Periodic Reporting for period 4 - HydMet (Fundamentals of Hydrogen in Structural Metals at the Atomic Scale)
Reporting period: 2023-06-01 to 2024-09-30
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.
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.
The HydMet project investigated the fundamental interactions between hydrogen and crystalline defects in metallic materials at the atomic scale. These interactions are critical to understanding hydrogen embrittlement, a major barrier to deploying hydrogen-based technologies. The project was structured around three work packages (WPs), combining materials science, instrumentation development, and method innovation.
WP1: Hydrogen in the Microstructure aimed to quantify hydrogen (or deuterium) at defects like grain boundaries, dislocations, and vacancies. Initial deuterium experiments on iron alloys using a commercial atom probe revealed issues with artefacts and inconsistent signal retention. This led to the development of cryogenic transfer protocols and evaluation of deuterated sample preparation, though the latter was delayed by COVID-19 supply issues. WP1 provided critical insights that informed the design of improved detection methods.
WP2: Hydrogen-Induced Fracture, originally based on micro-tensile testing, WP2 pivoted to macro-scale tensile tests due to difficulties with in-situ charging at the microscale. These tests revealed a range of hydrogen effects depending on alloy and conditions. While crack-tip imaging via APT was not achieved due to specimen preparation challenges, EBSD and mechanical data are being prepared for publication.
WP3: Hydrogen “In the Wild” produced the project’s most impactful results. The key achievement was the development of a titanium-based atom probe with ultra-low hydrogen background. This allowed, for the first time, the direct detection of natural (¹H) hydrogen without deuterium labelling. The instrument now supports both voltage and laser pulsing and is fully open-source, including control software and hardware documentation. To complement this, gas charging systems were built: two miniaturized setups for up to 10 bar, and a high-pressure facility enabling charging up to 1000 bar and 300°C. These systems are operational and have been used to analyze hydrogen in Pd, Ni-based alloys, and austenitic steels.
Unexpectedly, the project also developed a Ni-free, carbon-stabilized austenitic steel with good hydrogen resistance. This has been published, is under patent application, and is being further developed with industry partners.
Eight publications have resulted, with more in preparation. An open-source MATLAB toolbox for FAIR-compliant APT data handling was released and is already in international use. The team ran a global software school, contributed to conferences, and helped establish hydrogen-focused networks. The project laid the foundation for further DFG and industrial projects and a planned collaborative research centre.
WP1: Hydrogen in the Microstructure aimed to quantify hydrogen (or deuterium) at defects like grain boundaries, dislocations, and vacancies. Initial deuterium experiments on iron alloys using a commercial atom probe revealed issues with artefacts and inconsistent signal retention. This led to the development of cryogenic transfer protocols and evaluation of deuterated sample preparation, though the latter was delayed by COVID-19 supply issues. WP1 provided critical insights that informed the design of improved detection methods.
WP2: Hydrogen-Induced Fracture, originally based on micro-tensile testing, WP2 pivoted to macro-scale tensile tests due to difficulties with in-situ charging at the microscale. These tests revealed a range of hydrogen effects depending on alloy and conditions. While crack-tip imaging via APT was not achieved due to specimen preparation challenges, EBSD and mechanical data are being prepared for publication.
WP3: Hydrogen “In the Wild” produced the project’s most impactful results. The key achievement was the development of a titanium-based atom probe with ultra-low hydrogen background. This allowed, for the first time, the direct detection of natural (¹H) hydrogen without deuterium labelling. The instrument now supports both voltage and laser pulsing and is fully open-source, including control software and hardware documentation. To complement this, gas charging systems were built: two miniaturized setups for up to 10 bar, and a high-pressure facility enabling charging up to 1000 bar and 300°C. These systems are operational and have been used to analyze hydrogen in Pd, Ni-based alloys, and austenitic steels.
Unexpectedly, the project also developed a Ni-free, carbon-stabilized austenitic steel with good hydrogen resistance. This has been published, is under patent application, and is being further developed with industry partners.
Eight publications have resulted, with more in preparation. An open-source MATLAB toolbox for FAIR-compliant APT data handling was released and is already in international use. The team ran a global software school, contributed to conferences, and helped establish hydrogen-focused networks. The project laid the foundation for further DFG and industrial projects and a planned collaborative research centre.
The HydMet project has made a major advance in hydrogen-materials research by enabling, for the first time, direct atomic-scale imaging of hydrogen in metals. Previously, hydrogen detection in atom probe tomography (APT) relied on indirect methods—typically deuterium labelling and electrochemical charging in stainless-steel instruments—leading to artefacts, poor reproducibility, and high background contamination.
To overcome these limitations, the project developed a complete end-to-end methodology for quantitative hydrogen analysis. The central breakthrough was the design of a titanium-based atom probe with an ultra-low hydrogen background. This reduced background hydrogen by over two orders of magnitude and enabled detection of natural (¹H) hydrogen. First results have already demonstrated hydrogen segregation to defects in real alloys.
This capability was complemented by the development of gas charging systems, including miniaturized 10 bar/90 °C setups and a high-pressure facility operating up to 1000 bar and 300 °C. Together with cryogenic transfer, these tools allow realistic, reproducible hydrogen charging.
A FAIR-compliant, open-source MATLAB toolbox was also developed for standardized APT data analysis and sharing, replacing closed-source tools and improving reproducibility. It has already been adopted by other labs.
Unexpectedly, the project also produced a Ni-free, carbon-stabilized austenitic steel with high resistance to hydrogen embrittlement—offering a cost-effective, sustainable alternative to Ni-based alloys. A patent application is underway.
By the end of the project, the full toolchain is operational and delivering results. Publications on hydrogen trapping in Pd, Al, and Ni-superalloys, as well as on the titanium atom probe and laser pulsing, are in preparation. The methods are now being applied in DFG and industry-funded projects and form the basis of a planned collaborative research centre.
To overcome these limitations, the project developed a complete end-to-end methodology for quantitative hydrogen analysis. The central breakthrough was the design of a titanium-based atom probe with an ultra-low hydrogen background. This reduced background hydrogen by over two orders of magnitude and enabled detection of natural (¹H) hydrogen. First results have already demonstrated hydrogen segregation to defects in real alloys.
This capability was complemented by the development of gas charging systems, including miniaturized 10 bar/90 °C setups and a high-pressure facility operating up to 1000 bar and 300 °C. Together with cryogenic transfer, these tools allow realistic, reproducible hydrogen charging.
A FAIR-compliant, open-source MATLAB toolbox was also developed for standardized APT data analysis and sharing, replacing closed-source tools and improving reproducibility. It has already been adopted by other labs.
Unexpectedly, the project also produced a Ni-free, carbon-stabilized austenitic steel with high resistance to hydrogen embrittlement—offering a cost-effective, sustainable alternative to Ni-based alloys. A patent application is underway.
By the end of the project, the full toolchain is operational and delivering results. Publications on hydrogen trapping in Pd, Al, and Ni-superalloys, as well as on the titanium atom probe and laser pulsing, are in preparation. The methods are now being applied in DFG and industry-funded projects and form the basis of a planned collaborative research centre.