Abstract: The diffusion bonding test of FGH91 powder metallurgy (PM) superalloy and K418B castedblade was carried out by hot isostatic pressing (HIP). The elemental diffusion at the interface of FGH91-K418B dual alloys and the microstructure and mechanical properties of the joint were investigated. The results show that, under the condition that the bonding interface is clean enough and the HIP process is 1190 ℃+170 MPa, the good metallurgical bonding of FGH91 and K418B can be achieved. In addition, the diffusion bonding joint is compact and complete, and no inclusions and continuous second-phase precipitates are found. The width of the diffusion zone is in the range of 80~120 μm. The FGH91-K418B dual alloys have the good consistency of tensile properties, stress rupture properties, and microstructure, and the fracture does not occur at the interface joint.