Interfacial structures evolution at hetero interfaces in SiCf/SiC | Nb | SiCf/SiC sandwich cladding structure

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 b-SiC | NbC | Nb5Si4C | a-Nb5Si3 | b-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 degrees C. Lastly, the formation mechanisms of interfacial structures are revealed based on thermodynamics and kinetics, meanwhile the diffusion coefficients k at 1500 degrees C and activation energy are calculated to be 2.81 x 10-14 m2/s and 270 kJ/mol, respectively. This work provides a practical strategy for developing hybrid composites of metal/ceramic matrix composites.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).