Aspects of primary creep of a single crystal nickel-base superalloy

Abstract

Primary tensile creep curve has been measured for a single crystal nickel-base superalloy and microstructure for specimens parallel to (100) crystal plane at different creep times have been observed by means of transmission electron microscopy (TEM). The results show that the 1/2[110] dislocation is activated on the octahedral and cube slip systems in the gamma matrix channels and multiplied by dislocation reactions. The dislocation motion must overcome greater resistance on the (100) and (010) crystal planes in the gamma matrix channels which are subjected to compression stress. Therefore, the bulk dislocations move in a form of cross-slip and shorter distance. The dislocation loop in one matrix channel moves into the other matrix channels subjected to compression stress by means of cross-slip that is similar to Frank-Read (F-R) dislocation configuration due to the pinning on both sides. After the gamma' is rafted, the climbing of dislocations is the principal mechanism of the creep deformation. (C) 1999 Elsevier Science S.A. All rights reserved.