Interfacial microstructure and properties of Ti(C, N)/Ni bonded by transient liquid-phase diffusion

Effects of the main process parameters(temperature and time) on microstructure and properties of Ti(C, N)/Ni interface bonded by (Cu+Nb) interlayer in a vacuum diffusion bonding device were investigated. The interfacial microstructures consisted initially of Ni3Nb metallic compound and eutectic of Ni3Nb+CuNiSS, and finally transformed to (Ti, Nb) (C, N)+Ni3Nb near Ti (C, N) and NiCuSS+Ni3Nb near Ni when diffusion bonding temperature was 1 523–1 573 K. It was clear that Cu was a constituent in the transient liquid phase (TLP) into which Ni was dissolved by forming Cu-Ni transition liquid. Nb was dissolved in Cu-Ni transition liquid rapidly. Ti (C, N) conld be wetted by resultant Ni-Nb-Cu transient liquid phase which was followed by a little (Ti, Nb) (C, N) solid solution formed at interface. This increased the interface combining capability. Ultimately the interface shear strength was able to reach 140 MPa. The theoretle analysis and experimental results show that the growth of interfacial reaction layer Ni3Nb accords with parabola law, and the activation energy of diffusion reaction is 115.0±0.5 kJ/mol, while the diffusion reaction speed constant is 12.53 mm/s1/2.