Exploring The Microstructural Evolution of Interfacial Diffusion Layers in SiC/SiC/Ta Hybrid Cladding Tubes under Ion Irradiation: An In-Situ TEM Study

Hybrid cladding tubes consisting of Ceramics Matrix Composites (CMCs) and Refractory Metal Liner are considered as one of the promising structural materials for advanced high-temperature gas/liquid metal cooled reactors. Our previous study demonstrated the feasibility of fabrication of SiC/SiC/Refractory Metal sandwich structured tubes via chemical vapor infiltration method[1]. This fabrication method (at~1000°C) does not provoke any significant interfacial reaction between SiC/SiC and Refractory metals. However, potential reactor operation conditions at higher temperature regime (&gt;1200°C) could lead to the formation of silicides/carbides layers due to the interfacial diffusion behavior[2]. Therefore, exploring the microstructural evolution of these interfacial layers under irradiation is crucial to the understanding of the radiation stability of hybrid cladding tubes. In this work, interfacial layers consisting of TaC | γ-Ta₅Si₃ | α-Ta₂C | Ta₂Si | Ta₃Si were irradiated in-situ in a transmission electron microscope using 800 keV Kr²⁺ ions at 300, 600, and 900°C. Tantalum Silicides subjected to amorphization under all temperatures, and the threshold dose for amorphization raised with increasing irradiation temperatures. Among three types of silicides, Ta₅Si₃ exhibited the best radiation resistance, whereas Ta₃Si appeared the worst. DFT calculation explained the above trend based on the defect formation energy in these Tantalum Carbides have demonstrated better radiation stability than Tantalum Silicides under all temperatures since they did not undergo any amorphization. The Rel-rod method was used to investigate the radiation damage (frank loops) in TaC. No frank loops were observed at 300°C, whereas this type of defect was observed at both 600 and 900°C. The number density of frank loops increased with accumulation of irradiation dosage. This study helps to provide an insight into the radiation stability of hybrid cladding tubes.<br/><br/>[1] C. Wei <i>et al.</i>, Preparation and interfacial layer microstructure of multilayer heterogeneous composite, Composite Part B: Engineering, 243 (2022) 110128<br/>[2] Hailong Qin <i>et al</i>, Interfacial diffusion behaviour and mechanical properties of SiC/Ta hybrid accident tolerance fuel cladding structure, Composites Part A: Applied Science and Manufacturing, 165 (2023) 107332