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Ion irradiation induced changes in Fe-Cr alloys investigated by synchrotron techniques

Applicant Borca Camelia
Number 144538
Funding scheme Project funding (Div. I-III)
Research institution Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Material Sciences
Start/End 01.10.2012 - 31.07.2013
Approved amount 50'635.00
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All Disciplines (2)

Discipline
Material Sciences
Condensed Matter Physics

Keywords (5)

X-ray Magnetic Circular Dichroism; ion irradiation; X-ray Absorption; FeCr alloys; X-ray Diffraction

Lay Summary (English)

Lead
The next generation nuclear reactors must be safer and more efficient in terms of power production. In addition to the elevated temperatures they will be operating at, they will be generating highly energetic particles as well as use aggresive coolants. The safety of these advanced systems will depend on the capability of the chosen structural materials to withstand these harsh operating conditions.
Lay summary

Ferritic-martensitic steels are considered as one of the most promising candidates for structural materials to be used under extreme conditions of temperature and irradiation fluencies. Understanding of the evolution of mechanical properties under these extreme operation conditions is of primary importance.

The aim of the work is to advance the knowledge regarding the nanostructure (from the magnetic properties perspective) and its evolution in FeCr alloys under ion irradiation, taking into account that different variables will affect the microstructure and, hence, the behavior of materials under irradiation. The behavior of the Fe-Cr system under irradiation has certain peculiarities, the natures of which are not quite clear yet. The strong hardening and embrittlement inherent to these materials in a radiation field may cause difficulties under extreme conditions of temperature and irradiation fluencies.

The main characterisation techniques applied will be: XMCD (X-ray Magnetic Circular Dichroism), XRD (X-ray diffraction) and EXAFS (Extended X-ray Absorption Fine Structure) spectroscopy. Complementary techniques such as TEM (Transmission Electron Microscopy) and PEEM (Photoemission Electron Microscopy) will be used to investigate the ion-irradiated surface layer.

The combination of proposed experiments on the ion-irradiated Fe-Cr binary alloy matrix at the nano-scale will allow proper investigations of the influence of magnetism on defect mobility, its effect on precipitation and segregation, and its anisotropic behaviour due to the ferromagnetic/ antiferromagnetic nature of the Fe-Cr alloy matrix which have important implications for the prediction of mechanical properties of Fe-Cr alloys. These investigations will furthermore provide basic information on the material’s plasticity, where assessing clustering and precipitation is necessary due to the hindering nature of precipitates which can pin dislocations and lead to a precipitation hardening effect. Knowledge of the material’s mechanical properties from a fundamental level will lay the foundation of a modeling program which can be predictive, and will greatly impact the scientific community in its study of traditionally experimentally tackled problems.

Direct link to Lay Summary Last update: 12.09.2013

Responsible applicant and co-applicants

Employees

Name Institute

Collaboration

Group / person Country
Types of collaboration
Hiroshima Synchrotron Radiation Center Japan (Asia)
- Research Infrastructure
Interdisciplinary Centre for Electron Microscopy Switzerland (Europe)
- Research Infrastructure

Communication with the public

Communication Title Media Place Year
Media relations: print media, online media Testing materials for next-generation nuclear reactors International 15.08.2013

Associated projects

Number Title Start Funding scheme
121709 Understanding the role of nanomagnetism in the Fe-Cr alloy system using synergistic X-ray Magnetic Circular Dichroism experiments and first principle ab initio calculations 01.07.2009 Project funding (Div. I-III)

Abstract

High Cr (9-14%Cr) ferritic/martensitic steels are considered as one of the most promising candidates for structural materials for Generation IV and fusion reactors. Therefore, the understanding of the evolution of properties under operation conditions is of primary importance. The aim of the work is to advance the knowledge regarding the nanostructure (from the magnetic properties perspective) and its evolution in FeCr alloys under ion irradiation, taking into account that different variables will affect the microstructure and, hence, the behaviour of materials under irradiation.The materials considered for this study are four commercial purity FeCr binary alloys with varying Cr content, as well as a set of four ultra-high purity FeCr alloys, specially designed for model validation. The same set of materials will be ion irradiated at different temperatures and doses at the Ion Beam Centre at HZDR (Dresden-Rossendorf, Germany). The irradiated layer will be restricted to a surface layer of 1.5 microns thick. The main characterisation techniques applied will be: XMCD (X-ray Magnetic Circular Dichroism), XRD (X-ray diffraction) and EXAFS (Extended X-ray Absorption Fine Structure) spectroscopy. Complementary techniques such as TEM (Transmission Electron Microscopy) and PEEM (Photoemission Electron Microscopy) will be used to investigate the damaged surface layer. The complementarily of the techniques and the combination of their results will provide a more comprehensive picture of the nanostructure induced by irradiation as each of them is sensitive to different aspects of the irradiation damage. The whole set of experimental conditions, allows information to be obtained on the influence of the different variables involved, namely, Cr content, dose and irradiation temperature and, consequently, about fundamental processes occurring under ion irradiation.
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