Dual-Beam irradiation of spark plasma sintered ODS Fe-14Cr alloys

ODS Fe14Cr alloys are considered as candidates for the replacement of austenitic steels in nuclear applications such as cladding tubes for future sodium fast rectors. This requires a background on the fabrication route, properties and irradiation behavior. Samples with yttria contents of 0.6wt% were produced by mechanical alloying and subsequent consolidation via spark plasma sintering (SPS). The grain size and particle type and size were characterized by means of electron backscatter diffraction (EBSD) and atom probe tomography (APT), respectively. The microstructural homogeneity was evaluated by a combination of EBSD and scanning nanoindentation (SNI). SNI mappings are displayed in Fig. 1. A pronounced inhomogeneity of the hardness value at the µm size scale is observed. The homogeneity is clearly influenced by the milling parameters. The relationship between hardness, grain size and spatial distribution of nanoparticles is considered.
The compacted samples were irradiated with iron ions and with iron and helium ions (dual-beam irradiation) in order to investigate the influence of yttria particles on the helium bubble formation. The irradiated and unirradiated materials are characterized with respect to indentation hardness and microstructure.