Image force on a dislocation in a Ni-based superalloy due to the γ—γ′ interface

Abstract

The image force due to the γ—γ′ interfaces on dislocations situated in the γ channels or in the γ′ precipitates in Ni-based superalloys is investigated on the basis of the anisotropic theory of elasticity. The results are affected by the choice of the elastic constants available in the literature but, in most cases, the values of the image forces are comparable with those of the other forces acting on the dislocations. At room temperature, the sense of the image forces does not depend on the choice of the elastic constants; the dislocations in γ are always attracted to the interfaces and those in γ′ are always repelled from them. At 1050°C, however, opposite conclusions may be reached depending on the constants used. These different effects are discussed by comparison with the configurations observed by in situ transmission electron microscopy.