Hydrogen is a key enabler of carbon-neutral energy systems, with applications in transport, power, and renewable energy storage. However, its widespread use is hindered by hydrogen embrittlement (HE)—the degradation of metal properties due to hydrogen ingress. This leads to reduced ductility and early failure of components. Despite its importance, the atomic-scale mechanisms of HE remain poorly understood. The core challenge is the lack of direct evidence of how hydrogen interacts with crystal defects such as dislocations, vacancies, and grain boundaries. Atom probe tomography (APT) is capable of detecting hydrogen at atomic resolution, but conventional instruments suffer from background contamination due to hydrogen outgassing from stainless-steel chambers. Electrochemical hydrogen charging further introduces artefacts, and studies often rely on deuterium labelling, which adds complexity and uncertainty.
The HydMet project addressed these issues by developing a complete platform for direct, reliable hydrogen imaging in metals. The project combined materials science and instrumentation across three objectives:
- Investigate hydrogen trapping at defects using APT and cryogenic transfer techniques.
- Correlate hydrogen with mechanical degradation in crack tips and deformed zones.
- Develop hydrogen-optimized instrumentation and protocols for real-world materials.
The key innovation was a titanium-based APT instrument with ultra-low hydrogen background. This design, paired with cryopumping and getter pumps, reduced background hydrogen by over two orders of magnitude—allowing, for the first time, direct detection of natural hydrogen (¹H) without isotopic substitution. To enable realistic hydrogen exposure, the team developed miniaturized gas-charging devices and a high-pressure setup operating up to 1000 bar and 300 °C. These systems, together with cryogenic specimen handling, enabled controlled hydrogen charging under service-relevant conditions.
HydMet also delivered open-source software: a MATLAB toolbox for FAIR-compliant APT data storage and analysis using HDF5 format. A novel reflectron calibration method was also introduced, improving 3D reconstruction accuracy in APT.
Unexpectedly, the project led to the development of a carbon-stabilized, Ni-free austenitic steel with strong resistance to hydrogen embrittlement. This material offers a cost-effective alternative to traditional Ni-rich steels and is currently under patent.
By the project’s conclusion, the full hydrogen analysis toolchain was operational. First results on Pd, Al, and Ni-superalloys show hydrogen segregation to key defects. Publications are underway, and the methods are now applied in DFG and industrial projects. A new collaborative research centre is in planning.
