Diffusion bonding of TiAl intermetallic and Ti₃AlC₂ ceramic: Interfacial microstructure and joining properties

TiAl intermetallics and Ti₃AlC₂ ceramics were jointed through diffusion bonding using Ti/Ni interlayer. The effect of bonding temperature and holding time on interfacial microstructure and mechanical properties of the bonded joints were investigated. The typical interfacial microstructure of the joint from TiAl to Ti₃AlC₂ side could be divided into τ₃-Al₃NiTi₂, α₂-Ti₃Al, α-Ti+δ-Ti₂Ni, δ-Ti₂Ni, β₂-TiNi, η-TiNi₃, γ-(Ni)_ss, γ'-Ni₃(Al, Ti), γ'-Ni₃(Al, Ti)+Ti₃AlC₂, respectively. The value of the microhardness in the reactive zones increased due to the formation of intermetallcs. Lower or higher bonding temperature and longer or shorter holding time both resulted in low strength owing to the insufficient diffusion of atoms or excessive formation of intermetallics. A high bonding strength can be obtained when bonding at 920°C for 60min. Fracture occurred through the intermetallic layer adjacent to the Ti₃AlC₂ substrate during shear test, showing brittle intergranular and transgranular characteristic.