High temperature radiation responses of amorphous SiOC/crystalline Fe nanocomposite

The radiation tolerance of amorphous silicon oxycarbide (SiOC) and crystalline Fe nanocomposites were examined by ion irradiation and transmission electron microscopy characterization. A comparison was made between a pure Fe film and SiOC/Fe multilayers. The composites were subjected to 120 keV He⁺ ions to average damage levels from approximately 0.5 to 10.7 displacements per atom (dpa) at 600 °C. Compared to pure Fe films, the swelling resistance in the Fe layers of thick SiOC/Fe (80/60 nm) multilayer films is improved by 2.2 times and the averaged void size is reduced to half. In some instances, a crystalline Fe_xSi_yO_z reaction layer formed between the Fe and SiOC components of the composite, and the interface between Fe and Fe_xSi_yO_z was observed to be incoherent. Void denuded zones were observed in the Fe layer close to the SiOC/Fe and Fe/Fe_xSi_yO_z interfaces. For thin SiOC/Fe (14/14 nm) multilayers, layer breakdown was observed and the extent of the layer breakdown became more significant with increasing dpa values. However, there were no voids in the Fe component of the thin SiOC/Fe nanocomposites. These results suggest that the SiOC/Fe and Fe/Fe_xSi_yO_z interfaces act as efficient defect sinks which promote point defect recombination and suppress void swelling. - Graphical abstract: Typical cross-sectional TEM images from (a) thick Fe/SiOC multilayers, and (b) a pure Fe film after 600 °C irradiation (dose of 8 × 10²¹ ion/m²). Statistical analysis of (c) void size and (d) void swelling in pure Fe films and Fe layers from thick Fe/SiOC multilayer composites as function of damage levels. Compared to pure Fe films, the swelling resistance in the Fe layers in thick Fe/SiOC multilayer composite is improved by 2.2 times and the averaged void size is reduced to half. Display Omitted - Highlights: • Radiation tolerance of amorphous SiOC and α-Fe nanocomposites at 600 °C are examined. • Compared to pure Fe films, thick Fe/SiOC multilayer composite exhibits smaller void size and more swelling resistance. • No voids are observed in the Fe component of the thin Fe/SiOC composites. • These results suggest that the Fe/SiOC interface promotes point defect recombination and suppresses void swelling.