Isolation, observation and quantification of mechanisms responsible for hydrogen embrittlement by TRITIum based microMEchanics

Project Information

TRITIME

Grant agreement ID: 101043969

DOI

10.3030/101043969

EC signature date 11 May 2022

Start date 1 November 2022

End date 31 October 2027

Funded under

• European Research Council (ERC)

Total cost

€ 1 994 136,00

EU contribution

€ 1 994 136,00

Coordinated by

KARLSRUHER INSTITUT FUER TECHNOLOGIE
Germany

Periodic Reporting for period 1 - TRITIME (Isolation, observation and quantification of mechanisms responsible for hydrogen embrittlement by TRITIum based microMEchanics)

Reporting period: 2022-11-01 to 2025-04-30

Summary of the context and overall objectives of the project

The TRITIME project is dedicated to developing a new toolbox for understanding hydrogen embrittlement, utilizing tritium as an isotope. This approach enables the distinction between chemical effects – determined by the electronic structure of hydrogen and its isotopes – and mobility aspects, which are influenced by the mass of the hydrogen isotope. The overarching goal is to achieve a mechanistic understanding of hydrogen embrittlement.
The first major challenge lies in charging metallic samples with tritium, a process that necessitates stringent safety measures. TRITIME employs two methods for this: charging with a 500 ppm tritium/hydrogen mix in the Fusion Materials Laboratory (FML) at the Karlsruhe Institute of Technology, and pure tritium charging in the Tritium Laboratory Karlsruhe (TLK).
The second challenge involves the development of a new multi-channel plate (MCP) detector. This detector is designed to observe the radioactive decay of tritium with high spatial resolution (<10 µm) and represents a central focus of the project.
Finally, benchmark experiments using Atom Probe Tomography (APT) and Secondary Ion Mass Spectrometry (SIMS) constitute the final step within the first reporting period. These experiments are essential for calibrating the MCP detector once it is operational.
With these advancements, the TRITIME toolbox will be fully equipped to investigate the primary hydrogen embrittlement mechanisms: Hydrogen-Enhanced Decohesion (HEDE), Hydrogen-Enhanced Localized Plasticity (HELP), and their interactions.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The works performed during the reporting period include several key activities essential to the success of the TRITIME project. First, protocols for tritium charging were established, ensuring a reliable and efficient process for introducing tritium into metallic samples. Additionally, protocols were developed to facilitate the safe exchange of tritium between the participating laboratories, strictly adhering to radiation protection legislation.
In this reporting period, the project also focused on the design and procurement of specialized equipment, including a chamber for tritium testing and a multi-channel plate (MCP) detector system. To support experimental efforts, model materials for TRITIME were identified and purchased, forming the basis for subsequent testing and analysis.
A significant achievement was the establishment of a correlative workflow that integrates tritium charging with chemical analysis techniques, ensuring high spatial resolution. This workflow incorporates SIMS and APT. Benchmarking experiments were successfully conducted using these techniques, laying the groundwork for calibrating the MCP detector and advancing the project's objectives.

A major milestone during this first 24-month research period is that, we have successfully established the correlative Tritium charging – Thermal Desorption Spectroscopy (TDS) measurement –APT quantification as the benchmarking testing workflow. To the best of our knowledge, this has not been achieved before elsewhere.
A new nanomechanical setup was installed at the FML
Based on this workflow and with the new in situ nanomechanical testing setup successfully installed in the Fusion Materials Laboratory, the working protocol of Tritium charging – Microcantilever bending (WP2) & Micropillar compression (WP3) – APT quantification will be readily established in early 2025.
With the MCP detector being assembled and ready to test for Tritium detection in Jan. 2025, we will correlate the MCP detector and the APT results, to pave the road for Objectives (ii-v) in DoA.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

During the starting phase of TRITIME, the team has given several talks and published a paper in Scripta Materialia. These includes:

Talks:
- "Probing hydrogen with high spatial resolution: a new correlative deformation/hydrogen sensing technique for hydrogen embrittlement study", presented by Maria Vrellou, Xufei Fang, Hans-Christian Schneider, Alexander Welle, Astrid Pundt, Christoph Kirchlechner, DPG-Conference, March 2024
- "Measurement of Tritium with a novel detector system", presented by Joris Müller, Xufei Fang, Christoph Kirchlechner, DPG-Conference, March 2024
- "Probing hydrogen with high spatial resolution: a new correlative deformation/hydrogen sensing technique for hydrogen embrittlement studies", presented by Joris Müller, Maria Vrellou, Rolf Rolli, Hans-Christian Schneider, Astrid Pundt, Xufei Fang, Christoph Kirchlechner, DGM FA “Wasserstoffeffekte in Materialien”

Besides, for the first time, a drastic softening of Pd nanoparticles after hydrogen cycling caused by hydrogen induced dislocations was observed. This softening effect was correlated with the high density of glissile dislocations observed in the H-cycled particles. This work demonstrates that the nanomechanical behaviour of hydride-forming metals such as Pd can be manipulated by hydrogen cycling. This study also has important indications on nanoparticle catalytic efficiencies considering the pivotal role played by Pd as catalysts for hydrogenolysis and for hydrogen economy. Reference: Jonathan Zimmerman, Maria Vrellou, Stefan Wagner, Astrid Pundt, Christoph Kirchlechner, Eugen Rabkin, Drastic softening of Pd nanoparticles induced by hydrogen cycling, Scripta Materialia, 253, 116304, 2024

Finally as part of the material selection process we tackled a fundamental question regarding hydrogen-dislocation interactions in perovskite oxides, which is gaining increasing research interest because of their potential in boosting the availability of proton-conducting electrolytes and mixed proton–electron conductors in fuel cells and electrolyzers (predominantly made of oxides). In addition, proton mediation of electronic properties has also inspired interest for electrochemically controlled energy-efficient neuromorphic computing in functional/electronic oxides. Our findings suggest that line defects such as dislocations can drastically increase the hydrogen diffusion, which has important implications for hydrogen tuning in perovskite oxides provided the dislocations can be tuned in the first place, which has been achieved in recent years. The paper is in preparation, and planned to be submitted soon. Reference: Xufei Fang, Lars Dörrer, Svetlana Korneychuk, Astrid Pundt,Harald Schmidt, Christoph Kirchlechner, under preparation, Hydrogen response to dislocations in perovskite oxide, under preparation, 2024


Both aforementioned articles are based on fundamental reseach being unplanned and unforeseen in the first place, but these two preliminary works have clearly pushed forward our understanding of hydrogen-defects interactions in critical material systems related to hydrogen economy, which aligns perfectly with the overarching goal of TRITIME. They are simple material systems to test the work flow established in TRITIME and are therefore listed here.