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

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 left angle 110 right angle dislocation is activated on the octahedral and cube slip systems in the γ matrix channels and multiplied by dislocation reactions. The dislocation motion must overcome greater resistance on the (100) and (010) crystal planes in the γ 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 γ' is rafted, the climbing of dislocations is the principal mechanism of the creep deformation. (orig.)