Microstructures and bonding strength of synthetic diamond brazed by near-eutectic Ag–Cu–in–Ti filler alloy

Synthetic diamond is often bonded to metals or itself to fulfil the functional requirements for the applications in machine tools or the fabrication of thermal management materials. The knowledge on the relationship between interfacial microstructure and bonding strength of the synthetic diamond is therefore of significant scientific and technological implications. In this work, the epitaxial growth of titanium carbides formed on synthetic diamond grits brazed using a near-eutectic Ag–Cu–In–Ti active filler alloy was systematically investigated. An ultra-thin TiC layer was identified on the synthetic girts brazed at 680 °C and the epitaxial growth of Ti3InC carbides together with Ag3In and Cu2InTi intermetallics (IMCs) were subsequently examined at the brazing temperatures of up to 880 °C. The solidification microstructures of the Ag–Cu–In–Ti filler alloy in the brazed diamond joints were discussed based on composition analysis and phase diagram information. The growth morphologies of the interfacial products were exemplified by taking the bonding strength, fracture behaviours, and integrity of the brazed synthetic diamond into account. The results obtained would be of great value for developing diamond related devices and materials.