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This work covers a Mg-Zn-Ca-Pr alloy fabricated by a novel method of mechanical alloying and spark plasma sintering (SPS). Currently, magnesium alloys used as biomaterials are mostly commercial alloys without consideration of cytotoxicity from the perspective of biosafety. So far, the tribological and cytotoxic properties of Mg-Zn-Ca-Pr alloys have not been investigated. Hence, in the article, the tribological properties, considering wear rate, wear resistance, coefficient of friction, and the roughness of the sintered Mg-Zn-Ca-Pr alloy, are investigated. Cytotoxicity assays have also been carried out. The ball-on-a-disc method is used in the tribological test. Samples before sintering by the SPS method are milled at varying times of 13, 20, and 70 h. Results show that increasing the milling time affects tribology and cytotoxic tests. The longer the milling time, the lower the cell survival rate. The conducted tests reveal cell survival of 90, 82, and 61% for 13, 20, and 70 h, respectively. A reduction of cell viability by over 30% is considered a cytotoxic effect, which was observed only in the 70 h milling-time samples.

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.

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. STATEMENT OF SIGNIFICANCE: 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., Competing Interests: Declaration of Competing Interest All authors declared no conflict of interest., (Copyright © 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The effects of Mn substitution for Mg on the microstructure, mechanical properties, and corrosion behavior of Mg69-xZn27Ca4Mnx (x=0, 0.5 and 1at.%) alloys were investigated using X-ray diffraction, compressive tests, electrochemical treatments, and immersion tests, respectively. Microstructural observations showed that the Mg69Zn27Ca4 alloy was mainly amorphous. The addition of Mn decreases the glass-forming ability, which results in a decreased strength from 545 MPa to 364 MPa. However, this strength is still suitable for implant application. Polarization and immersion tests in the simulated body fluid at 37 °C revealed that the Mn-doped Mg-Zn-Ca alloys have significantly higher corrosion resistance than traditional ZK60 and pure Mg alloys. Cytotoxicity test showed that cell viabilities of osteoblasts cultured with Mn-doped Mg-Zn-Ca alloys extracts were higher than that of pure Mg. Mg68.5Zn27Ca4Mn0.5 exhibits the highest bio-corrosion resistance, biocompatibility and has desirable mechanical properties, which could suggest to be used as biomedical materials in the future., (Copyright © 2013 Elsevier B.V. All rights reserved.)

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]

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]

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]

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]

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]

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 (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]

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]

The microstructures, hydrogen storage thermodynamics and kinetics, and non-isothermal dehydrogenation performances of YMg 11 Ni + 5 wt% M (M = CeO 2 , MoS 2 ) alloys prepared by ball milling were investigated. The results reveal that there exist a nanocrystalline and amorphous structure in all experimental alloys. The CeO 2 catalyzed alloy shows a larger hydrogen absorption capacity and faster hydriding rate as compared with the MoS 2 catalyzed one. The onset hydrogen desorption temperature of M = CeO 2 alloy is lower than that of M = MoS 2 alloy. The hydrogen desorption property of M = CeO 2 alloy is superior to that of M = MoS 2 alloy. The dehydrogenation activation energy ( E de ) is in the order of E de (CeO 2 ) < E de (MoS 2 ), which is responsible for the M = CeO 2 alloy possessing the much faster hydrogen desorption rate. The hydrogen desorption enthalpy change (Δ H de ) is in the order of Δ H de (CeO 2 ) < Δ H de (MoS 2 ). [ABSTRACT FROM AUTHOR]

Reducing particle size and modifying surface state by ball milling are recognized as a useful method to improve the hydrogen absorption kinetics of Mg-based alloys. In order to obtain amorphous and nanocrystalline structures, ball milling was used to process the as-cast La 7 Ce 3 Mg 80 Ni 10 alloy ingot. The effects of ball milling time (5–30 h) on the structures and the thermodynamics and kinetics of hydrogen absorption/desorption of the as-milled alloys were studied. The XRD, SEM and TEM were applied to investigate the structure of the alloys. The Sievert apparatus, DSC and TGA were applied to study the isothermal and non-isothermal properties of hydrogen absorption/desorption. The Arrhenius and Kissinger methods were used to calculate the activation energy of hydrogen desorption. The results indicate that the 10 h-milled alloy has the optimal activation performance and hydrogen absorption/desorption kinetics. Prolonging or shortening the ball milling time results in the impaired hydrogen storage properties. The 10 h-milled alloy in fully activation state can absorb 4 wt% H 2 in 80 s at 473 K and 3 MPa, and it can desorb 3 wt% H 2 in 191 s at 573 K and 1 × 10−4 MPa. The hydrogen desorption enthalpy (Δ H) of the 10 h-milled alloy is 74.21 kJ/mol. Moreover, the 10 h-milled alloy has the smallest apparent activation energy for hydrogen desorption (62.9 kJ/mol), which is the reason why it has the optimal hydrogen storage properties. • The La 7 Ce 3 Mg 80 Ni 10 alloy was successfully prepared and then treated by ball milling. • Prolonging milling time does not lead to continuous improvement in hydrogen storage properties of the alloy. • The La 7 Ce 3 Mg 80 Ni 10 sample milled for 10 h shows the optimal hydrogen storage performance. [ABSTRACT FROM AUTHOR]

In this paper, casting and ball milling procedures were used to create the quaternary alloy La 7 Sm 3 Mg 80 Ni 10 , and the structural evolutions during hydrogen sorption and desorption were investigated and described. According to the findings, ball milling lowers the size of grains and particles while also altering their surface properties. The as-cast alloy absorbs 4 wt% H 2 in 118, 67, and 58 s at 473, 533, and 553 K, respectively, whereas the as-milled alloy takes 108, 56, and 50 s. Additionally, the first hydrogen release temperature of the alloys as-cast and as-milled are 553.9 and 547.4 K, respectively. The as-milled and as-cast alloys had absolute values of the dehydrogenation enthalpy change (Δ H) of 77.13 and 76.52 kJ/mol and apparent activation energies for dehydrogenation (E de) of 80.79 and 78.72 kJ/mol, respectively. • Compared the hydrogen storage property of as-cast and milled alloys. • Ball milling modified the surface state of alloy powders. • Particle size can be decreased by ball milling. • Ball milling decreased the dehydrogenation activation energy of alloys. [ABSTRACT FROM AUTHOR]

The Mg-based alloy with in-situ formed Ti 0.35 V 0.35 Nb 0.2 Cr 0.1 medium-entropy alloy (MEA) nanoparticles was first prepared by a facile mechanochemistry method to resolve its sluggish hydrogen storage kinetics. This novel alloy can absorb a hydrogen capacity of approximately 0.70 wt.% at room-temperature and 2.62 wt.% at 100 ºC with faster kinetics, where its apparent activation energy was greatly decreased to 85.1 kJ mol−1 from 163.7 kJ mol−1 for pure Mg. The in-situ construction of MEA nanoparticles serves as a catalytic agent that was confirmed as an efficient route to improve hydrogen storage kinetics of Mg-based alloy. [Display omitted] [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]

Abstract: Mg- or Ca-based intermetallic compounds of Mg2Ca, Mg2Si, Ca2Si and CaMgSi are investigated as possible new candidates for biodegradable implant materials, attempting to improve the degradation behavior compared to Mg and Ca alloys. The reactivity of Ca can be indeed reduced by the formation of compounds with Mg and Si, but its reactivity is still high for applications as an implant material. In contrast, Mg2Si shows a higher corrosion resistance than conventional Mg alloys while retaining biodegradability. In cytotoxicity tests under the severe condition conducted in this study, both pure Mg and Mg2Si showed relatively high cytotoxicity on preosteoblast MC3T3-E1. However, the cell viability cultured in the Mg2Si extract medium was confirmed to be better than that in a pure Mg extract medium in all the conditions investigated with the exception of the 10% extract medium, because of the lower corrosion rate of Mg2Si. The cytotoxicity derived from the Si ion was not significantly detected in the Mg2Si extract medium in the concentration level of ~70mg/l measured in the present study. For aiming the practical application of Mg2Si as an implant material, however, its brittle nature must be improved. [Copyright &y& Elsevier]

Amorphous CoB was prepared by chemical reduction method. The influence of CoB on the electrochemical properties of MgNi alloy was investigated. MgNi–CoB composite was prepared by mechanical alloying (MA). The cycle life of the electrodes was improved by CoB. The morphology of the material was modified by CoB. The MgNi–CoB (weight ratio 100:15) composite which was MA 15h exhibited the best electrochemical performance. The hydrogen diffusion coefficient in MgNi was increased by CoB . The exchange current density increased with the increasing of CoB (from to ). It was indicated that CoB improved the kinetics of the hydrogenation/dehydrogenation of MgNi-type alloy. The High rate discharge capability (HRD) of the MgNi–CoB composite was higher than that of MgNi. Potentiodynamic polarization results showed that the larger corrosion resistance of MgNi alloys in an alkaline solution which benefited from the introduction of amorphous CoB. The electrochemical impedance test results showed that the values of solution resistance and charge transfer resistance of the MgNi–CoB alloy were reduced by CoB comparing with MgNi. In conclusion, CoB improved the electrochemical performance of the MgNi alloy significantly. [Copyright &y& Elsevier]

Abstract: The hydrogenation properties of the solid–liquid (slurry) system of the F-treated alloy and were investigated. The solid was treated previously with the solution of and deionized water. The concentration of varied from 0.03 to 0.15mol/L in steps. After treatment, a new compound that is snowlake-shaped is wholly covered on the surface of the treated alloy. The XPS and AES analysis indicated that and metallic La are concentrated at the top of the surface and the oxygen content is substantially decreased; and at the outmost layer of the surface, the content of nickel is very low. The appearance of the surface greatly improved the hydrogen absorption of alloy in slurry and the catalytic activity of alloy catalyzing to . The hydrogenation rate of solid–liquid system composed of benzene and F-treated alloy is much higher than the slurry composed of an equal amount of untreated as-cast alloy. Under the best treatment condition, the slurry composed of 20wt% alloy and 80wt% benzene absorbs 6.5mass% hydrogen in 3–4min at 483K and under 4.0MPa hydrogen pressure. [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]

In this work, the multi-element Mg-based alloys, Mg 90 Ce 10 , Mg 90 Ce 5 Ni 5 , Mg 90 Ce 3 Ni 4 Y 3 , were prepared by combination technology of induction smelting and mechanical milling. Meanwhile, the phase evolution in reversible reaction as well as hydrogen storage behaviors of these alloys were investigated in detail by X-ray diffraction, Transmission Electron Microscope, and Pressure-Capacity-Temperature characterization methods. The results showed that the reaction mechanism of the Mg 90 Ce 10 alloy can be concluded as the reversible circulation of Mg/MgH 2 catalyzed by CeH 2.73 phase. After the addition of Ni and Y elements, the new reaction path is introduced in the system, including Mg 2 Ni + H 2 ↔ Mg 2 NiH 4 and YH 2 + H 2 ↔ YH 3. Thereinto, the Ni elements have a very obvious effect on improving the hydrogen absorption and desorption kinetics of the Mg-Ce alloy, which optimizes the optimal hydrogenated temperature to 250 °C and reduces the activation energy of hydrogen desorption from127.3 to 79.7 kJ/mol H 2. Meanwhile, the Ni elements also altered the rate limiting step of hydrogen desorption process of the Mg-Ce alloy from surface control to nucleation and growth control. However, after further addition of Y elements on this basis, the desorption kinetics of the Mg-Ce-Ni-Y-alloy could not be further improved, but its hydrogen absorption kinetics had an obvious enhancement. • New promoting mechanism can be introduced by the multiple alloying. • The Ce, Ni, Y can enhance the hydrogenated behavior of Mg-based alloy step by step. • Y-induced effect are overlaid by that of Ni element for dehydrogenated reaction. • The Mg 90 Ce 3 Ni 4 Y 3 sample can absorb more than 5.5 wt% hydrogen at 250 °C in 5 min. [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 FROM AUTHOR]

To improve hydrogen storage property of Mg-based alloy, the Mg–Ce–Y–Ni + 10 wt % M (M = Zr, Ti, V) composites were prepared by the combination of alloying and ball-milling, and their microstructure, phase evolution, as well as hydrogen storage thermodynamic and kinetic properties, were investigated by XRD, PCT, and DSC methods. The result shows that the hydrogenated samples are composed of MgH 2 , Mg 2 NiH 4 and corresponding ZrH 2 , TiH 2 and VH 1.9 phases. In comparison, the |Δ H| value of M = Ti sample is larger than that of M = Zr and M = V samples, and the M = Ti sample has the highest the peak temperatures and lowest plateau pressure, which indicates that Zr and V elements are more efficient to reduce the thermodynamic stability of RE-Mg-Ni hydrogen storage alloys. Besides, the DSC curve of the M = V sample has another endothermic peak which corresponds to the decomposition reaction between VH 1.9 and VH 0.8 , which has a contribution to desorption kinetic property for the M = V sample. The apparent activation energies (E de) show an increasing trend in the following order: M = Zr (87.7 kJ/mol) < M = V (89.1 kJ/mol) < M = Ti (99.3 kJ/mol). Because the reversible cycle between VH1.9 and VH0.8 provides the driving force to activate the hydrogen desorption of MgH 2, M V sample become an exception of the electronegative rule, and shows better dynamics property than M Ti sample. Image 1 • Mg–Ce–Y–Ni-TM composites are prepared by the combination of alloying and ball-milling. • The Zr and V elements are efficient to disorganize the thermodynamic Mg-based alloy. • The positive role of reversible reaction between the VH 1.9 and VH 0.8 is confirmed. • Activation energy is determined by the both of element property and reaction path. [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]