Anisotropic creep properties of the nickel-base superalloy CMSX-4

Single crystals of the superalloy CMSX-4 were tested in tensile creep in order to investigate the influence of orientation on the creep behaviour at temperatures of 1123 and 1253 K. The creep response of the CMSX-4 crystals was found to be highly anisotropic at the lower temperature of 1123 K. In particular, the primary creep behaviour of near [001] and [011] oriented crystals is highly sensitive to even small misorientations. Secondary creep strength deteriorates considerably in the order [001]-[011]-[111]. At 1253 K the creep anisotropy is clearly reduced, the creep strength of the [111] orientation, however, remains poor. The evolution of the microstructure during creep was studied as a function of strain and orientation and the relationship between deformation mechanisms and creep properties is discussed.