Interfacial reaction mechanisms of heat-resistant diamond/Cu joint synergistically achieved by active modified layer and NiTi particles assisted isothermal solidification

A novel transient liquid phase bonding (TLP) method for obtaining high-temperature resistant diamond/Cu joint was designed. The joint was achieved through the isothermal solidification of Au–Si interlayer assisted by the diamond active modified layer and NiTi particles. The interfacial reaction mechanisms in the TLP process were systematically investigated in this study. The results shown that Ti5Si3C, CuTiSi and NiTiSi precipitated from the seam. Due to the precipitation of Si and the interdiffusion of Au–Cu, a ductile Au–Cu solid solution ((Au, Cu)ss) matrix formed. The shear strength of the diamond/Cu joint was notably affected by the holding time. The maximum room-temperature shear strength of 108 MPa was achieved when the joints were held at 600 °C for 60 min, and the high-temperature strength was still up to 22 MPa at 600 °C. The high strength of the joints was achieved because of (i) the elimination of the Cu(Au)–Si brittle phases, (ii) the NiTiSi whiskers pulling-out mechanism, and (iii) the moderate distribution of compounds at the diamond/seam interface.