Ni-based single crystal superalloy has excellent high temperature properties, which is the main materials for aero-engine turbine blade. In order to improve the yield strength of single crystal blades, the reliable bonding technology has become an increasingly indispensable key technology in the process of producing single crystal blades. However, there is inevitably an orientation deviation in the bonded single crystal component, owing to its shape complexity and randomness during assembly practice of bonding single crystal components. The CMSX-4 single crystal superalloy with the orientation combination of 0 degrees+0 degrees, 0 degrees+45 degrees and 0 degrees+90 degrees were brazed by Ni-based filler alloy at 1210 degrees C for 30 min and carried out ageing heat treatment. The effect of base material orientation combination on the microstructure was analyzed by SEM, EBSD and EPMA. The mechanical properties of joints after bonding and ageing treatment were tested. The result indicates that the microstructures and phase compositions of three orientation combination joints were similar in the filler alloy zone, consisting of gamma-Ni, gamma', gamma+gamma' eutectic, M3B2 type boride, CrB, nickel-silicon compound and gamma-Ni+Ni3B+CrB ternary eutectic phase. The melting point depressant B in the filler alloy is not diffused significantly to the base material, and no brittle compound phase is precipitated in the diffusion affected zone of the joint. After ageing treatment, elements diffusion is uniform and brittle precipitates are reduced, and the continuous grain boundary can be observed at the center of the joint when the base material on both sides of the joint has orientation deviation. The testing results of mechanical properties show that the base material orientation deviation has no distinctly effect on the room and high temperature tensile properties of the joint. However, the tensile strengths of the joint at room and high temperature both reduce with orientation deviation after ageing treatment, but the degree of orientation deviation has no obvious influence on the tensile strength of the joint. The fracture of the three joints occurs in the filler alloy zone.
