and properties for proper roles. Mechanical alloying is highly influenced by the milling time of the alloy, as the time of the process affects many properties of the milled powders. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) were carried out to study the powder morphology and chemical composition of Mg65Zn30Ca4Gd1 powders. Moreover, the powder size was assessed by granulometric method and the Vickers hardness test was used for microhardness testing. The samples were milled for 6 min, 13, 20, 30, 40, and 70 h. The hardness correlated with the particle size of the samples. After 30 h of milling time, the average value of hardness was equal to 168 HV and it was lower after 13 (333 HV), 20 (273 HV), 40 (329 HV), and 70 (314 HV) h. The powder particles average size increased after 13 (31 μm) h of milling time, up to 30 (45–49 μm) hours, and then sharply decreased after 40 (28 μm) and 70 (12 μm) h.

Abstract To illuminate the effects of eutectic structure on the de-/hydrogenation properties of Mg-based alloy, Mg-9Ni, Mg-12Cu and Mg-6Ni-3Cu (at. %) alloys with nearly the same primary Mg proportion are prepared. Mg 2 Ni and Mg 2 Cu respectively form a eutectic structure with Mg and tunable eutectic is obtained via Cu partial substituting Ni. Mg-6Ni-3Cu alloy shows excellent activation performance and rapid absorption rates without any sacrifice of desorption rates, leading to a maximum hydrogen capacity of 6.5 wt% H 2 under 300 °C 3 MPa. Different from the independent de-/hydriding behavior of Mg->12Cu alloy, Mg-6Ni-3Cu alloy shows perfectly wide pressure-composition-isotherm plateau with minimal slope. The dehydrogenation models of experimental hydrides are determined. Owing to Cu substitution, the dehydrogenation activation energy reduces from 95.82 to 67.34 kJ mol−1 H 2 , the onset/peak desorption temperature also reduces significantly. It is the spatial connected eutectic and its increased boundaries that facilitate the activation and H diffusion process, which greatly compensate the negative impacts of reduced hydrogenation driving force caused by Mg 2 Cu. The rapid H diffusion coupled with the increased dehydrogenation driving force collectively facilitates its dehydriding process. Graphical abstract Image 1 Highlights • Mg-6Ni-3Cu alloy shows excellent activation property and 6.5 wt% H 2 absorption capacity. • The activation energy of Mg-6Ni-3Cu hydride for desorption reduces to 67.34 kJ mol−1 H 2. • Spatial connected Mg 2 Ni/Mg 2 Cu eutectic promotes H 2 dissociation and H diffusion. • Cu addition can regulate Mg-Mg 2 Ni eutectic structure and improve de-/hydriding kinetics. [ABSTRACT FROM AUTHOR]

The four Mg-based bulk metallic glass forming alloys Mg 59.5 Cu 22.9 Ag 6.6 Gd 11 , Mg 61 Cu 28 Gd 11 , Mg 54 Cu 28 Ag 7 Y 11 , and Mg 65 Cu 25 Y 10 are investigated to gain insight into their thermodynamic and kinetic properties. Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) in three point beam bending mode are used. The gathered data sets are used to evaluate the origin of the high glass forming ability of these systems, which is found in low thermodynamic driving forces for crystallization and sluggish kinetics. Furthermore, sub-T g effects are observed via dynamic mechanical analysis (DMA) and modulated differential scanning calorimetry (MDSC) of as-cast samples. These are interpreted as related to the α-relaxation time spectrum instead of being caused by a Johari-Goldstein-type relaxation mechanism. [ABSTRACT FROM AUTHOR]

Yttrium (Y) is selected to modify the microstructure of magnesium (Mg) to improve the hydrogen storage performance. Thereby, binary alloys with the nominal compositions of Mg 24 Y x ( x  = 1–5) are fabricated by inexpensive casting technique. Their microstructure and phase transformation during hydriding and dehydriding process are characterized by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analysis. The isothermal hydrogen absorption and desorption kinetics are also measured by a Sievert's-type apparatus at various temperatures. Typical multiphase structures of binary alloy can be clearly observed. All of these alloys can reversibly absorb and desorb large amount of hydrogen at proper temperatures. The addition of Y markedly promotes the hydrogen absorption kinetics. However, it results in a reduction of reversible hydrogen storage capacity. A maximum value of dehydrogenation rate is observed with the increase of Y content. The Mg 24 Y 3 alloy has the optimal desorption kinetic performance, and it can desorb about 5.4 wt% of hydrogen at 380 °C within 12 min. Combining Johnson–Mehl–Avrami kinetic model and Arrhenius equation, the dehydrogenation activation energy of the alloys are evaluated. The Mg 24 Y 3 alloy also has the lowest dehydrogenation activation energy (119 kJ mol −1 ). [ABSTRACT FROM AUTHOR]

Ternary Mg 24 Y 3 –5 wt.% Ni– x wt.% GR ( x = 0–10) composites were prepared by mechanical ball-milling. The phase composition, microstructure and hydrogen storage properties were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Sievert's testing method. Results show that adding an appropriate amount of GR has a beneficial effect on reducing particle size and promoting ball-milling efficiency. Sample with 3 wt.% GR content has a composite structure composed of amorphous and nanocrystalline, as a result, showing an excellent hydrogen absorption kinetics even at 100 °C. Differential scanning calorimetry (DSC) tests were used to evaluate the dehydrogenation performance. The peak temperature was reduced from 325 °C to 295 °C with increasing GR content from 0 to 3 wt.%, which can be attributed to the grain refinement and contact improvement between catalytic Ni and Mg 24 Y 3 alloy particles. However, larger flaky Mg 24 Y 3 alloy particles were observed with a further increase of GR content, which is mainly due to the excessive GR addition reduces ball-milling efficiency. The benefit would be completely lost with the GR adding amount up to 10 wt.%. [ABSTRACT FROM AUTHOR]

In this paper, a continuous and uniform Mg-alloy coating was deposited by magnetron sputtering to protect flexible polyimide substrate from atomic oxygen (AO) erosion in the low earth orbit. AO exposure experiments indicated that the erosion yield of the as-deposited Mg-alloy coating was 8.897 × 10 −26 cm 3 atom −1 , about two orders of magnitude lower than that of blank polyimide. During AO exposure, a relatively compact and continuous thin MgO scale formed on the surface of the Mg-alloy coating, resulting in the enhanced AO erosion resistance of the polyimide with Mg-alloy coating. [ABSTRACT FROM AUTHOR]

Metal hydrides are promising materials for solid-state hydrogen storage, however, their gravimetric hydrogen storage density is generally low. In addition, they may also exhibit poor activity, sluggish de/hydrogenation kinetics and high thermodynamic stability, in particular for metal hydrides with high storage capacity. Because of the long-range disordered atomic structure, the amorphous structure, showing a wider interstitial configuration diversity, can provide hydrogen with more types of occupation sites. Such unique property leads to much larger hydrogen storage capacity, faster de/hydrogenation kinetics, local thermodynamic destabilization and even destruction resistance. Therefore, making use of amorphous structure is one of the attractive strategies for promoting the performance of metal hydrides. To develop amorphous hydrogen storage alloys, composition design is the first issue, and two main factors should be considered. One is the glass forming ability of alloys and the other is hydrogen storage ability of the alloys. Comparing with the crystalline counterparts, the amorphous hydrogen storage alloys exhibit some unique features: (1) the non-Arrhenius hydrogen diffusion; (2) the deviation from the Sieverts' law; (3) protean hydrogen-induced phase separation/crystallization; (4) plateau-free pressure-composition-isothermal curve; (5) excessed storage capacity; etc. Till now, the developed hydrogen storage amorphous alloys are mainly Ti-based, Zr-based and Mg-based alloys. Some amorphous alloys do show attractive performance. In particular, Mg-based amorphous alloys have been investigated extensively in recent years. The hydrogen storage capacity in Mg-based amorphous alloys can be readily higher than 3.0 wt%-H, and with addition of other elements, one can also obtain reasonable de/hydrogenation rate and temperature during electrochemical or gaseous process. Though the de/hydrogenation capacity and kinetics of the amorphous alloys can be much better than the crystalline counterparts, there are still great challenges, such as amorphous structure stability, long-cycle reversible de/hydrogenation and irreversible hydrogen-induced amorphous phase transformation. With further exploration of alloy composition and material processing, there are great chances in using hydrogen storage amorphous alloys as energy storage material. [ABSTRACT FROM AUTHOR]

A valid strategy via a gas-solid reaction for preparing Mg-based nanocomposite with controllable crystallite size and suitable for massive production is proposed. The nanocomposites consisting of well-dispersed catalytic nano-Mg 2 NiH 4 /CeH 2.73 embedded in the nano-MgH 2 matrix with crystallite sizes of all phases below 10 nm are fabricated via controlling activation temperature and hydrogen gas (H 2 ) pressure upon the amorphous Mg 80 Ce 10 Ni 10 alloy. Increasing H 2 pressure and reducing temperature are beneficial for obtaining fine hydrides, leading to lowered hydrogen desorption temperature. MgH 2 and CeH 2.73 gradually grow up with the increase of de-/re-hydrogenation cycles, while Mg 2 NiH 4 remains stable during cycling. After 15 de-/re-hydrogenation cycles, the finest nanocomposite shows remarkably reduced activation energy of dehydrogenation of 87 ± 7 kJ/mol (∼160 kJ/mol for commercial MgH 2 ). [ABSTRACT FROM AUTHOR]

The utilization of Mg alloys for solid-state hydrogen storage has attracted considerable attention, and the Mg-based alloys with long period stacking ordered (LPSO) structure show optimized hydrogen storage properties. In this study, solid-solution treatment and hot-extrusion are utilized to modify the hydrogen storage properties of Mg 96 Y 2 Zn 2 alloy. The results indicate 14H-type LPSO structure is precipitated after solid-solution treatment. Dynamic recrystallization occurs during deformation process with the refined grain size of 2 μm approximately and the dynamic precipitation of Mg 3 Y 2 Zn 3 particles leads to the aggregation of Y and Zn atoms. Hot-extrusion can enhance the pulverization resistance of Mg 96 Y 2 Zn 2 alloy by increasing the lattice parameter ratio of c to a. The reduced hydrogen capacity of hot-extruded Mg 96 Y 2 Zn 2 alloy is attributed to the increased pulverization resistance and decreased lattice parameters. The apparent activation energies for hydrogenation and dehydrogenation of solid-solution treated alloy are 6.86 and 13.65 kJ·mol−1 less than those of hot-extruded alloy, respectively. The dehydrogenation temperature of solid-solution treated alloy hydride is 18 °C lower than that of hot-extruded alloy. More abundant and uniform distribution of Y atoms can generate accordingly more abundant and uniform YH 2 nanoscale particles that embed in the α-Mg matrix, which contributes to faster de/hydrogenation kinetics. [Display omitted] • High proportion of widely dispersed LPSO phase is obtained by 14H precipitation. • Hot-extrusion motivates dynamic precipitation resulting in aggregation of Y and Zn. • Faster kinetics is obtained by more uniformly distributed YH 2 nanophase. [ABSTRACT FROM AUTHOR]

• Ni-MH battery can be assembled with amorphous Mg-Ni anode by using the concentrated TMAH electrolyte. • Concentrated TMAH electrolyte shows an ionic-liquid-like hydrate structure. • Concentrated TMAH electrolyte enables excellent cycle life for Mg-based anodes. • In-situ forming Cu coating can suppress the corrosion of Mg-based anodes and increase rate capability. [Display omitted] Mg-based alloy anodes suffer from severe corrosion in conventional electrolytes (KOH solution) and this substantially obstructs the cycle life, which is a great challenge for using them in the Ni-MH battery. Herein, a high concentration tetramethylammonium hydroxide (TMAH) aqueous electrolyte with a special hydrate structure is explored and enables excellent cycle stability and high capacity for Mg-based alloy anodes. In this electrolyte, the Mg 0.4 Ti 0.1 Ni 0.5 alloy anode delivers a maximum discharge capacity of 466 mAh g−1, and maintains 210 mAh g−1 after 100 cycles owing to the reduced corrosion rate, which are much better than that in 6 M KOH electrolyte, being 425 mAh g−1 and 69 mAh g−1, respectively. Furthermore, by in-situ forming Cu coating on the Mg 0.4 Ti 0.1 Ni 0.5 electrode surface during charging process with the adding 0.01 M of Cu(OH) 2 in TMAH electrolyte, the corrosion of the electrode is further suppressed and the reversible capacity can reach 313 mAh g−1 after 100 cycles. The high conducting Cu coating can also increase the rate capability of the electrode by promoting the charge transfer. Thus, using TMAH electrolytes provides a new approach to promote the electrochemical performances of Ni-MH batteries with Mg-based alloy anodes. [ABSTRACT FROM AUTHOR]

Background: Since Lambotte and Payr first studied Mg-based alloys for orthopedics in 1900, the research of this field has finally ushered in vigorous development in the 21st century. From the perspective of quantitative analysis, this paper clearly demonstrated the global research trend from 2005 to 2021 by using bibliometrics and scientometric analysis. Methods: We obtained the publications from the Web of Science Core Collection (WoSCC) database. The bibliometric and scientometric analysis was conducted by using R software, CiteSpace software, VOSviewer software, Pajek software and Microsoft Excel program. Results: In total, 1921 publications were retrieved. It can be found that the number of publications is gradually increasing year by year. We can find that the most prolific countrie, institution and researcher are China, Chinese Academy of Sciences and Zheng Yufeng, respectively. The most influential journals in this field are Acta Biomaterialia and Biomaterials, with 16,511 and 12,314 total citations, respectively. By conducting the co-cited documents-based clustering analysis, 16 research hotspots and their representative studies have been identified. Besides, by conducting analysis of keywords, we divided the keyword citation bursts representing the development of the field into three stages. Conclusion: The number of researches on the biodegradable Mg-based alloys increased sharply all over the world in the 21st century. China has made significant progress in biodegradable Mg-based alloy research. More focus will be placed on osteogenic differentiation, fabrication, graphene oxide, antibacterial property, bioactive glass and nanocomposite, which may be the next popular topics in the field., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zheng, Xu, Xu and Xue.)

Abstract: Bulk metallic glasses of Mg60Ni23.6Y x La(16.4−x) and Mg65Ni20Y x LaMM(15−x) with 0≤ x ≤1at.% have been produced by injection casting. For the La-containing alloy a maximum amorphous diameter of 4mm for x =0.5 and 0.75 was obtained. The LaMM-containing alloy showed a maximum amorphous diameter of 2mm for x =0 and 0.25 but decreased to 1mm with further Y additions. The glass-forming ability of the Mg60Ni23.6La16.4 alloy decreased when La is partially substituted by small amounts of small atoms (Si or B) or by large atoms (Y and Si). [Copyright &y& Elsevier]

Abstract: Amorphous NiB was prepared by chemical reduction method. The effects of NiB on the electrochemical properties of MgNi alloy were investigated. MgNi–NiB composite was prepared by mechanical alloying (MA). The MgNi–NiB (weight ratio 100:10) composite which was MA 15h exhibited the best performance. After 50 charge–discharge cycles, the specific discharge capacity was still above 210mAhg−1 and the capacity retention was 50.15%, which was much higher than that of MgNi (no more than 10%). The exchange current density I 0 increased with the increasing of NiB (from 67.60 to 344.80mAg−1) which indicated that NiB improved the electrochemical kinetics of the hydrogenation/dehydrogenation of MgNi alloy in alkaline solutions. Potentiodynamic polarization results showed that the corrosion voltage (E corr) got a positive shift from −0.933 to −0.879V and corrosion current density was decrease from 4.69E−4A to 1.24E−5A, which indicated that the larger corrosion resistance of MgNi alloys in an alkaline solution which benefited from the introduction of NiB. The electrochemical impedance spectroscopy results showed that the values of whole ohmic resistance (R s) and charge transfer resistance (R 1) of the MgNi–NiB alloy were reduced by NiB comparing with MgNi. In conclusion, NiB improved the electrochemical characteristics of the MgNi alloy significantly. [Copyright &y& Elsevier]

• Substituting La by Sm or Ce can improve the hydrogen storage property of alloys. • Sm 3 H 7 and CeH 3 formed in the alloy act as catalysts during de-/hydriding process. • Substitution of Sm or Ce for La improves the activation and kinetics of the alloy. Nano-rare earth hydrides generated in situ were believed to catalyze the reversible reaction of magnesium-based alloys and hydrogen. In this paper, La in La 2 Mg 16 Ni 2 was partially substituted by Ce or Sm. The related impacts of element substitution by Sm or Ce on the structure and hydrogen storage properties of the La 10- x RE x Mg 80 Ni 10 (x = 0 or 3; RE = Sm or Ce) alloys were investigated in detail. XRD, SEM and TEM were used to characterize the microstructure of the alloys. The thermodynamics and kinetics of hydrogen storage reaction at specific temperatures were measured by an automatic Sievert apparatus. The non-isothermal dehydrogenation performance of the alloys was investigated by thermogravimetry (TGA) and differential scanning calorimetry (DSC) at different heating rates. It is revealed that the major phase of alloys is La 2 Mg 17 and the secondary phases are Mg 2 Ni and La 2 Ni 3 , respectively. There is no new phase appearing with the addition of Ce or Sm as the elements Ce and Sm exist in the solid solution of the alloy. The addition of Ce or Sm makes the grain of the as-cast alloy obviously refined. The related reaction kinetics is ameliorated obviously by the method of replacing La with Ce or Sm. Moreover, the operation makes the stability of the hydride visibly declined and reduces the initial temperature of dehydrogenation and the hydrogenation reaction enthalpy (Δ H). Furthermore, the operation results in the dehydrogenation activation energy of the alloys distinctly reduced. A comparison of the total results reveals that the favorable impact dedicated by the operation of substitution with Ce to the comprehensive properties of hydrogen storage alloys is more significant than the Sm substitution. [ABSTRACT FROM AUTHOR]

Abstract: The composites of Mg–x wt.% CaNi5 (x =20, 30 and 50) were prepared by hydriding combustion synthesis (HCS) and the phase evolution during HCS as well as the hydriding properties of the products were investigated. It was found that Mg reacted with CaNi5 forming Mg2Ni and Ca during the heating period of HCS. Afterwards, the resultant Mg2Ni and Ca as well as the remnant Mg reacted with hydrogen during the cooling period. The lower platform in the P–C isotherms corresponds to the hydriding of Mg, and the higher one corresponds to Mg2Ni. With the increase of the content of CaNi5 from 20 to 50wt.%, the hydrogen content of the HCS products increases at first and then decreases. The Mg–30wt.% CaNi5 composite has the maximum hydrogen capacity of 4.74wt.%, and it can absorb 3.51wt.% of hydrogen in the first hydriding process without activation. [Copyright &y& Elsevier]

Direct synthesis of Mg2FeH6 was carried out by mechanically alloying MgH2 with Fe under both Ar and H2 atmospheres. Both (3MgH2+Fe) and (4MgH2+Fe) mixtures were processed to improve the yield of Mg2FeH6. The (MgH2–Fe–Cu) system was also investigated to modify the properties of the synthesised compound. X-ray diffraction and Rietveld analysis were carried out to determine the phase evolution of the powder mixtures. Field emission SEM clearly showed substantial particle size reduction for the mixture milled under hydrogen. Thermogravimetry (TG) was employed to determine the dehydrogenation kinetics of the milled mixtures. [Copyright &y& Elsevier]

Mg-based alloy is a promising hydride electrode material. In this study, the kinetics of the electrode reaction of an amorphous Mg50Ni50 hydride electrode is studied by using electrochemical impedance spectroscopy (EIS) technique. An equivalent circuit for the hydride electrode reaction is proposed. Results show that the reaction rate of the hydride electrode is determined by a charge-transfer reaction at the alloy surface, which is represented by the EIS responses in the medium frequency region. The serious corrosion of the active material on the alloy surface is the main reason for the high charge-transfer resistance of the electrode reaction. [Copyright &y& Elsevier]

In order to investigate the effect of the rare earth element Y on the strengthening potency of magnesium alloys and its strengthening mechanism under tension. In this paper, the solid solution structures with Y atom content of 1.8 at.% and 3.7 at.% were built, respectively, and their cohesive energies and stress-strain curve were calculated in the strain range of 0–20%. The calculation results of the cohesive energies showed that the structure of element Y is more stable with the increase of strains. The calculation results of stress and strain showed that Y element can improve the yield strength and tensile strength of the Mg-based alloy, and the strengthening effect is better when the Y content is 3.7 at.%. [ABSTRACT FROM AUTHOR]

Magnesium-based materials are interesting alternatives for medical implants, as they have promising mechanical and biological properties. Thanks to them, it is possible to create biodegradable materials for medical application, which would reduce both costs and time of treatment. Magnesium as the sole material, however, it is not enough to support this function. It is important to determine proper alloying elements and methods. A viable method for creating such alloys is mechanical alloying, which can be used to design the structure and properties for proper roles. Mechanical alloying is highly influenced by the milling time of the alloy, as the time of the process affects many properties of the milled powders. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) were carried out to study the powder morphology and chemical composition of Mg65Zn30Ca4Gd1 powders. Moreover, the powder size was assessed by granulometric method and the Vickers hardness test was used for microhardness testing. The samples were milled for 6 min, 13, 20, 30, 40, and 70 h. The hardness correlated with the particle size of the samples. After 30 h of milling time, the average value of hardness was equal to 168 HV and it was lower after 13 (333 HV), 20 (273 HV), 40 (329 HV), and 70 (314 HV) h. The powder particles average size increased after 13 (31 μm) h of milling time, up to 30 (45–49 μm) hours, and then sharply decreased after 40 (28 μm) and 70 (12 μm) h. [ABSTRACT FROM AUTHOR]

MgNi-based alloys have high electrochemical capacity as anode of nickel-metal hydride (Ni/MH) battery (≥500 mAh g−1). However the capacity decay seriously in charge-discharge cycling, which is previously ascribed to the corrosion of Mg. To solve this problem and reveal the related mechanism, the electrochemcial properties of Mg 0.50 Ni 0.50 , Mg 0.45 Ti 0.05 Ni 0.05 and Mg 0.40 Ti 0.10 Ni 0.50 alloys are studied in combination with their hydrogen storage properties and microstuctural evolution during cycling. This work demonstrates the amorphous phase in milled Mg 0.45 Ti 0.05 Ni 0.50 and Mg 0.40 Ti 0.10 Ni 0.50 alloys has higher resistance to hydrogenation-induced crystallization than milled Mg 0.50 Ni 0.50 alloy. Thus, they show better hydrogen absorption/desorption reversibility and contribute to the reversible electrochemical capacity. Therefore, the cycle performance of the Mg 0.50 Ni 0.50 alloy electrodes shows obvious improvement after partially substituting Mg by Ti. The capacity retention rate increases from 24.0% (Mg 0.50 Ni 0.50) to 55.7% (Mg 0.40 Ti 0.10 Ni 0.50) after 30 cycles. In addition, the Ti addition results in the formation of TiNi phase, and thus, the alloys show better electrochemical reaction kinetics and their high-rate dischargeability (HRD) is significantly improved. At 300 mA g−1, the HRD values of Mg 0.50 Ni 0.50 , Mg 0.45 Ti 0.05 Ni 0.50 and Mg 0.40 Ti 0.10 Ni 0.50 alloys are 41.7%, 83.7% and 90.3%, respectively. At higher discharge current density of 1200 mA g−1, the HRD values are 26.7%, 34.8% and 46.2%, respectively. • Ti addition enhances the stability of the amorphous phase in milled Mg–Ni alloys. • Ti addition results in the formation of TiNi catalytic phase in milled Mg–Ni alloys. • Ti addition improves the electrochemical performances of milled Mg–Ni alloys. [ABSTRACT FROM AUTHOR]

In order to improve the hydrogen storage performances of Mg-based materials, LaMg 11 Ni alloy was prepared by vacuum induction melting. Then the nanocrystalline/amorphous LaMg 11 Ni + x wt% Ni ( x = 100, 200) hydrogen storage alloys were synthesized by ball milling technology. The structure characterizations of the alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage characteristics were tested by using programmed control battery testing system. The electrochemical impedance spectra (EIS), potentiodynamic polarization curves and potential-step curves were also plotted by an electrochemical workstation (PARSTAT 2273). The results indicate that the as-milled alloys exhibit a nanocrystalline and amorphous structure, and the amorphization degree of the alloys visibly increases with extending milling time. Prolonging the milling duration markedly enhances the electrochemical discharge capacity and cyclic stability of the alloys. The electrochemical kinetics, including high rate discharge ability (HRD), charge transfer rate, limiting current density ( I L ), hydrogen diffusion coefficient ( D ), monotonously decrease with milling time prolonging. [ABSTRACT FROM AUTHOR]