Abstract: Microstructural evolution of transient liquid phase(TLP) diffusion bonding joint of IC10 single crystal superalloy was investigated with scanning electron microscopy(SEM) and energy-dispersive spectrum(EDS).The results show that the joint contained bonding zone and base material zone.The bonding zone consisted of isothermal solidification zone and rapid solidification zone.Rapid solidification zone could be eliminated by increasing welding time.The size of γ' phase in the base material reached 0.9 μm when the welding time increased from 2 h to 8 h.The mechanical properties of the joints can be effectively improved by restraining formation of grain boundary in TLP diffusion bonding joint and postweld solution treatment.The average tensile strength of the joints was 507 MPa at 1 000℃.The creep rupture life of the joints reached 120 h under the condition of 144 MPa stress at 1 000℃.