Impact of Re-clustering on resistances to dislocation slip mediated plastic deformations in γ matrix phases

Generalized planar fault energy curves (i.e., Gamma - surfaces) along the lowest energy path can provide a great deal of information on the nucleation and movement of dislocations. Using the first-principles calculation, the influence of Re-clustering on Gamma - surfaces and ideal shear strengths sigma(max) in the [11 (2) over bar](111) slip direction in the gamma phase of Ni-based single crystal (SC) superalloys is investigated. An isolated substitution of Re for Ni atoms (i.e., Re-Ni), which can reduce intrinsic stacking fault energy gamma(isf), raise unstable stacking fault energy gamma(usf) and enhance sigma(max), is demonstrated to be beneficial to reinforce the resistance to dislocation slip mediated plastic deformations. With the increase of Re-additions, Re atoms tend to separate apart from each other, but a clustering phenomena is likely to occurs in gamma matrixes at some special stages of creep of Ni-based SC superalloys. A careful analysis for the Gamma - surface and sigma(max) in gamma-Ni(Re) phases shows the geometrical configuration and spatial arrangement of Re-Ni defects has a significant impact on the nucleation and movement of a(0)/6[11 (2) over bar](111) Shockley partials, and the distance between Re-Ni defects is dominant compared with their position orientation. sigma(max) is revealed to be very sensitive to the clustering degree of Re atoms, while Gamma - surfacemainly depend on the size of Re-clusters. As the interaction between Re-Ni defects being characterized by a correlation energy function Delta E-i, it is found that a strong repulsion caused by Re-clustering is unfavorable for the strengthening of Ni-based SC superalloys, although the resistance to dislocation slip mediated plastic deformations in gamma-Ni(Re) phases can benefit from more Re-additions.