Interfacial Microstructure and Reaction Phases of Solid State Bonded at SiC/V Joints

Abstract

SiC was bonded to SiC using V foil at temperatures ranging from 1473 K to 1673 K for 1.8 to 64.8 × 103 s and 30 MPa in vacuum. Interfacial reactions and microstructures were investigated using electron probe microanalyser and X-ray diffractometer. SiC begins to react with V at temperatures above 1473 K. Granular V2C phase was formed at the V side of the reaction zone, while a layer of V3Si phase was formed at the interface between V2C and SiC after bonding at 1573 K for 1.8 and 7.2 × 103 s. The same reaction structure can be observed at 1473 and 1673 K for 1.8 × 103 s. Hexagonal V5Si3Cx (X < 1) phase was formed at the interface between V3Si and SiC after bonding at 1573 K for 14.4 and 21.6 × 103 s, and the interface structure of the joint became SiC/V5Si3Cx/V3Si/V2C + V/V. This microstructure represents a complete diffusion path which is correlated with the corresponding Si-V-C phase diagram. At the longer bonding time of 64.8 × 103 s, V was completely consumed, and the joint showed the layer structure of SiC/V5Si3Cx/V3Si/V2C/V3Si/V5Si3Cx/SiC.