Quantitative study of the plastic slip deformation and formation of internal stresses in Ni-base superalloys

When nickel-base superalloys deform by creep in a high temperature atmosphere, cuboidal shaped strengthening precipitates of γ′ phase usually grow in the direction perpendicular to the loading axis. The mechanism of this “rafting” phenomenon is studied in terms of the movement, reactions and accumulation of dislocations in γ channels. Characteristics of the dislocations which accumulate on the γ-γ′ interfaces are discussed and the internal stresses generated by the accumulation of the glide dislocations are analyzed in terms of the geometrically necessary dislocations which accompany the gradient of the plastic shear strain.