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 beha viour at temperatures of 1123 and 1253 K. The creep response of the CM SX-4 crystals was found to be highly anisotropic at the lower temperat ure of 1123 K. In particular, the primary creep behaviour of near [001 ] and [011] oriented crystals is highly sensitive to even small misori entations. Secondary creep strength deteriorates considerably in the o rder [001]-[011]-[111]. At 1253 K the creep anisotropy is clearly redu ced, the creep strength of the [111] orientation, however, remains poo r. The evolution of the microstructure during creep was studied as a f unction of strain and orientation and the relationship between deforma tion mechanisms and creep properties is discussed.