Orientation selected micro-pillar compression behavior of heavy-ions irradiated RAFMs

Abstract

The present study aimed to investigate the mechanical property of heavy ions irradiated Reduced Activation Ferrite/Martensitic (RAFM) steels. The CLF-1 steel was irradiated by 33.5 MeV Fe ions at room temperature, resulting a peak displacement damage of 20 displacements per atom (dpa). Experimental analysis was conducted using Electron Backscatter Diffraction (EBSD) mapping-assisted Focused Ion Beam (FIB) technique to prepare micro-pillars oriented along crystal directions <0 0 1>. Subsequently, these fabricated micro-pillars underwent compression tests utilizing a flat indenter within the Nano-indentation setup. Engineering Stress-strain curves were generated for specimens both un-irradiated and irradiated. The yield strength of the un-irradiated and irradiated specimens in the <0 0 1> directions was determined by using the engineering stress-strain curves. In addition, the critical resolved shear stress (CRSS) of the un-irradiated and irradiated specimens was calculated. Microstructural analysis revealed that the formation of dense and fine dislocation loops were appeared in the material after irradiation. By combining the results of microstructure analysis with the dispersion barrier hardening model, the changes in CRSS caused by irradiation were calculated. Furthermore, the number of dislocation lines participating in deformation at a strain of 20 % was quantified, with the irradiated specimen exhibiting an increase of 33 % in comparison to the un-irradiated specimen.