High-temperature and low-stress creep anisotropy of single-crystal superalloys

Dislocation network with pair-coupling structure in {111} γ/γ′ interface of Ni-based single crystal superalloy

“…The effect of the testing condition on the formation of {111} interface dislocation network is studied as summarized in Table 2 ; these experimental results indicate that the network formation arises as a consequence of both the applied stress and the creep temperature. Rafting of γ′ structure and its following degradation are prevalent for Ni based single-crystal superalloys during high temperature/ low stress creep 5 14 15 16 . Under the applied stress, the dislocations gliding from γ channel start to cut into the rafted γ′ during the degrading of rafting structure; at this point, they couple with each other due to the removal of APB in γ′.…”

“…The γ-γ′ interface of {001} type is prevalent in the γ′ raft structure which is completed during steady-state creep at high temperature. However, the {111}-type distorted interface has been found frequently when the γ′ raft structure continues to be broken by dislocations cutting via {111} plane of this interface; this phenomenon is prevalent in superalloys crept at high temperature/low stress 5 14 15 16 . In addition, as the misfit becomes more negative, the stress field in the interface increases 4 ; this leads to the dissolution of the unstable γ′ phase near the interface 17 , which contributes to the formation of {111} interface.…”

How Nanoscale Dislocation Reactions Govern Low- Temperature and High-Stress Creep of Ni-Base Single Crystal Superalloys

“…An electrolyte consisting of 70 vol.-% methanol, 20 vol.-% glycerin, and 10 vol.-% perchloric acid yielded good thinning results at 2 • C, a voltage close to 14 V, and a flow rate of 16. All details describing TEM specimen preparation and the standard TEM procedures used in the present work have been described elsewhere [10,11,[16][17][18][19]. The microstructure of the material prior to creep is shown in Figures 2 (SEM) and 3 (TEM) of [10].…”

Influence of misfit stresses on dislocation glide in single crystal superalloys: A three-dimensional discrete dislocation dynamics study

“…It was reported in the literature that the creep behavior is closely related to conservative and non-conservative dislocation motion, as well as dislocation self-interaction and dislocation interaction with coherent precipitates, see for example Leverant andKear (1970), Feller-Kniepmeier andLink (1989), Pollock and Argon (1992), Sass et al (1996), Reed et al (1999), Rae and Reed (2007), Agudo Jácome et al (2013). In the heat treated state, single crystal superalloys contain low dislocation densities in the γ matrix and γ′ precipitates are essentially dislocation-free.…”