Negative Creep of Single Crystals of Nickel–Based Superalloys

Negative creep of single crystals of two nickel-based superalloys has been studied. This phenomenon was observed for both alloys at temperatures of 980–1000°C and low or zero loading stresses. It is assumed that the main reason for negative creep is the formation of short-range order of atoms in the highly alloyed lattice of the matrix γ-phase. Additional factors influencing the magnitude and anisotropy of negative creep deformation can be the relaxation of residual stresses: at the microscopic level - misfit stresses between the γ-matrix and the strengthening γ′-precipitates, and at the mesoscopic level - dendritic stresses between the dendritic axes and interdendritic regions.