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Magnesium alloys have become suitable candidates for potential biomedical materials due to their excellent mechanical properties, biocompatibility, and biodegradability. Among different Mg alloys, the Mg–Zn–Ca system is the most popular degradable implant material. The aim of this work is the structure and thermal investigation of the ternary Mg66Zn30Ca4 alloy by a high-energy ball milling process for 5, 8, 13, and 20 h. Morphology changes (SEM) and phase analysis (XRD) of searching materials were investigated. The morphology of the obtained powders and the chemical composition were examined using a scanning electron microscope (SEM) with the energy-dispersive spectrometer (EDS). The distribution of powder size of the samples was determined using the laser particle size analyzer. The thermal characteristics of the powders have been investigated up to 450 °C by differential scanning calorimetry (DSC). Additionally, a microhardness test was carried out. The XRD diffraction patterns of powders show the presence of a solid solution of αMg and the Mg51Zn20 phase. The characteristic Bragg lines of unreacted Zn and Ca can be observed in addition. The DSC analyses showed phase transformations taking place in the alloy. SEM analysis showed a lamellar morphology, which is the result of the deformation process within milling. The results of the microhardness (HV0.05) measuring showed that increasing the milling time improved the microhardness of the Mg66Zn30Ca4 alloy. [ABSTRACT FROM AUTHOR]

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]

Ball milling the powders of Mg-based alloys with transition metal compounds is effective for improving their hydrogen storage performances. In this experiment, the alloys of La 1.7 Y 0.3 Mg 16 Ni + x wt.% TiF 3 (x = 0–10) were prepared through mechanical milling technology. XRD, SEM, HRTEM and granulometry were used to measure the composition and microstructure of alloys. The isothermal hydrogen storage property was measured by a Sievert apparatus. The results reveal that the TiF 3 additive in ball-milled samples transforms into MgF 2 and TiH 2 after the first hydrogen absorption. Adding TiF 3 enhances the crystallinity and reduces the average particle and crystallite sizes of alloys, which is beneficial to accelerating hydriding and dehydriding kinetics. Adding 7 wt% TiF 3 into alloy decreases the dehydrogenation activation energy from 72.2 to 64.0 kJ/mol and improves the hydrogen absorption rate at low temperatures, absorbing 3.50 wt% H in 0.5 min at 323 K. [Display omitted] • La 1.7 Y 0.3 Mg 16 Ni with different TiF 3 additions were prepared by ball milling. • Adding TiF 3 increases crystallinity and decreases average crystallite size of alloys. • MgF 2 and TiH 2 nanocrystals are distributed uniformly on the surface of particles. • 7 wt% TiF 3 -added alloy can absorb 3.50 wt% hydrogen in 0.5 min at 323 K. [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]

Mg-based hydride is a promising hydrogen storage material, but its capacity is hindered by the kinetic properties. In this study, Mg–Mg 2 Ni–LaH x nanocomposite is formed from the H-induced decomposition of Mg 98 Ni 1·67 La 0.33 alloy. The hydrogen capacity of 7.19 wt % is reached at 325 °C under 3 MPa H 2 , attributed to the ultrahigh hydrogenation capacity in Stage I. The hydrogen capacity of 5.59 wt % is achieved at 175 °C under 1 MPa H 2. The apparent activation energies for hydrogen absorption and desorption are calculated as 57.99 and 107.26 kJ/mol, which are owing to the modified microstructure with LaH x and Mg 2 Ni nanophases embedding in eutectic, and tubular nanostructure adjacent to eutectic. The LaH 2.49 nanophase can catalyze H 2 molecules to dissociate and H atoms to permeate due to its stronger affinity with H atoms. The interfaces of these nanophases provide preferential nucleation sites and alleviate the "blocking effect" together with tubular nanostructure by providing H atoms diffusion paths after the impingement of MgH 2 colonies. Therefore, the superior hydrogenation properties are achieved because of the rapid absorption process of Stage I. The efficient synthesis of nano-catalysts and corresponding mechanisms for improving hydrogen storage properties have important reference to related researches. [Display omitted] • The hydrogenation activation energy of Mg–Mg 2 Ni–LaH x composite is reduced to 57.99 kJ/mol. • The enhanced hydrogenation capacities at 325 °C and 175 °C are 7.19 wt % and 5.59 wt %, respectively. • In-situ formed LaH 2.49 nanophase is proved to catalyze the hydrogenation process. • High-density tubular nanostructure alleviates the "blocking effect" by facilitating H diffusion. [ABSTRACT FROM AUTHOR]

Using two different types of protective coatings, we examined the protection of magnesium alloy (AZ61) with composition of Mg(93)–Al(6) –Zn(1) against corrosion in neutral 3.5% NaCl solution. We treated the alloy with a novel silane polymer coating that demonstrated viable in protecting the surface against corrosion. The hybrid protecting film is composed of 1,2 bis(triethoxysilyl)ethane-poly(vinyl alcohol). Also we examined an alternative approach to coat the magnesium-based alloy with a layer containing nickel and TiO2 nanoparticles and followed by applying a protective silane film. The silane film was synthesized from a silane precursor (1,2-bis(triethoxysilyl)ethane) using a sol–gel cross-linking method. The surface of the bare and coated Mg alloy was evaluated before and after exposure to the corrosive medium using structural, surface and electrochemical techniques. Structural techniques include X-ray photoelectron spectroscopy. Scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis was used to explore the surface morphologies and structures. The electrochemical techniques used were potentiodynamic polarization and electrochemical impedance spectroscopy. The Mg alloy coated with the hybrid films has been tested for prolonged exposure to the chloride solution, and both coatings have proved effective in protecting the Mg alloy. [ABSTRACT FROM AUTHOR]

Mg-based biodegradable metallic implants are gaining increased attraction for applications in orthopedics and dentistry. However, their current applications are hampered by their high rate of corrosion, degradation, and rapid release of ions and gas bubbles into the physiological medium. The aim of the present study is to investigate the osteogenic and angiogenic potential of coated Mg-based implants in a sheep cranial defect model. Although their osteogenic potential was studied to some extent, their potential to regenerate vascularized bone formation was not studied in detail. We have studied the potential of magnesium-calcium (MgCa)-based alloys modified with zinc (Zn)- or gallium (Ga)-doped calcium phosphate (CaP) coatings as a strategy to control their degradation rate while enhancing bone regeneration capacity. MgCa and its implants with CaP coatings (MgCa/CaP) as undoped or as doped with Zn or Ga (MgCa/CaP + Zn and MgCa/CaP + Ga, respectively) were implanted in bone defects created in the sheep cranium. MgCa implants degraded faster than the others at 4 weeks postop and the weight loss was ca. 50%, while it was ca. 15% for MgCa/CaP and <10% in the presence of Zn and Ga with CaP coating. Scanning electron microscopy (SEM) analysis of the implant surfaces also revealed that the MgCa implants had the largest degree of structural breakdown of all the groups. Radiological evaluation revealed that surface modification with CaP to the MgCa implants induced better bone regeneration within the defects as well as the enhancement of bone-implant surface integration. Bone volume (%) within the defect was ca. 25% in the case of MgCa/CaP + Ga, while it was around 15% for undoped MgCa group upon micro-CT evaluation. This >1.5-fold increase in bone regeneration for MgCa/CaP + Ga implant was also observed in the histopathological examination of the H&E- and Masson's trichrome-stained sections. Immunohistochemical analysis of the bone regeneration (antiosteopontin) and neovascularization (anti-CD31) at the defect sites revealed >2-fold increase in the expression of the markers in both Ga- and Zn-doped, CaP-coated implants. Zn-doped implants further presented low inflammatory reaction, notable bone regeneration, and neovascularization among all the implant groups. These findings indicated that Ga- and Zn-doped CaP coating is an important strategy to control the degradation rate as well as to achieve enhanced bone regeneration capacity of the implants made of Mg-based alloys.

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.

The rare earth elements are believed to catalyze the reversible reaction between magnesium and hydrogen and reduce the thermal stability of MgH 2 by weakening the Mg–H bond. This study focuses on investigating the effect of Ce partial substitution of La on the comprehensive hydrogen storage performances of La 10- x Ce x Mg 80 Ni 10 (x = 0–4) alloys (prepared by vacuum induction melting). The phase composition and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM). The thermodynamics and kinetics of isothermal reactions were measured by the automatic Sievert apparatus. Non-isothermal dehydrogenation performance of the alloys was researched by thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). All the experimental alloys have a large capacity of hydrogen absorption and desorption and the kinetics of the Ce containing alloys is better. The additive Ce exists in the solid solution of alloy and results in the refinement of grain, making the stability of the hydride visibly lower, which is the reason for the decline in the initial dehydrogenation temperature and enthalpy (Δ H) of the hydride. Besides, the dehydrogenation activation energy of the alloys is distinctly reduced by composition adjustment, which indicates the improved hydrogen storage performances. • The as-cast La 10- x Ce x Mg 80 Ni 10 (x = 0–4) alloys were prepared by induction melting. • Ce substitution of La optimizes the activation performance of experimental materials. • Substituting La with Ce weakens the stability of Mg-based hydrides. • Adding Ce is beneficial for improving the kinetics of experimental alloys. [ABSTRACT FROM AUTHOR]

The Mg-based hydrogen storage alloy with multiple platforms is successfully prepared by ball milling Co powder and Mg-RE-Ni precursor alloy, and its hydrogen storage behavior was investigated in detail by XRD, EDS, TEM, PCI, and DSC methods. The ball-milled alloy consists of the main phase Mg, the catalytic phases Mg 2 Ni, Mg 2 Co as well as a small amount of Mg 12 Ce, and convert into the MgH 2 –CeH 2.73 -Mg 2 NiH 4 –Mg 2 CoH 5 composite after hydrogenation. The composite has three PCI platforms corresponding to the reversible de/hydrogenation reaction of Mg/MgH 2 , Mg 2 Ni/Mg 2 NiH 4 and Mg 6 Co 2 H 11 /Mg 2 CoH 5. Among them, the transformation between Mg 2 Ni and Mg 2 NiH 4 triggers the "spill-over" effect which promote the decomposition of MgH 2 phases and enhances the hydrogen desorption kinetics. Meanwhile, the conversion of the Mg 6 Co 2 H 11 to Mg 2 CoH 5 phase induces the "chain reaction" effect, which leads to preferential nucleation of Mg phase and improves the hydrogen absorption kinetics. Therefore, the Mg-RE-Ni-Co alloy has a double improvement on hydrogen absorption and desorption kinetics. Concretely, the alloy has an optimal hydrogen absorption temperature of 200 °C, at which it can absorb 5.5 wt. % H 2 within 40 s. Under the conditions, the capacity of absorption almost reaches the maximum reversible value (about 5.6 wt. %). Besides, the alloy has a dehydrogenation activation energy of 67.9 kJ/mol and can desorb 5.0 wt. % H 2 within 60 min at the temperature of 260 °C. • The Mg-based hydrogen storage alloy with multiple platforms is successfully prepared. • The Ni-/Co-multi-platform collaborative system is built. • The Mg-RE-Ni-Co alloy has a double improvement in hydrogen absorption and desorption. • The alloy can absorb 5.5 wt. % H 2 within 40 s at 200 °C. • The dehydrogenation activation energy is evaluated to be 67.9 kJ/mol. [ABSTRACT FROM AUTHOR]

Biodegradable magnesium (Mg)-based alloys emerge as potential intracorporeal implants for clinical application in bone tissue, the cardiovascular and the nervous systems. The surfaces of control (non-sterilized) and sterilized (180 °C 1 h) Mg ZX10 alloy were studied. The alloy evolution in SBF (simulated saline solution) and in DMEM (Dulbecco's Modified Eagle Medium) with fetal calf serum (FCS) was investigated using: Raman spectroscopy, FTIR-ATR, electrochemical assays and scanning electron microscopy (SEM). The Mg ZX10 microstructure analysis revealed an average grain size of 23.4 ± 11.02 and 31.6 ± 13.07 μm, considering the minor and major axis, respectively. In addition, the Mg ZX10 microstructure exhibited a homogeneous grain distribution. The contact angle formed between the water and the surface of control Mg ZX10 and sterilized were 32.24° ± 1.53 and 46.76° ± 0.83, respectively. Consequently, both groups of samples exhibited hydrophilic surfaces. Furthermore, the free surface energy of control Mg ZX10 was 63.23 ± 0.72 mN/m and sterilized Mg ZX10 was 52.31 mN/m ± 1.25, those energy values were in agreement with previous reports. Upon immersion in SBF, Raman spectroscopy detected the presence of magnesium oxides-hydroxides, phosphates and carbonates compounds in both groups of samples without significant differences. FTIR spectra of the sterilized alloys, after immersion in DMEM + FCS, showed the presence of amide and carbon-carbon bonds, magnesium-oxides, as well as phosphates and carbonates groups. These findings suggested the deposition of organic and inorganic compounds on the alloy surface. Electrochemical assays carried out in SBF demonstrated a slight reduction in the degradation of the sterilized alloy compared to control Mg ZX10. Moreover, a substantial decrease in the corrosion behavior of the sterilized alloy immersed in DMEM + FCS with respect to the same alloy immersed in SBF was observed. SEM images showed that the alloy, previously immersed in SBF, exhibited degradation cracks. Contrary, the sterilized alloy surface immersed in DMEM + FCS was more homogenous with deposits of structures similar to hybrid nanoflowers. Based on these results, this sterilization process does not alter the chemistry of Mg ZX10 alloy surface and, even, its application exhibits an advantage since the high corrosion rate of Mg in physiological media. Furthermore, the organic-inorganic structures adsorbed, after alloy immersion in DMEM + FCS, could decrease corrosion behavior. • The sterilization (180 °C 1 h) does not modify the chemical surface of Mg ZX10. • The sterilized alloys exhibit a slight less corrosion in SBF than non-sterilized. • The hybrid structures on the Mg ZX10 surface would improve its corrosion behavior. • The nanoflowers could serve for designing surface modification for Mg ZX10 alloy. [ABSTRACT FROM AUTHOR]

In this work, the Mg 90 Y 1.5 Ce 1.5 Ni 7 sample is successfully prepared by combining the vacuum induction melting and the mechanical milling. The phase composition and microstructure characteristics are studied by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy measurements. The hydrogenated sample is composed of MgH 2 , Mg 2 NiH 4 , CeH 2.73 phases, whereas only the MgH 2 and Mg 2 NiH 4 phases are decomposed during dehydrogenation. The hydrogen storage properties of Mg 90 Y 1.5 Ce 1.5 Ni 7 samples are measured by semi-automatic Sievert type apparatus. It is found that the samples could be fully activated within three cycles of absorption and dehydrogenation, with a reversible hydrogen storage capacity of about 5.6 wt%. Also, the "optimal hydrogenation temperature" is reduced to 200 °C, and the dehydrogenation activation energy is calculated to be 68.2 kJ/mol and 65.8 kJ/mol by using the Arrhenius and Kissinger equations, respectively. This work provides a scientific approach to promote the practical application of Mg-based alloy. • Samples were prepared by combining the induction melting and the mechanical milling. • The hydrogenated Mg 90 Y 1.5 Ce 1.5 Ni 7 sample has a nanocrystalline structure. • The "optimal hydrogenation temperature" was reduced to 200 °C through ball milling. • The dehydrogenation activation energy is evaluated to be 65.8 kJ/mol. [ABSTRACT FROM AUTHOR]

Transition metals and rare-earth elements have excellent catalytic effects on improving the de-/hydrogenation properties of Mg-based alloys. In this study, a small amount of La is used to substitute the Ni in Mg 98 Ni 2 alloy, and some Mg 98 Ni 2- x La x (x = 0, 0.33, 0.67, and 1) alloys show the better overall hydrogen storage properties. The effects of La on the solidification and de-/hydrogenation behaviors of the alloys are revealed. The results indicate that different factors dominate the processes of hydrogen absorption and desorption. The Mg 98 Ni 1·67 La 0.33 alloy absorb 7.04 wt % hydrogen at 300 °C, with the highest isothermal absorption rate, the Mg 98 Ni 1·33 La 0.67 hydride show the highest isothermal desorption rates and the lowest peak desorption temperature of 327 °C. The La addition can increase the driving force of hydrogenation, thus the hydrogenation rates and capacities of the Mg 98 Ni 1·67 La 0.33 and Mg 98 Ni 1·33 La 0.67 alloys are improved. The formation of refined eutectic structures is a key factor that facilitates the desorption processes of the Mg 98 Ni 2- x La x hydrides with x = 0.67 and 1. High-density LaH 3 nanophses are in-situ formed from the LaMg x (8.5 < x < 12) phase, which results in the improved de-/hydrogenation properties. The further La addition deteriorates the hydrogen storage properties of Mg 98 Ni 2- x La x alloy. • La addition can improve the hydrogen storage properties of Mg 98 Ni 2- x La x alloy. • Mg 98 Ni 1.67 La 0.33 alloy has a hydrogen capacity of 7.04 wt. % with fast absorption rate. • The peak desorption temperature of Mg 98 Ni 1.33 La 0.67 hydride is reduced to 327C from 394 °C. • The refined eutectic in Mg 98 Ni 1.67 La 0.33 and Mg 98 Ni 1.33 La 0.67 alloys facilitate the desorption 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.

Mechanical milling is widely recognized as the best method to prepare nano-structured magnesium based hydrogen storage materials. The composites La 7 Sm 3 Mg 80 Ni 10 + 5 wt% TiO 2 (named La 7 Sm 3 Mg 80 Ni 10 –5TiO 2) whose structures are nano-crystal and amorphous accompanied by great hydrogen absorption and desorption properties were fabricated by mechanical milling. The research focuses on the effect of milling duration on the thermodynamics and dynamics. The instruments of researching the gaseous hydrogen storing performances include Sievert apparatus, DSC and TGA. The calculation of dehydrogenation activation energy was realized by applying Arrhenius and Kissinger formulas. The calculation results show the specimen milled for 10 h exhibits the optimal activation performance and hydrogenation and dehydrogenation kinetics. Extending or shrinking the milling duration will lead to the degradation of hydrogen storage performances. The as-milled (10 h) alloy at the full activated state can absorb 4 wt% hydrogen in 87 s at 473 K and 3 MPa and release 3 wt% H 2 in 288 s at 573 K and 1 × 10−4 MPa. The changed milling durations have little impact on the thermodynamic properties of experimental samples and the enthalpy change (Δ H) of the alloy milled for 10 h is 74.23 kJ/mol. Moreover, it is found that the as-milled (10 h) alloy displays the minimum apparent activation energy of dehydrogenation (59.1 kJ/mol), suggesting the optimal hydrogen storing property of the as-milled (10 h) alloy. • The composite La 7 Sm 3 Mg 80 Ni 10 + 5 wt% TiO 2 was prepared by mechanical milling. • The effect of milling time on hydrogen storage property was investigated. • Hydriding and dehydriding rates can be affected by milling time. • The as-milled (10 h) alloy shows the optimal gaseous hydrogen storage performance. [ABSTRACT FROM AUTHOR]

Element replacement and mechanical milling are considered as the most effective ways to improve Mg-based alloys in their hydrogen storage performance. The as-milled La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys were prepared in this experiment by introducing both element replacement (replacing La by Ce or Sm partially) and mechanical milling technologies. The influence made by different replacing elements on the structure and hydrogen storage property of La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys was investigated in detail. X-ray diffraction, transmission electron microscope, automatic Sievert apparatus, thermogravimetry and differential scanning calorimetry were used to investigate the experimental alloys. The experiment reveals that a nanocrystalline and amorphous structure appears after mechanical milling. Moreover, comparing with the RE = Sm alloy, the RE = Ce alloy has a superior hydrogen desorption property, including larger hydrogen absorption capacity, faster hydriding/dehydriding rate, lower onset hydrogen desorption temperature, and lower dehydrogenation activation energy. • La 7 RE 3 Mg 80 Ni 10 (RE = Sm, Ce) alloys were prepared by ball milling. • Substituting La by Sm or Ce does not change the microstructure of alloys. • Replacing La by Ce weakens the stability of alloys more effectively then by Sm. • RE = Ce alloy shows better hydrogen desorption kinetics than RE = Sm alloy. [ABSTRACT FROM AUTHOR]

Element substitution is an effective strategy for improving Mg-based alloys in their hydrogenation/dehydrogenation property. Thereby, in this paper, Sm was selected to partially replace La in a La–Mg-based alloy for improving its hydriding and dehydriding performance. The alloys with the compositions of Mg 80 Ni 10 La 10- x Sm x (x = 0–4) were manufactured through vacuum induction melting. Their microstructures and phase compositions were measured by XRD, SEM and HRTEM. The isothermal hydrogen storage property was tested through an automatic Sieverts apparatus. Non-isothermal hydrogen desorption performance was measured through TGA and DSC. Arrhenius and Kissinger methods were adopted to calculate the dehydrogenation activation energy of alloys. The results reveal that all of the experimental alloys can reversibly absorb and release a large amount of H 2 at appropriate temperatures. The substitution of Sm for La ameliorates the hydriding and dehydriding kinetics, but it results in an undesired reduction of hydrogen absorption and desorption capacities. Substituting La by Sm decreases the initial hydrogen release temperature of the hydride visibly. Furthermore, substituting Sm for La engenders the dehydrogenation activation energy decline clearly, which is considered as the main reason for the improved hydrogen desorption kinetics resulted from Sm replacing La. • Mg 80 Ni 10 La 10- x Sm x (x = 0–4) alloys were prepared in a vacuum induction furnace. • Sm substituting La improves the activation property of experimental alloys. • Sm substituting La reduces the initial hydrogen release temperature of alloys. • Increasing Sm content declines the dehydrogenation activation energy obviously. [ABSTRACT FROM AUTHOR]

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]

Nanostructuring and catalyzing are effective methods for improving the hydrogen storage properties of MgH 2. In this work, transition-metal-carbides (TiC, ZrC and WC) are introduced into Mg–Ni alloy to enhance its hydrogen storage performance. 5 wt% transition-metal-carbide containing Mg 95 Ni 5 (atomic ratio) nanocomposites are prepared by mechanical milling pretreatment followed by hydriding combustion synthesis and mechanical milling process, and the synergetic enhancement effects of Mg 2 NiH 4 and transition-metal-carbides are investigated systematically. Due to the inductive effect of Mg 2 NiH 4 and charge transfer effect between Mg/MgH 2 and transition-metal-carbides, Mg 95 Ni 5 -5 wt.% transition-metal-carbide samples all exhibit excellent hydrogen storage kinetic at moderate temperature and start to release hydrogen around 216 °C. Among them, 2.5 wt% H 2 (220 °C) and 4.7 wt% H 2 (250 °C) can be released from the Mg 95 Ni 5 -5 wt.% TiC sample within 1800 s. The unique mosaic structure endows the Mg 95 Ni 5 -5 wt.% TiC with excellent structural stability, thus can reach 95% of saturated hydrogen capacity within 120 s even after 10 cycles of de-/hydrogenation at 275 °C. And the probable synergistic enhancement mechanism for hydrogenation and dehydrogenation is proposed. Image 1 • TiC, ZrC, WC were employed to improve the hydrogen storage properties of Mg 95 Ni 5. • Charge transfer effect between Mg/MgH 2 and TMCs facilitates the dehydrogenation. • Synergetic effects of Mg 2 NiH 4 and TMCs were investigated in depth. • HCS + MM-Mg 95 Ni 5 -5 wt.% TiC composite exhibits excellent cycle stability. [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.%.

Summary: In this study, the metallurgical melting Mg‐10wt.%Ni (Mg10Ni) alloy is firstly modified by high‐energy ball milling (HEBM) and then surface catalysts expanded graphite (EG) or MoS2 or EG‐MoS2 are introduced to prepare Mg10Ni‐M (M = EG, MoS2, and EG‐MoS2) composites. The effects of surface catalysts on hydrolysis hydrogen generation of HEBM Mg10Ni alloy are comprehensively investigated. Their kinetics, rate‐limiting steps, and apparent activation energies are investigated by fitting the hydrolysis curves at different temperatures. The results indicate that the total hydrogen generation capacities of prepared Mg10Ni‐M (M = EG, MoS2, and EG‐MoS2) composites are 200, 170, 674, and 720 mL·g−1 within 1 minute at 291 K. The capacity and yield of Mg10Ni are 500 mL·g−1 and 56% within 15 minutes. The surface catalysts EG or MoS2 or EG‐MoS2 can distinctly elevate the initial H2 produce rate and promote the complete hydrolysis process. The highest capacity and generation yield within 15 minutes are 740.8 mL·g−1 and 91% obtained by HEBM Mg10Ni‐EG‐MoS2 composite at 291 K. The surface catalysis can promote high generation yield of Mg10Ni alloy in a short time. [ABSTRACT FROM AUTHOR]

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 Mg-Zn-Ca bulk metallic glasses (BMGs) have been regarded as new biodegradable materials for orthopedic implants, while size constrains limit their biomedical applications. In this study, Mg-based amorphous layers with the nominal composition of Mg 65 Zn 30 Ca 5 have been successfully produced using the laser remelting method. The influences of laser scanning speed on the microstructural characteristics of Mg-Zn-Ca amorphous layers during laser remelting process were investigated systematically by experiments and numerical simulations. Amorphous phase could be formed when the laser scanning speed was kept above 1000 mm/min. The remelted layer mainly consisted of a gradient structure: amorphous-crystalline composite layer, transitional layer and crystalline substrate. The increase of the laser scanning speed was benefit to improve the corrosion resistance of the remelted layer due to the formation of amorphous structure. Analysis of the temperature distributions and related thermal profiles simulated using the finite element method indicated that the crystallization could be suppressed with the increase of the laser scanning speed, which would shorten the residence time and leads to higher cooling rate in this process as well. Highlights • Laser remelting is an effective technique to fabricate Mg-Zn-Ca amorphous coatings. • The effect of laser scanning speed on the microstructure of the coatings was investigated. • Increasing laser scanning speed is beneficial for the formation of amorphous phase. • Crystallization occurs in the HAZ rather than in the remelted region. [ABSTRACT FROM AUTHOR]

Abstract Mg 80– x Ni 20 Y x (x = 0–7) alloys were successfully prepared by using the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy measurements. The effects of yttrium content on the microstructure and hydrogen storage properties of the as-cast alloys were investigated. The alloys are composed of a primary phase of Mg 2 Ni, lamella eutectic composites of Mg + Mg 2 Ni, and some amount of YNi 3. The YNi 3 has completely transformed into in situ formed nanoscale YH 2 and YH 3 , with the formation of Mg 2 NiH 4. Pulverization of the alloy particles was observed during the hydrogen absorption and desorption cycles. However, the phase composition remains unchanged even after 20 hydrogenation cycles. Yttrium addition significantly improved the hydrogen-absorption kinetic performance of the alloy. In addition, pressure-composition-temperature measurements indicated that the entropy and enthalpy changes for the formation and decomposition of MgH 2 and Mg 2 NiH 4 gradually decreased with the increase of yttrium content. Highlights • YNi 3 , Mg 2 Ni and lamella eutectic Mg + Mg 2 Ni phases were observed in the alloys. • YNi 3 fully decomposed, with the formation of nanometer YH 2 and Mg 2 NiH 4. • Increasing Y content significantly improves the hydrogen absorption kinetics. • The decomposition peak temperature was reduced from 586 K to 523 K. • Δ H and Δ S of the Mg/MgH 2 and Mg 2 Ni/Mg 2 NiH 4 transformations decreased. [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]

Abstract In order to improve the hydrogen storage properties of Mg-based materials, ternary Mg 24 Y 3 –3 wt.% graphite (C)– x wt.% Ni (x = 0–20) nanocomposites were synthesized by mechanical ball-milling. Micro-area elemental analysis shows that the Ni and C are evenly distributed in the samples. Effect of Ni content on hydrogen absorption and desorption behavior at various temperatures was performed. Hydrogenation leads to the in situ formation of YH 2 /YH 3 and Mg 2 Ni/Mg 2 NiH 4 , which has a significant catalytic effect on the hydrogen absorption and desorption kinetics. Composites with more than 3 wt% of Ni can almost reach their maximum hydrogen storage capacity within 1 min at 100 °C. When the Ni content increases from 0 to 20 wt%, the dehydrogenation activation energy (E a) is reduced to 58 kJ/mol, while the desorption peak temperature is also lowered down to 282 °C. Two equilibrium plateaus are clearly observed in pressure–composition isotherms (p – c – T) curves, which can be ascribed to the hydrogen absorption/desorption reactions of Mg/MgH 2 and Mg 2 Ni/Mg 2 NiH 4. In order to take account to the reversible hydrogen storage capacity and absorption/desorption kinetics, Mg 24 Y 3 –3 wt.% C–5 wt.% Ni composite is considered having the optimized hydrogen storage performance. Graphical abstract Image Highlights • Nanostructured Mg–Y–C–Ni composites are prepared by mechanical ball-milling. • Hydrogenation leads to the in situ formation of YH 2 and Mg 2 NiH 4. • The composites can absorb about 5 wt% of hydrogen within 30 s at 100 °C. • Increasing Ni content significantly promotes the hydriding and dehydriding kinetics. [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]

Abstract Magnesium-based materials have promising mechanical properties and potential to serve as implants for loadbearing temporary applications. The main concern about such implants is their strength and resistance for the acting forces. In this investigation, magnesium-based biodegradable Mg 65 Zn 30 Ca 4 Gd 1 alloy prepared by combination of innovative Mechanical Alloying (MA) and Spark Plasma Sintering (SPS) methods, was studied for the structure and mechanical properties. Structural studies were performed using X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). XRD studies were conducted to gain an overview of the phase composition in powdered and sintered samples. The energy dispersive spectroscopy (EDS) additionally determine the chemical composition of the samples. SEM observations were used to examine the morphology of the sinters on the fractured surface after the compressive tests. Mechanical properties of the Mg 65 Zn 30 Ca 4 Gd 1 alloy were examined by compressive tests, to determine the compressive strength and Young's modulus of the samples at room temperature. The paper provides information about the density and porosity of the Mg-based alloy and additionally its corrosion resistance. Moreover the work shows advantages and possibilities of forming multi-compound, morphologically homogeneous alloys with high mechanical properties in the powder metallurgy processes. [ABSTRACT FROM AUTHOR]

In this article, the isothermal hydrogenation curves of hypo-eutectic Mg–6Ni–3Cu (at. %) alloy under various temperatures and applied hydrogen pressures are fitted by Johnson-Mehl-Avrami equation. The hydrogenation behavior and its dependence on absorption conditions are investigated, as different from that of pure Mg. A three-stage hydrogenation behavior is illustrated and an extra absorption process (Stage III) resulted from H dissolution or the hydride formation in boundaries appears when the hydrogen pressure reaches a critical value. Due to the same role of increased Δ P and decreased Δ T on hydride nucleation driving force and their opposite impacts on H diffusion, temperature and hydrogen pressure are influencing the absorption process differently. As the great H permeability in Mg–Mg 2 Ni–Mg 2 Cu eutectic, more hydrogen is absorbed under larger hydrogenation driving force, rather than hydrogen uptake deficit. It is revealed that the reaction order η corresponding to H diffusing in thin MgH 2 layer is larger than that in thick MgH 2 shell, which can preliminarily identify the hydrogenation behavior after MgH 2 impinging around primary Mg (Stage II). [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]