Study of the γ/γ' interfacial structure during the primary creep stage of high-temperature and low-stress creep in a Re doping nickel-based single crystal superalloy

For deeply understanding the creep behavior and the strengthening mechanism of Re doping nickel-based single crystal superalloys during the primary creep stage of high-temperature and low-stress creep, electron microscopy and energy dispersive X-ray spectroscopy are used to study the γ/γ' interfacial structure from mesoscopic to atomic scale in the DD6 single crystal superalloy crept for 15 min under 1100℃/140 MPa. The dislocation configuration, the core structure of interfacial dislocations and the elemental distribution around the interfacial dislocations have been carefully investigated. It is shown that the dislocation density is relatively low during the primary creep, and the dislocation networks are only locally formed. Thus fewer interfacial protrusions are formed compared to the stable creep stage (12 h), and more step-like protrusions (corresponding to the a/2<101>60° mixed dislocations) have been observed than the V-shaped protrusions (corresponding to the a/2<110> edge dislocations which are formed by dislocation reaction). The special configuration of the step-like protrusions during the primary creep stage are formed by the dislocation motion along the γ/γ' interface and co-segregation of Re with other alloying elements could help to confirm the interaction of Re segregation with interfacial dislocations. © 2016, Science Press. All right reserved.