We investigate the behavior of materials exposed to energetic particle irradiation. The work contributes to the program NUSAFE (Nuclear Waste Management, Safety and Radiation Research) of the Helmholtz Association.
Neutron irradiation provokes the formation and long-term evolution of nm-scale defects such as dislocation loops and solute atom clusters. These defects give rise to hardening accompanied by a reduced fracture resistance of reactor pressure vessel steels of running nuclear power plants. Materials for advanced reactor concepts will be exposed to higher operation temperatures and higher neutron doses. The overall objectives of our research are to identify the mechanisms of irradiation-induced damage in structural materials and to assess the resulting changes of the mechanical properties.
We work on two main directions:
- In the case of running nuclear power plants, the work is focused on long-term irradiation effects in reactor pressure vessel steels.
- Our work in the field of advanced reactor concepts is dedicated to ferritic/martensitic Cr-steels, oxide dispersion strengthened (ODS) steels and the emerging class of high-entropy alloys.
The new insight substantially contributes to the scientific background for the safety assessment of nuclear reactors. The work is embedded in the Euratom projects SOTERIA, MATISSE and M4F. A close cooperation with the Fundamentals and Simulation Group provides additional insight via atomistic simulation.
- Mechanical testing of irradiated materials
- Characterization at the nm length scale
- Ion irradiation to emulate neutron irradiation effects
Microstructure-informed prediction of hardening in ion-irradiated reactor pressure vessel steels
Ion irradiation combined with nanoindentation is a promising tool to study irradiation-induced hardening of nuclear materials including reactor pressure vessel (RPV) steels. For RPV steels, the major sources of hardening are nm-sized irradiation-induced dislocation loops and solute atom clusters, both representing barriers for dislocation glide. The dispersed barrier hardening (DBH) model provides a link between the irradiation-induced nanofeatures and hardening. However, a number of details of the DBH model still require consideration. These include the role of the unirradiated microstructure, the proper treatment of the indentation size effect (ISE), and the appropriate superposition rule of individual hardening contributions. In the present study, two well characterized RPV steels, each ion-irradiated up to two different levels of displacement damage, were investigated. Dislocation loops and solute atom clusters were characterized by transmission electron microscopy and atom probe tomography, respectively. Nanoindentation with a Berkovich indenter was used to measure indentation hardness as a function of the contact depth. In the present paper, the measured hardening profiles are compared with predictions based on different DBH models. Conclusions about the appropriate superposition rule and the consideration of the ISE (in terms of geometrically necessary dislocations) are drawn.
Keywords: reactor pressure vessel steels; ion irradiation; microstructure characterization; transmission electron microscopy; atom probe tomography; nanoindentation; hardening
- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 38696) publication
Data publication: Microstructure-informed prediction of hardening in …
ROBIS: 38698 HZDR-primary research data are used by this (Id 38696) publication
Online First (2024) DOI: 10.3390/met14030257
|+49 351 260
|Dr. Eberhard Altstadt
|Dr. Cornelia Kaden
|+49 351 260
|Dr. Frank Bergner
|Dr. Jann-Erik Brandenburg
|Dr. Paul Chekhonin
|Dr. Andreas Ulbricht