A new partial transient liquid-phase bonding process with powder-mixture interlayer for bonding Cf/SiC composite and Ti–6Al–4V alloy

●A new PTLP bonding process with a powder-mixture interlayer is proposed.●The powder-mixture interlayer is mixed by TiNiNb alloy powders and Nb powders.●Cf/SiC composite was successfully joined to TC4 alloy by the new bonding method.●The microstructure and formation mechanism of the joints were investigated.

A new partial transient liquid-phase (PTLP) process was carried out for bonding Cf/SiC composite and Ti–6Al–4V alloy at 980 °C for 30 min. Mixed powders of Ti54.8Ni34.4Nb10.8 (at%) eutectic and Nb metal were used as an interlayer, which will be a liquid phase coexisting with solid particles at the bonding temperature. Compared with typical multi-layer interlayer in PTLP bonding, the powder-mixture interlayer is more flexible in the design of joint structure and bonding surface, which needs less bonding time and benefits to release the thermal stress in the joint. The microstructure and formation mechanism of the bonded joints have been preliminarily investigated. The results showed that a reaction layer consisting of TiC and NbC formed at the Cf/SiC composite interface. A diffusion layer grew on the interface of TC4 alloy. In the connection layer, the residual Nb particles were wrapped by β-(Ti,Nb) phases and distributed in Ti2Ni matrix together with the other massive β-(Ti,Nb) phases. Due to good plasticity and dispersive distribution, the residual Nb particles would help to release the thermal stress in the joint.