| Summary: | The appropriate hetero interfacial structure between metal and ceramics is a challenging topic in materials science. In this paper, a sandwich hybrid cladding structure made of SiCf/SiC composite and refractory metal niobium (Nb) is designed for application in a lead-cooled fast reactor. A diffusion reactive interfacial layer composed of β-SiC | NbC | Nb5Si4C | α-Nb5Si3 | β-Nb2C | Nb between SiCf/SiC composite and Nb is experimentally validated after heat treatment in a simulating reactor environment. Moreover, Kirkendall voids are found at the interface between Nb5Si4C and Nb5Si3 sublayers when the annealing temperature is higher than 1500 °C. Lastly, the formation mechanisms of interfacial structures are revealed based on thermodynamics and kinetics, meanwhile the diffusion coefficients k at 1500 °C and activation energy are calculated to be 2.81 × 10−14 m2/s and 270 kJ/mol, respectively. This work provides a practical strategy for developing hybrid composites of metal/ceramic matrix composites.
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