Correlation of microstructural and mechanical properties of neutron irradiated EUROFER97 steel

The reduced activation ferritic-martensitic (RAFM) steel EUROFER97 was neutron irradiated to an average dose of 16.3 dpa at temperatures from 250 degrees C to 415 degrees C. Radiation-induced defects such as dislocation loops and voids were characterized by transmission electron microscopy (TEM). The quantitative analysis of the microstructural results includes the determination of the Burgers vector, the size, number density of defects and the calculation of the relaxation volume of the loops or void swelling. The dislocation loops with b1/2 < 111 > Burgers vector were found in the material irradiated at 250 degrees C and 300 degrees C, while at higher temperatures a preferential formation of b<100> loops was observed. The voids were found only in material irradiated at 350 degrees C and 400 degrees C. The maximum relaxation volume of the loops and void swelling was measured for 350 degrees C. The dispersed barrier hardening (DBH) model was found to accurately predict the yield strength in the material irradiated at the temperatures >= 350 degrees C. The difference between experiment and DBH model at lower temperatures is due to the formation of nanovoids or interstitial loops with a size of <2 nm that are not recognizable in the TEM. (c) 2020 Karlsruhe Institute of Technology. Published by Elsevier B.V. All rights reserved.