Abstract:The anomalous flow behavior of γ′-Ni₃Al phases at high temperature is closely related to the cross-slip of 1/2á110？{111} super-partial dislocations. Generalized stacking fault energy curves (i.e., Γ-surfaces) along the lowest energy path can provide a great deal of information on the nucleation and movement of dislocations. With the first-principles calculation, the interplay between Re and W, Mo, Ta, Ti doped at preferential sites and their synergetic influence on Γ-surfaces and ideal shear strength (τ_max) in γ′-Ni₃Al phases are investigated. Similar to single Re-addition, the Suzuki segregation of W at stacking faults is demonstrated to enable to impede the movement of 1/6á112？{111} Shockley partial dislocations and promote the cross-slip of 1/2á110？{111} super-partial dislocations. With the replacement of a part of Re by W, a decreased indicates that the anomalous flow behavior of γ′ phases at high temperature is not as excellent as the double Re-addition, but an increased τ_max means that the creep rupture strength of Ni-based single crystal superalloys can be benefited from this replacement to some extent, especially in the co-segregation of Re and W at Al-Al sites. As the interaction between X1_Al and X2_Al point defects is characterized by an correlation energy function , it is found that both strong attraction and strong repulsion are unfavarable for the improvement of yield strengths of γ′ phase.

Key words: Ni-based single crystal superalloy; γ′-Ni₃Al; generalized stacking fault energy; ideal shear strength; dislocation; cross-slip