Slip and fracture behavior of δ-Ni₃Nb plates in a polycrystalline nickel-based superalloy during fatigue

The fatigue deformation behavior of δ-Ni₃Nb (D0_a intermetallic phase in nickel-based superalloy) was analyzed in detail to determine its fracture characteristics and possible slip systems. Strong arrangement-dependence (i.e. arrangement direction of plate length relative to loading direction) deformation characteristics were observed. When δ plates were arranged not paralleling to the loading direction, they exhibited certain degree of fatigue resistance. Slip traces were found in the non-parallel δ plates after some fatigue cycles. By analyzing the traces and habit plane of δ, the possible operative slip systems were confirmed to be (010)_δ[100]_δ and (010)_δ[102]_δ.