Interfacial microstructure of diffusion-bonded SiC and Re with Ti interlayer

Abstract

SiC plates were diffusion bonded to Re metal using a Ti interlayer by hot-pressing. For the joining, a uniaxial pressure of 25 MPa was applied from 1400 to 1600 degrees C for 2 h in an argon atmosphere. The interfacial microstructure and elemental composition of the SiC/Ti/Re joints were investigated. The Ti interlayer diffused into the SiC substrate to form carbide intermediate phases that enhance the bonding strength and also that of the layer brazed with Re metal. Multi-component phases (Ti3SiC2, Ti5Si3Cx, and TiC) were formed in the Ti interlayer with different atomic ratios. Each phase had a different coefficient of thermal expansion, causing micro-cracks and pulverization at high temperature. At 1600 degrees C, the phase ratio and thickness of the detrimental phase Ti5Si3Cx were much lower than those at other joining temperatures. For the Re/Ti interfaces, the diffusion of Ti and Si into Re gradually induced the formation of bcc-Ti precipitates, ReTi, and Re-Si alloys depending on the joining temperature. The micro-hardness was measured for the joined SiC/Ti/Re along all the interfaces. (C) 2017 Elsevier B.V. All rights reserved.