Skip to main content

Seeing hydrogen in matter

Periodic Reporting for period 2 - SHINE (Seeing hydrogen in matter)

Reporting period: 2019-08-01 to 2021-01-31

The main aim of SHINE is to push the boundaries of quantitative analysis of hydrogen in materials in three-dimensions and at near-atomic resolution using atom probe tomography. The materials of interest find applications in the scope of a ‘low-carbon-emission economy’ either for hydrogen storage, or for light-weight transportation where hydrogen embrittlement is a crucial limiting factor.

The project officially started in Feb 2018. SHINE builds on the expertise and world-unique infrastructure in the Atom Probe group at MPIE. SHINE uses the Project Laplace established at MPIE in 2017, and is still being developed.
Following on preliminary results on H in Ti published in Acta Materialia, we used the uncontrolled ingress of H during specimen preparation to load samples of Ti-Mo alloys with different microstructures, as shown in this letter in Scripta Materialia, highlighting the influence on the initial phase composition on the H-behaviour. Crucially, we demonstrated that H-introduction during specimen preparation could be avoided by performing the final steps of the specimen preparation at cryogenic temperatures, as shown in this article in Nature Communications, borrowing techniques from biologists. In parallel, we started studying stable hydrides and deuterides of Zr, in a collaboration with Dr Ben Britton from Imperial College London, and we revealed interesting processes taking place between the hydride and the metallic matrix, namely a redistribution of Sn and the presence of an interfacial region with a different crystal structure and composition – published in Scripta Materialia. We went on to perform a systematic study of how well hydrogen or deuterium could be quantified in Zr-based hydrides and Ti-hydrides.
We have made significant progress in the detection of H and the clean preparation of specimens for H-quantification and their transfer into the instrument. As expected, some unforeseen hurdles came our way, but we have understood many of the limitations and have developed paths to circumvent those issues. Amongst the key issues is the uncontrolled introduction of H during the preparation of specimens, during conventional electrochemical polishing or FIBbing. We showed that cryo-enabled techniques are necessary, which limits the throughput.
Experiments are still not routine, but are much better established. We now work on a range of different materials.

until the end of the project, we will focus on feeding information to our theory collaborators, to try and better understand mechanisms underpinning H-embrittlement. Two articles are underway.

With regards to materials relevant to the hydrogen economy, we have made good progress on the front of analysing nanoscale materials by APT, and enabling new, facile approaches to get these complex samples into an analysable shape. We are in preparation of several articles on this front too. Samples obtained during H-cycling will be analysed soon.
Figure from our artciel showing the detection of deuterium segregated at an in a high-strength steel