Hydrogen permeation through magnesium

Nishimura, Chikashi; Komaki, M.; Amano, Muneyuki

doi:10.1016/s0925-8388(99)00373-4

Cited by 75 publications

(41 citation statements)

References 3 publications

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“…The higher value 0.21 eV is the actual energy barrier for the long-range diffusion. These values are consistent with experimental results [96,97]. Along the partial dislocation core of Mg, the QM/MM results show that the barriers slightly increase to 0.22 eV and 0.26 eV for the screw and edge dislocation respectively.…”

Section: Hydrogen Diffusionsupporting

confidence: 81%

Multiscale Modeling of Hydrogen Embrittlement

Zhang

Lü

2015

Molecular Modeling of Corrosion Processes

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Section: Hydrogen Diffusionsupporting

confidence: 81%

Multiscale Modeling of Hydrogen Embrittlement

Zhang

Lü

2015

Molecular Modeling of Corrosion Processes

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“…Nishimura et al [31] showed that the solubility of H in pure Mg in the temperature range 200°C to 220°C and the pressure range 0.1 to 10 kPa obeys Sievert's Law. Thus, assuming that the hydrogen pressure is equal to the hydrogen fugacity, and that under charging conditions, H absorption is unimpaired by surface films or the formation of a hydride layer, the equilibrium concentration in the specimen is …”

Section: A H 2 Chargingmentioning

confidence: 97%

Fractography of Stress Corrosion Cracking of Mg-Al Alloys

Winzer

Atrens

Dietzel³

et al. 2008

Metall Mater Trans A

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Mechanisms for the stress corrosion cracking (SCC) of Mg-Al alloys have been investigated by scanning electron microscopy (SEM) of the fracture surfaces, for the two-phase alloy AZ91 and the single-phase alloys AZ31 and AM30 in distilled water. The mechanism for crack initiation in AZ31 and AM30 involves localized dissolution. The mechanisms for crack propagation in AZ31 and AM30 involve microvoid coalescence and cleavage, respectively. The mechanism for crack initiation in AZ91 is unclear, but may involve the fracture of b particles near the surface. The mechanism for crack propagation at moderate strain rates in AZ91 is similar to that in AZ31, with b particles acting as sources of H for mobile dislocations. The fracture surface for AZ91 tested at the strain rate 3 · 10 -8 s -1 was similar to that for specimens precharged in gaseous H 2 . This fracture surface is the result of (1) the nucleation and growth of MgH 2 particles, (2) sudden fracture through the MgH 2 particles at some critical stress, and (3) decomposition of the MgH 2 particles after fracture.

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“…Figure 1 illustrates schematically the morphology of a free-standing film and a cross-sectional SEM image, which shows that the Mg-Ni layer is dense and composed of nanostructured nanosized grains structures. It is known that the diffusivity of hydrogen along the boundaries of grains is much faster than through the bulk; room-temperature pulsed laser deposition thus enables the realization of such desirable nanostructured morphology [23].…”

mentioning

confidence: 99%

Hydrogen storage characteristics of nanograined free-standing magnesium–nickel films

et al. 2009

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Free-standing magnesium-nickel (Mg-Ni) films with extensive nanoscale grain structures were fabricated using a combination of pulsed laser deposition and film delaminating processes. Hydrogen sorption and desorption properties of the films, free from the influence of substrates, were investigated. Oxidation of the material was reduced through the use of a sandwiched free-standing film structure in which the top and bottom layers consist of nanometerthick Pd layers, which also acted as a catalyst to promote hydrogen uptake and release. Hydrogen storage characteristics were studied at three temperatures, 296, 232, and 180°C, where multiple sorption/desorption cycles were measured gravimetrically. An improvement in hydrogen storage capacity over the bulk Mg-Ni target material was found for the free-standing films. As shown from a Van't Hoff plot, the thermodynamic stability of the nanograined films is similar to that of Mg 2 Ni. These results suggest that free-standing films, of which better control of material compositions and microstructures can be realized than is possible for conven- The need for a safe, reliable, and efficient method of hydrogen storage for transportation applications is stronger now than ever before. This need has led to a continuous increase in both the breadth and depth of research in the field of hydrogen storage. Compressed gas, liquid hydrogen, and various chemical and metal hydride approaches have been proposed and studied over the past 20 years [1]. Despite extensive research effort, no definitive best method or best material has been identified. Weaknesses and difficulties for every method and material exist. Examples are the poor volumetric storage of hydrogen as a compressed gas, the boil off of liquid hydrogen, the poor irreversibility of chemical and metal hydrides [2].Metal hydrides consisting of a high fraction of lightweight elements have attracted much attention. The basic storage mechanisms of hydrogen by physisorption and chemisorption as well as the importance of catalysts have been elucidated [3][4][5]. More recently, the benefits of using nanometer-sized materials have also been explored [6][7][8]. Through nanostructuring, improvements in hydrogen uptake and release kinetics at little cost to hydrogen sorption capacities are possible. There are, however, very few material synthesis approaches that can generate a sufficient quantity of nanostructured light-weight metals (which are generally reactive upon exposure toward air and water) for reliable testing of their hydrogen storage properties. The majority of existing studies of metal hydrides are based on the characterization of ball-milled powders. For many materials of

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Hydrogen permeation through magnesium

Cited by 75 publications

References 3 publications

Multiscale Modeling of Hydrogen Embrittlement

Multiscale Modeling of Hydrogen Embrittlement

Fractography of Stress Corrosion Cracking of Mg-Al Alloys

Hydrogen storage characteristics of nanograined free-standing magnesium–nickel films

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