The influence of interface structure on the microstructure and properties of Cu/graphite joint prepared by vacuum diffusion bonding

Abstract

The hybrid structure of copper and graphite has important applications in plasma-oriented components and automobile commutators. In view of the poor wettability of copper to graphite and the large residual stress of the joint, the Cu and TiH2 mixed powder was used as the interlayer and the corrugated interface structure was designed for Cu/graphite vacuum diffusion bonding in this paper. The metallurgical reaction between active element Ti and the matrix on both sides was investigated. It showed that the Ti reacted with C atoms on surface layer of the graphite to form a TiC reaction layer with thickness of 0.5–1 μm, while Ti and Cu formed solid solution and Cu–Ti intermetallic compounds. The Cu/graphite joint consisted of graphite/TiC layer/Ti–Cu intermetallic compound + Cu-based solid solution/Cu. The relief of residual stress benefit by the corrugated interface structure were revealed. The shear strength of the joints with the long wavelengths structure reached 22.9 MPa. The corrugated interface structure can obviously change the distribution of residual stress in the joint, thus effectively improving the bonding strength of the Cu/graphite joint.