Dr. Frank Bergner
Head Materials Characterization
Phone: +49 351 260 - 3186
Fax: 13186, 2205

Materials Characterization

Skizze: Beanspruchung von Reaktorwerkstoffen (deutsch)Materials of components in service can be damaged due to the combined effects of temperature, stress, corrosive media and irradiation, that means, they grow old. A particular phenomenon of this kind is the embrittlement of reactor pressure vessel steels induced by the fission neutrons. The embrittlement manifests itself in the increase of the brittle-ductile transition temperature and in the reduction of the work to fracture. The atomistic mechanisms, which are based on irradiation-induced microstructural changes on the nm-scale, are not yet fully understood.

Generation-IV fission reactors, transmutation facilities and fusion reactors are challenges for the development of new materials. The simulation of neutron-induced damage by means of ion irradiation allows to shorten development cycles and to avoid radiation exposure. The group is collaborating with the Fraunhofer Institute IFAM Dresden to develop new oxide dispersion strengthened (ODS) steels. The damage introduced by ion irradiation of high-Cr steels and ODS steels is in the centre of interest.

Research projects

2015-2018 Safe long term operation of light water reactors based on improved understanding of radiation effects in nuclear structural materials(SOTERIA, EU-FP7 collaborative project)
Grant Agreement No. 661913
2013-2017 Materials’ Innovations for a Safe and Sustainable nuclear in Europe (MatISSE, EU-FP7 collaborative project)
Grant Agreement No. 604862
2011-2014 Materials Testing and Rules (MATTER, EU-FP7 collaborative project)
Grant Agreement No. 269706
2010-2013 Long-term aging effects in RPV steels (national project, GRS/BMWi)
Grant Agreement No. GRS 150 1393
2010-2014 Treatment of long term irradiation embrittlement effects in RPV safety assessment (LONGLIFE, EU-FP7 collaborative project)
Grant Agreement No. 249360
2009-2013 Prediction of the effects of radiation for reactor pressure vessel and in-core materials using multi-scale modelling - 60 years foreseen plant lifetime (PERFORM 60, EU-FP7 collaborative project)
Grant Agreement No. 232612
2008-2013 Generation IV and transmutation materials (GETMAT, EU-FP7 collaborative project)
Grant Agreement No. 212175

Experimental methods

Small-angle neutron scattering (SANS)

KleinwinkelstreuungNanodisperse chemical, structural and magnetic inhomogeneities scatter neutrons (n) or X-rays (X) at small angles. Information on nature, size, number and chemical composition of the inhomogeneities can be obtained from the angular dependence of the intensity of the scattered neutrons. The SANS experiments are performed at the Helmholtz-Zentrum Berlin, the neutron source FRM II at Munich, the Institute Laue-Langevin (ILL) at Grenoble, the Laboratoire Leon Brillouin at Saclay and at KFKI Budapest.

Transmission electron microscopy (TEM)

TEM micrograph of an ODS-Fe9%Cr sampleIrradiation-induced defects such as dislocation loops can be observed by TEM at nm-resolution. With respect to radiation damage, TEM and SANS represent complementary techniques. The application of TEM is also important for the characterization of size, concentration and composition of ODS particles.

Positron annihilation spectroscopy (PAS)

Positrons are self-searching, defect-specific probes for open-volume type defects of sub-nm size and in this respect supplementary to SANS, TEM and Atom probe.  PAS experiments are performed in collaboration at the Institute of Radiation Physics.

Depth-sensing nanoindentation in combination with atom force microscopy (AFM)

AFM-Aufnahme des Eindrucks einer Berkovich Spitze in StahlWährend Neutronen tief in den Werkstoff eindringen und das gesamte Volumen schädigen, bleiben Ionen in einer µm-tiefen Oberflächenschicht stecken. Die geschädigten Volumina sind für die Schädigungscharakterisierung mit SANS und die bruchmechanische Werkstoffprüfung zu gering, es werden alternative Untersuchungsverfahren benötigt. Hier bieten sich neben TEM speziell die tiefenaufgelöste PAS und die registrierende Nanohärte an, letztere in Kombination mit der Atomkraftmikroskopie, welche die sub-µm großen Details der Härteeindrücke abzubilden vermag.

Finished diploma and PhD theses:

  • C. Heintze (2012), Einfluss der Bestrahlung mit energiereichen Teilchen auf die Härte von Fe-Cr-Legierungen, Dissertation, TU Dresden, Fakultät für Maschinenwesen.
  • P. Franke (2009), Herstellung und Charakterisierung von dispersionsverfestigten Fe-Cr-Modelllegierungen für kerntechnische Werkstoffentwicklungen, Diplomarbeit, TU BA Freiberg.
  • C. Recknagel (2008), Registrierende Nanohärtemessung und begleitende Atomkraftmikroskopie an unbestrahlten und ionenbestrahlten Stählen, Diplomarbeit, TU Dresden, Fakultät für Maschinenwesen.
  • C. Heintze (2006), Anforderungsprofil und Eigenschaftsspektrum ausgewählter Stähle für Kernenergieanlagen, Diplomarbeit, TU Dresden, Fakultät für Maschinenwesen.
  • A. Ulbricht (2006), Untersuchungen an neutronenbestrahlten Reaktordruckbehälterstählen mit Neutronen-Kleinwinkelstreuung, Dissertation, TU BA Freiberg, Wissenschaftlich-Technische Berichte, Forschungszentrum Rossendorf, FZR-453.

Selected publications:

  • I. Hilger, M. Tegel, M.J. Gorley, P.S. Grant, T. Weißgärber, B. Kieback (2014), The structural changes of Y2O3 in ferritic ODS alloys during milling, J. Nucl. Mater. 447, 242-247.
  • C. Heintze, F. Bergner, M. Hernández-Mayoral (2011), Ion-irradiation-induced damage in Fe-Cr alloys characterized by nanoindentation, J. Nucl. Mater. 417, 980-983.
  • F. Bergner, A. Ulbricht, C. Heintze (2009), Estimation of the solubility limit of Cr in Fe at 300°C from small angle neutron scattering in neutron-irradiated Fe-Cr alloys, Scripta Materialia 61, 1060-1063.
  • F. Bergner, A. Ulbricht, H.-W. Viehrig (2009), Acceleration of irradiation hardening of low-copper reactor pressure vessel steel observed by means of SANS and tensile testing, Phil. Mag. Lett. 89, 795-805.
  • C. Heintze, C. Recknagel, F. Bergner, M. Hernandez-Mayoral, A. Kolitsch (2009), Ion-irradiation-induced damage of steels characterized by means of nanoindentation, Nucl. Instr. and Meth. in Phys. Res. B 267, 1505-1508.
  • F. Bergner, A. Ulbricht, H. Hein, M. Kammel (2008), Flux dependence of cluster formation in neutron-irradiated weld material, J. Phys.: Condens. Matter 20, 104262 (6pp).
  • A. Ulbricht, F. Bergner, J. Böhmert, M. Valo, M.-H. Mathon, A. Heinemann (2007), SANS response of VVER440-type weld material after neutron irradiation, post-irradiation annealing and reirradiation, Philosophical Magazine 87, 1855-1870.


Dr. Frank Bergner
Head Materials Characterization
Phone: +49 351 260 - 3186
Fax: 13186, 2205