ANISOTROPIC CREEP-BEHAVIOR OF A NICKEL-BASED SUPERALLOY COMPARED WITHSINGLE-PHASE NICKEL SOLID-SOLUTION AND GAMMA' PHASE SINGLE-CRYSTALS

The creep behavior of three different single crystal alloys with vario us orientations at a temperature of 1123 K was investigated. The aniso tropic behavior of the nickel-based superalloy CMSX-4 has been reporte d recently [1-3]. These observations are compared with the anisotropic creep behavior of the isolated phases which build up the two phase su peralloy. The matrix material is given by a nickel solid solution sing le crystal, whereas the gamma' phase is represented by the alloy Ni75A l22Ti1Ta2. A detailed analysis of the deformed samples with respect to phase nucleation and dislocation configurations has been carried out. Single phase specimens show strong dislocation interactions during pr imary creep, resulting in a more homogeneous distribution of activated glide planes and an increasing amount of non-screw dislocations in th e secondary creep stage. (C) 1997 Elsevier Science S.A.