Structural Materials
The safety of nuclear reactors critically depends on the mechanical behavior of structural materials under harsh environmental conditions (neutron irradiation, high temperatures). In the framework of the program NUSAFE (Nuclear Waste Management, Safety and Radiation Research) of the Helmholtz Association we characterize irradiated reactor materials from the nm-scale to the macro-scale. Our focus:
- Long-term irradiation effects in reactor pressure vessel steels of running and new-build reactors in the context of lifetime extension
- Assessment of the irradiation tolerance of innovative materials for future reactor concepts including nuclear fusion (e.g. ferritic/martensitic Cr-steels, oxide dispersion strengthened (ODS) steels, the emerging class of high-entropy alloys)
The methodical spectrum covers the full functional chain from nm-scale irradiation-induced defects to macroscopic mechanical properties and aims at the identification, better understanding and mitigation of irradiation effects. The new insight substantially contributes to the scientific background for the safety assessment of nuclear reactors. The research relies on a unique infrastructure including the hot cell labs for the investigation of neutron-irradiated materials as well as the HZDR Ion Beam Center for ion irradiation experiments.
Our expertise:
- Mechanical testing of irradiated materials
- Nano-/Microstructure characterization of irradiated materials
- Ion irradiation to emulate neutron irradiation effects
Current projects
- Innovative structural materials for fission and fusion
(INNUMAT, EU, HORIZON-EURATOM, 2022-2026) - European Database for Multiscale Modelling of Radiation Damage
(ENTENTE, EU-H2020-Euratom, 2020-2024) - Fracture mechanics testing of irradiated RPV steels by means of sub-sized specimens
(FRACTESUS, EU-H2020-Euratom, 2020-2024) - Structural Materials research for safe Long Term Operation of LWR NPPs
(STRUMAT-LTO, EU-H2020-Euratom, 2020-2024) - Untersuchungen zum Ausheilverhalten von Reaktordruckbehälterstählen bei niedrigen Temperaturen
(WetAnnealing, BMWI, 2020-2025) - Physical modelling and modelling-oriented experiments for structural materials 2
(IOANIS2, EERA-JPNM Pilote Project, 2023 - 2027, coordinator HZDR) - In-situ experiments for nuclear applications
(INSITEX, EERA-JPNM Pilote Project, 2023 - 2027) - On the use of small punch as high-throughput screening technique to extract mechanical properties of ion irradiated materials
(SHERPA, EERA-JPNM Pilote Project, 2023 - 2027)
Latest Publication
On the solute segregation to grain boundaries in SA508 steel
Klupś, P.; Jenkins, B. M.; Chekhonin, P.; Douglas, J. O.; Carter, M.; Tang, Y. T.; Hyde, J. M.; Riddle, N.; Bagot, P. A. J.; Moody, M. P.
Abstract
Solute segregation to grain boundaries (GBs) within a high-Ni alloy (SA508 Grade 4N) aged at 427 °C
was studied to investigate the role of phosphorus in causing non-hardening embrittlement in these
steels. Electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) were employed
to identify and characterise grain boundaries prior to targeted atom probe tomography (APT) analysis.
Boundaries were classified as prior–austenite grain boundaries (PAGBs) and packet/block (lath) bound-
aries, enabling segregation behaviour to be directly correlated with crystallographic misorientation and
boundary type. Distinct segregation patterns were observed at PAGBs compared to other boundaries,
with strong anti–correlation between P/C and Ni/Mn/Si at PAGB interfaces. In unaged PAGBs, non–
equilibrium segregation driven by vacancy drag promoted Ni enrichment, whereas W–shaped Ni con-
centration profiles in aged PAGBs indicate P–driven reverse vacancy flow. In contrast, solute enrichment
at lath boundaries was found to depend strongly on misorientation angle. These results highlight the crit-
ical importance of controlling the 5-DoF when assessing segregation–driven embrittlement mechanisms
in bainitic/martensitic steels. They also emphasise the potential of grain boundary engineering as a design
strategy for improving resistance to embrittlement in nuclear and other demanding applications.
-
Journal of Materials Research and Technology 270(2026), 163-173
DOI: 10.1016/j.jmst.2026.01.027
Permalink: https://www.hzdr.de/publications/Publ-42987
Team
Head | |||||
| Name | Bld./Office | +49 351 260 | |||
|---|---|---|---|---|---|
| Dr. Eberhard Altstadt | e.altstadt hzdr.de | ||||
| Dr. Cornelia Kaden | 801/P102 | 3431 | c.kaden@hzdr.de, c.heintzehzdr.de | ||
Employees | |||||
| Name | Bld./Office | +49 351 260 | |||
| Dr. Paul Chekhonin | 801/P146 | 2149 | p.chekhoninhzdr.de | ||
| Vanessa Dykas | 801/P148 | 3363 | v.dykashzdr.de | ||
| Mario Houska | 801/P148 | 2242 | m.houskahzdr.de | ||
| Jens Pietzsch | 801/P032 | 2814 3550 | jens.pietzschhzdr.de | ||
| Dr. Andreas Ulbricht | 801/P146 | 3155 | |||
| Wolfgang Webersinke | 801/P148 | 2766 2129 | w.webersinkehzdr.de | ||
| Tilo Welz | 801/P032 | 2814 | t.welzhzdr.de | ||
Latest publication
On the solute segregation to grain boundaries in SA508 steel
Klupś, P.; Jenkins, B. M.; Chekhonin, P.; Douglas, J. O.; Carter, M.; Tang, Y. T.; Hyde, J. M.; Riddle, N.; Bagot, P. A. J.; Moody, M. P.
Abstract
Solute segregation to grain boundaries (GBs) within a high-Ni alloy (SA508 Grade 4N) aged at 427 °C
was studied to investigate the role of phosphorus in causing non-hardening embrittlement in these
steels. Electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) were employed
to identify and characterise grain boundaries prior to targeted atom probe tomography (APT) analysis.
Boundaries were classified as prior–austenite grain boundaries (PAGBs) and packet/block (lath) bound-
aries, enabling segregation behaviour to be directly correlated with crystallographic misorientation and
boundary type. Distinct segregation patterns were observed at PAGBs compared to other boundaries,
with strong anti–correlation between P/C and Ni/Mn/Si at PAGB interfaces. In unaged PAGBs, non–
equilibrium segregation driven by vacancy drag promoted Ni enrichment, whereas W–shaped Ni con-
centration profiles in aged PAGBs indicate P–driven reverse vacancy flow. In contrast, solute enrichment
at lath boundaries was found to depend strongly on misorientation angle. These results highlight the crit-
ical importance of controlling the 5-DoF when assessing segregation–driven embrittlement mechanisms
in bainitic/martensitic steels. They also emphasise the potential of grain boundary engineering as a design
strategy for improving resistance to embrittlement in nuclear and other demanding applications.
-
Journal of Materials Research and Technology 270(2026), 163-173
DOI: 10.1016/j.jmst.2026.01.027
Permalink: https://www.hzdr.de/publications/Publ-42987
Team
Head | |||||
| Name | Bld./Office | +49 351 260 | |||
|---|---|---|---|---|---|
| Dr. Eberhard Altstadt | e.altstadthzdr.de | ||||
| Dr. Cornelia Kaden | 801/P102 | 3431 | c.kaden@hzdr.de, c.heintzehzdr.de | ||
Employees | |||||
| Name | Bld./Office | +49 351 260 | |||
| Dr. Paul Chekhonin | 801/P146 | 2149 | p.chekhoninhzdr.de | ||
| Vanessa Dykas | 801/P148 | 3363 | v.dykashzdr.de | ||
| Mario Houska | 801/P148 | 2242 | m.houskahzdr.de | ||
| Jens Pietzsch | 801/P032 | 2814 3550 | jens.pietzschhzdr.de | ||
| Dr. Andreas Ulbricht | 801/P146 | 3155 | |||
| Wolfgang Webersinke | 801/P148 | 2766 2129 | w.webersinkehzdr.de | ||
| Tilo Welz | 801/P032 | 2814 | t.welzhzdr.de | ||
