Observation of hydrogen trapping at dislocations, grain boundaries, and precipitates

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Science  10 Jan 2020:
Vol. 367, Issue 6474, pp. 171-175
DOI: 10.1126/science.aaz0122

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An anti-embrittlement roadmap

Hydrogen is important for energy applications such as fuel cells but tends to diffuse into materials and make them more susceptible to fracture. Chen et al. tackled the challenge of identifying the exact location of hydrogen atoms in two common steels. The light weight and high mobility of hydrogen creates serious problems with conventional techniques. The authors used cryo-transfer atom probe tomography to show that hydrogen is pinned to various interfaces in the steels. This direct look into hydrogen trapping should help with the development of materials that are more resistant to hydrogen embrittlement.

Science, this issue p. 171


Hydrogen embrittlement of high-strength steel is an obstacle for using these steels in sustainable energy production. Hydrogen embrittlement involves hydrogen-defect interactions at multiple-length scales. However, the challenge of measuring the precise location of hydrogen atoms limits our understanding. Thermal desorption spectroscopy can identify hydrogen retention or trapping, but data cannot be easily linked to the relative contributions of different microstructural features. We used cryo-transfer atom probe tomography to observe hydrogen at specific microstructural features in steels. Direct observation of hydrogen at carbon-rich dislocations and grain boundaries provides validation for embrittlement models. Hydrogen observed at an incoherent interface between niobium carbides and the surrounding steel provides direct evidence that these incoherent boundaries can act as trapping sites. This information is vital for designing embrittlement-resistant steels.

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