Interfacial microstructure evolution and mechanical properties of B4C-based composite joints bonded with Ti foil

The interfacial microstructure and mechanical properties of B4C-SiC-TiB2 composite joints diffusion bonded with Ti foil interlayer were investigated. The joints were diffusion bonded in the temperature range of 800-1200 °C with 50 MPa by spark plasma sintering. The results revealed that robust joint could be successfully obtained due to the interface reaction. B4C reacted with Ti to form nanocrystalline TiB2 and TiC at the interface at 800-1000 °C. Both the reactions between SiC and Ti and between TiB2 and Ti were not observed during joining. A full ceramic joint consisted of micron- and submicron-sized TiB2 and TiC, accompanied with the formation of micro-crack, was achieved for the joint bonded at 1200 °C. Joint strength was evaluated and the maximum shear strength (145 ± 14.1 MPa) was obtained for the joint bonded at 900 °C. Vickers hardness of interlayer increased with increasing the joining temperature.