Formation and role of dislocation networks during high temperature creep of a single crystal nickel-base superalloy

An investigation has been made into the formation and role of dislocation networks during high temperature creep in a single crystal nickel-base (Ni-Al-Mo-Ta) superalloy. The results show that the three-dimension networks in the matrix channels are formed by the reaction of dislocations during primary creep. It is found that these three-dimension networks formed at the gamma'/gamma interfaces play an important role in accommodation of the strain hardening and the recovery softening during steady state creep. However, in the tertiary creep stage, the main deformation feature of the alloy is the shearing of the gamma' rafts by the moving dislocations in matrix from the gamma'/gamma phase interfaces where the dislocation networks are damaged. (C) 2000 Elsevier Science S.A. All rights reserved.