High temperature radiation responses of amorphous SiOC/crystalline Fe nanocomposite

Abstract

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 FexSiyOz reaction layer formed between the Fe and SiOC components of the composite, and the interface between Fe and FexSiyOz was observed to be incoherent. Void denuded zones were observed in the Fe layer close to the SiOC/Fe and Fe/FexSiyOz 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/FexSiyOz interfaces act as efficient defect sinks which promote point defect recombination and suppress void swelling.