Microstructure and mechanical properties of diffusion bonded single crystal to polycrystalline Ni-based superalloys joint

► Single crystal DD3 and polycrystalline GH4169 Ni-based superalloy were diffusion bonded. ► The morphology of γ′ phase changed from cuboidal to columnar shape. ► The size of the γ′ phase in the diffusion zone was less than 1 μm. ► The shear strength reached 433 MPa accompanied by a dimple fracture.