Tensile properties and microstructure of helium implanted EUROFER ODS

To study the effect of helium (He) on tensile properties and microstructure of oxide dispersion strengthened EUROFER-ODS steel, flat tensile specimens were homogeneously implanted with 30 MeV alpha-particles at the NRC KI cyclotron up to 1000 appm He at 573 K and 773 K. High-resolution and energy-filtered transmission electron microscopy showed that partly coherent Y2O3 particles are strong trapping centers for diffusing He atoms (at least up to 773 K) in reduced activation ferritic/martensitic 9Cr-1WMnVTa-0.3Y(2)O(3) steel. After 573 K and 773 K implantation the He bubbles or He filled voids have average diameters of 1.9 and 4.2 nm with concentrations about 8 x 10(22) and 7 x 10(22) m(-3), respectively. Tensile testing after 573 K implantation revealed a uniform elongation of more than 10%, despite an irradiation induced hardening of about 250 MPa. The role that nanoscaled Y2O3 particles play in He distribution, tensile properties, and on the mitigation of He embrittlement are discussed. (C) 2013 Karlsruhe Institute of Technology (KIT). Published by Elsevier B.V. All rights reserved.