Microstructure and fracture properties of reaction-assisted diffusion bonding of TiAl intermetallic with Al/Ni multilayer foils

Reaction-assisted diffusion bonding of TiAl intermetallic was performed using Al/Ni multilayer foils as interlayers. The typical microstructure and the joining mechanism were investigated. The Ni3(AlTi), Ni2AlTi, NiAl2Ti and (Ni,Al,Ti) reaction phases were observed at the interface between the Al/Ni multilayer foils and the TiAl substrate. The reaction products in the multilayer foils were mostly composed of AlNi3. The joining between the multilayer and the substrate relied on the formation of Ti–Al–Ni compounds. The joining temperature played a strong influence on the microstructure of the joint. The fracture mainly took place between the NiAl2Ti layer and the substrate and the fracture presented a typical brittle characteristic.