Influence of steel on the mechanical stress development during hydrogen-loading of ultrathin Nb-films

Klose, Philipp; Hamm, Magnus; Roddatis, Vladimir; Pundt, Astrid

doi:10.1016/j.ijhydene.2017.04.229

Cited by 5 publications

(3 citation statements)

References 28 publications

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“…This situation is visualized in Figure a. TEM‐studies revealed a columnar domain structure with highly coherent interfaces between the two phases . The hydrogen solubility of μ‐FeNb is negligible, resulting in the desired stabilizing internal frame of the Nb film.…”

Section: Resultsmentioning

confidence: 95%

Structural Phase Transitions in Niobium Hydrogen Thin Films: Mechanical Stress, Phase Equilibria and Critical Temperatures

et al. 2019

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Metal−hydrogen (M−H) systems offer grand opportunities for studies on fundamental aspects of thermodynamics and kinetics. When the system size is reduced to the nanoscale, microstructural defects as well as mechanical stress affect the systems’ properties. This is contemplated for the model system of epitaxial niobium−hydrogen (Nb−H) thin films. Hydrogen absorption in metals commonly leads to lattice expansion which is hindered when the metal adheres to a flat rigid substrate. Consequently, high mechanical stress of about −10 GPa for 1 H/Nb are predicted, in theory. However, metals cannot yield such high stresses and respond with plastic deformation, commonly limiting measured stresses to −2 to −3 GPa for 100 nm Nb−H films. It will be shown that the coherency state changes with film thickness reduction, shifting the onset of plastic deformation to larger hydrogen concentrations. Below critical film thicknesses, plastic deformation is fully absent. The system then behaves purely elastic and ultra‐high stress of about −10 (±2) GPa can be obtained. Arising stress controls the phase stability of M−H systems, and the coherency state strongly affects the nucleation and growth dynamics of the phase transition. In case of Nb−H thin films of less than 8 nm thickness the common phase transformation from the α‐phase solid solution to the hydride phase is completely suppressed at 300 K. Related effects can be utilised to optimise metal−hydrides used in applications.

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Section: Resultsmentioning

confidence: 95%

Structural Phase Transitions in Niobium Hydrogen Thin Films: Mechanical Stress, Phase Equilibria and Critical Temperatures

et al. 2019

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“…All films stay adhered to the substrate. 86 b) Detachment pattern observed by confocal microscopy on a Nb film (200 nm) on Sapphire substrate, with a cap and a bottom layer of Pd. The greenish regions (buckles) are detached from the substrate and lifted by about 1.5 μm above the base level (blue color).…”

Section: Coatings: Mechanical Stress Effectsmentioning

confidence: 99%

Hydrogen Interactions with Defects in Materials

Pundt,

Wagner

2024

Chemie Ingenieur Technik

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This manuscript summarizes basic properties of hydrogen in materials, mainly metals, and resulting consequences for the materials properties, including recent developments. It emphasises to introduce into the field of hydrogen in metals in a focused manner. It addresses hydrogen solution in materials, hydride formation, hydrogen diffusion and permeation and the interaction of hydrogen with defects. The influence of hydrogen on the defect energies and consequences for the metal behaviour are addressed. Further, the influence of constraint conditions on the system properties is shortly discussed.

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“…However, this does not mean that the Pd capping layers do not catalyze hydrogen, if they contain iron. Klose et al prepared Pd capping layers in the same sputter system utilized for this work, working at similar iron contents [128]. They were still able to load thin niobium films under the palladium-iron capping layer verifying that hydrogen is still dissociated by the palladium-iron capping layer.…”

Section: Challenges In Step 1) Surface Dissociation Of Hydrogenmentioning

confidence: 78%

Hydrogen diffusion and hydride formation in grain boundary rich magnesium

Hamm¹

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Influence of steel on the mechanical stress development during hydrogen-loading of ultrathin Nb-films

Cited by 5 publications

References 28 publications

Structural Phase Transitions in Niobium Hydrogen Thin Films: Mechanical Stress, Phase Equilibria and Critical Temperatures

Structural Phase Transitions in Niobium Hydrogen Thin Films: Mechanical Stress, Phase Equilibria and Critical Temperatures

Hydrogen Interactions with Defects in Materials

Hydrogen diffusion and hydride formation in grain boundary rich magnesium

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