Hydrogen behaviour in solid materials

Hydrogen is the lightest element in the periodic table and, as hydrogen-based technology rapidly advances, in particular for powering car engines, the need for better fundamental understanding of materials-hydrogen interactions is rising. For instance, mobile H is crucial to the integrity of metals in nuclear power plants. Similarly, hydrogen embrittlement is a well-documented failure mechanism encountered in many energy applications and across the metallurgical industry.

Hydrogen is often present in metals that become loaded during high-temperature processing, when hydrogen from the environment can be absorbed by the metal. At somewhat lower temperatures, H, in atomic or molecular form, can generally diffuse rapidly compared with other elements, but can also become trapped at defects and interfaces. In some situations such trapping leads to gas bubble evolution within the materials, and such bubbles can act as nuclei for cracks.

Because hydrogen has such a low atomic mass and atomic number, it is inherently difficult to observe, measure and map within a microstructure.  This means in turn that the underlying mechanisms that cause hydrogen trapping and embrittlement are still open to discussion and study.

We have selected recent articles related to the behavior of H in a range of metals and metallic alloys – steel, Ni, Ti, Zr, Pd – all published in both Acta Materialia and Scripta Materialia. These articles have been made available for free to read for the next six months: 

• Influence of trap connectivity on H diffusion: Vacancy trapping
• Mechanisms of hydrogen-enhanced localized plasticity: An atomistic study using α-Fe as a model system
• Effects of multiple hydrogen absorption/desorption cycles on the mechanical properties of the alloy system palladium/silver (wt% = 10–25)
• Dislocation/hydrogen interaction mechanisms in hydride nanocrystalline palladium films
• Hydrogen diffusion in ultrafine-grained palladium: Roles of dislocations and grain boundaries
• Hydrogen and vacancy clustering in zirconium
• Hydrogen diffusivities as a measure of relative dislocation densities in palladium and increase of the density by plastic deformation in the presence of dissolved hydrogen
• Multiscale modeling of hydrogen enhanced homogeneous dislocation nucleation
• Multi-scale and spatially resolved hydrogen mapping in a Ni–Nb model alloy reveals the role of the δ phase in hydrogen embrittlement of alloy 718
• Hydrogen assisted crack initiation and propagation in a nickel-based superalloy

We hope you enjoy reading these articles.

Prof. Chris Schuh (Coordinating Editor)

Dr Baptiste Gault (Associate Editor)

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