APT study of radiation-induced segregation ferritic/martensitic steels after irradiation with high-energy protons and spallation neutrons

Yong Dai

Laboratory for Nuclear Materials, Paul Scherrer Institute, Switzerland

Abstract:

Ferritic/martensitic (FM) and ODS steels have been extensively studied in various fission and fusion material R&D projects around the world. These steels are also candidate structural materials for high power spallation targets. Over the past two decades, a large number FM and ODS steels have been irradiated in a wide range of doses and temperatures in the targets of the Swiss Spallation Neutron Source (SINQ), with spectra of mixed high-energy protons and spallation neutrons. A large body of mechanical testing and transmission electron microscopy have been carried out. The results show that the mechanical properties and microstructures of SINQ-irradiated FM steels are quite different from those of steels irradiated with fission neutrons at doses above about 10 dpa. To better understand the irradiation-induced microstructural and chemical evolution, atom probe tomography studies were conducted on F82H, Eurofer 97 and ODS Eurofer steels irradiated to doses up to 20 dpa at temperatures up to 500°C. Topics include: 1) Radiation-induced segregation at grain boundaries of low and high angles, 2) Radiation-induced formation and evolution of nanoparticles, and 3) Spallation products and associated microstructures. In this talk, the major results will be presented.

Bio:

Yong Dai is a senior scientist at the Nuclear Materials Laboratory of the Paul Scherer Institute (PSI) in Switzerland, and an associate editor of Elsevier’s Journal of Nuclear Materials. In 1995 he received his Ph.D. at the Swiss Federal Institute of Technology (EPFL) in Lausanne. He has been with PSI since 1995 and led a team working on materials related to spallation neutron sources. He is responsible for irradiation experiments on targets at the Swiss Spallation Neutron Source (SINQ), in which about 20 international institutes and universities have participated. His research work focuses on the effects of radiation damage, helium, hydrogen and liquid metals on various structural materials and pure metals.