TEM Analysis of Diffusion-Bonded Silicon Carbide Ceramics Joined Using Metallic Interlayers

Silicon Carbide (SiC) is a promising material for thermostructural applications due to its excellent high-temperature mechanical properties, oxidation resistance, and thermal stability. However, joining and integration technologies are indispensable for this material in order to fabricate large size and complex shape components with desired functionalities. Although diffusion bonding techniques using metallic interlayers have been commonly utilized to bond various SiC ceramics, detailed microstructural observation by Transmission Electron Microscopy (TEM) of the bonded area has not been carried out due to difficulty in preparing TEM samples. In this study, we tried to prepare TEM samples from joints of diffusion bonded SiC ceramics by Focused Ion Beam (FIB) system and carefully investigated the interfacial microstructure by TEM analysis. The samples used in this study were SiC fiber bonded ceramics (SA-Tyrannohex: SA-THX) diffusion bonded with metallic interlayers such as Ti, TiMo, Mo-B and TiCu. In this presentation, we report the microstructure of diffusion bonded SA-THX mainly with TiCu interlayers obtained by TEM observations, and the influence of metallic interlayers on the joint microstructure and microhardness will be discussed.