Sydney team directly observes hydrogen between metal atoms
University of Sydney researchers have directly observed hydrogen occupying spaces between atoms in metal alloys, a state that had been difficult to detect. In a Nature study, they used cryogenic atom probe tomography with deuterium, alongside microscopy and calculations; the results show that alloy composition and atomic arrangement influence where hydrogen accumulates.
Bottom line — The team’s next step is to test how hydrogen in metals affects deformation under stress.
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The finding concerns interstitial hydrogen: atoms dissolved within a metal’s crystal structure, rather than trapped at defects or bound in hydrides.
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The researchers used deuterium, a heavier form of hydrogen, to distinguish the experimental signal from background hydrogen and limit losses during preparation.
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In the alloys tested, deuterium gathered more in nickel-aluminium-titanium precipitates than in the surrounding matrix.
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Tests and calculations indicated that the observed deuterium was predominantly in lattice sites, though the researchers say a minor contribution from undetected defects cannot be ruled out.
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The study established a method for observing hydrogen in solid solution; it does not demonstrate that the tested alloys are already safer for hydrogen storage or transport.
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The research team says it is now investigating how hydrogen affects ultra-high-strength steels under stress.
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